The Pennsylvania State University

The Graduate School

Department of Horticulture

UTILIZING SEDUM SEEDS AS AN INSTALLATION METHOD FOR

GREEN ROOFS THROUGH SEED ENHANCEMENT TECHNIQUES

A Dissertation in

Horticulture

Kathryn Lyn McDavid

 2012 Kathryn Lyn McDavid

Submitted in Partial Fulfillment of the Requirements for the Degree of

Doctor of Philosophy

May 2012

The dissertation of Kathryn L. McDavid was reviewed and approved* by the following:

Robert Berghage Associate Professor of Horticulture Dissertation Advisor Chair of Committee

Ricky M. Bates Associate Professor of Ornamental Horticulture

E. Jay Holcomb Emeritus Professor of Floriculture

Robert D. Shannon Associate Professor of Agricultural Engineering

Richard Marini Head and Professor of the Department of Horticulture

*Signatures are on file in the Graduate School

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ABSTRACT

There are many benefits to installing green roofs including reducing storm water runoff and the associated problems with overloaded sewage systems, especially in high density urban areas. Green roofs also improve rain water and air quality and reduce the effect from urban heat islands by acting as thermal damper/evaporative coolers, which decrease heating and cooling costs and the subsequent pollution. Additionally, green roofs can extend the life of a roof and create natural habitats for birds and insects. They are also aesthetically pleasing which can improve people’s psychological state and productivity levels.

One of the primary limitations to increased green roof installations in the United States is the cost, specifically, the high costs of labor to install the plants on the roof. The majority of green roofs today are installed using cuttings and/or plugs, nursery containers, vegetative mats, or modules. Each of these installation methods has advantages and disadvantages, but each requires a significant labor investment in growing and planting the roof. Due to the lack of their success on large scale green roofs, seeds are rarely used as an installation method, especially during the summer months; however, seed installations could potentially cost far less than other installation methods.

Plant options for a green roof include various types of annuals, perennials, herbs, and succulents. Many factors influence plant selection for green roofs. Chief among them is a plant’s ability to withstand the harsh conditions found on a roof such as high temperatures and a coarse, quick-draining medium. Currently, Sedum species are the most commonly used plant for green roofs in the Eastern United States because they can tolerate and thrive in the aforementioned conditions.

Seed germination requires optimal conditions that are seldom available on a green roof.

In this dissertation, five Sedum species (Sedum acre, Sedum forsterianum, Sedum reflexum,

Sedum selskianum, and Sedum spurium) were selected to test with seed enhancement techniques and hydroseeding. Without any previously published research available describing a successful seed enhancement technique, this study sought to create a seed priming technique using a water prime and a polyethylene glycol (PEG) prime. In addition, hydromulch was used in two of the studies conducted in 2011 to determine whether it held potential as a successful seed installation method. The five species were also tested for their viability over a period of time after being stored in cool, dry storage.

The use of seed priming treatments in laboratory, greenhouse, and outdoor trials did not result in improved seed germination for most of the species. Although there was slightly higher germination in some of the primed seed species when compared to the control, the cost of the priming treatments would not be worth the small additional percentages gained in germination.

Moreover, this research demonstrated that successful seed germination on a green roof is unlikely to occur without a treatment, such as hydromulch, which holds the seeds in place near the surface of the medium.

The hydroseeded trials showed success in holding the seeds near the surface of the medium. In order to create a dense mat of Sedum species on a green roof, an ideal situation would be about 72 seedlings per square foot. Using the average germination rates from the control treatments (since they germinated as well or better than the treated seeds) of each seed species, numerical recommendations were made per square foot for hydroseeding a roof with each species.

When the five Sedum species were tested for their viability over a specified period of time, it was determined that for Sedum acre, Sedum reflexum, and Sedum spurium species, the younger seeds germinated faster and had higher germination rates in a range of temperatures.

Sedum forsterianum germination was very sensitive to increases in temperatures at any age of seed and would not, therefore, be recommended for use on a green roof. Sedum selskianum, on

v the other hand, was the only one of the five species tested whose germination appeared to be unaffected by seed age.

TABLE OF CONTENTS

LIST OF FIGURES ...... viii

LIST OF TABLES ...... x

ACKNOWLEDGEMENTS ...... xiii

Chapter 1 Literature review ...... 1

Green Roof Transitions Through History ...... 1 Green Roof Basics ...... 3 Green roof benefits ...... 3 Green roof design options ...... 6 Green roof construction...... 7 Planting considerations ...... 9 Seed Germination ...... 13 Germination Tests and Seed Maturation ...... 15 Seed Enhancement Technologies ...... 16 Seed Species ...... 18

Chapter 2 Objective of dissertation ...... 21

Chapter 3 Germination rates of multiple seed species and development of a priming method for Sedum species...... 23

Introduction ...... 23 Methods ...... 26 Germination tests ...... 26 Species selection ...... 28 Design of a successful priming method ...... 29 Experimental design, data collection, and statistical analysis ...... 30 Results and Discussion ...... 31 Development of a successful seed enhancement technique ...... 31 Conclusion ...... 37

Chapter 4 Determining Sedum moisture requirements for seed germination in a greenhouse facility ...... 38

Introduction ...... 38 Methods ...... 39 Species selection ...... 39 Design of moisture study...... 40 Experimental design, data collection, and statistical analysis ...... 41 Results and Discussion ...... 42 Conclusion ...... 52

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Chapter 5 Sedum seed installations in 2010 on the Root Cellar roof, and 2011 on the Millennium Building, hydroseeded in modules, and hydroseeded on the Root Cellar roof ...... 53

Introduction ...... 53 Methods ...... 55 Roof descriptions ...... 55 Species selection ...... 56 Design of roof studies – 2010 ...... 58 Design of roof studies – 2011 ...... 59 Experimental design, data collection, and statistical analysis ...... 61 Results and Discussion ...... 62 2010 Root Cellar roof trial results ...... 62 2011 Millennium Building trial, module trial, and Root Cellar roof trial results .... 65 Conclusion ...... 74

Chapter 6 Seed maturation over time of Sedum species ...... 76

Introduction ...... 76 Methods ...... 77 Design of maturation study ...... 77 Experimental design, data collection, and statistical analysis ...... 78 Results and Discussion ...... 78 Sedum seed maturation tested at 21.1 degree Celsius (70 degree Fahrenheit) ...... 78 Sedum seed maturation tested at 32.2 degree Celsius (90 degree Fahrenheit) ...... 85 Conclusion ...... 91

Chapter 7 Conclusion ...... 92

Seed Installation for a Green Roof ...... 92 Seed Maturation ...... 97 Future Research ...... 99

Bibliography ...... 100

Appendix A Initial Germination Results for 36 Species ...... 104

Appendix B Additional Tables From Chapter 3 ...... 115

Appendix C Additional Tables From Chapter 5 ...... 116

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LIST OF FIGURES

Figure 1-1. Urban heat island effects in a variety of locations (United States Environmental Protection Agency, 2011)...... 4

Figure 3-1. Sedum selskianum seed germination at day 21 in relation to the PEG concentration...... 34

Figure 3-2. Sedum spurium seed germination at day 21 in relation to the interaction of both priming time and the PEG concentration...... 35

Figure 3-3. Sedum spurium data for days to 50% germination in relation to the length of priming...... 36

Figure 4-1. Sedum acre seed germination rates in differing levels of moisture including mist, every other day (EOD), or every four days (E4D) watering regimes with treated (either a 4-hour or 12-hour prime in water or -0.82 MPa PEG) or untreated seed...... 43

Figure 4-2. Sedum forsterianum seed germination rates in differing levels of moisture including mist, every other day (EOD), or every four days (E4D) watering regimes with treated (either a 4-hour or 12-hour prime in water or -0.82 MPa PEG) or untreated seed...... 45

Figure 4-3. Sedum reflexum seed germination rates in differing levels of moisture including mist, every other day (EOD), or every four days (E4D) watering regimes with treated (either a 4-hour or 12-hour prime in water or -0.82 MPa PEG) or untreated seed...... 47

Figure 4-4. Sedum selskianum seed germination rates in differing levels of moisture including mist, every other day (EOD), or every four days (E4D) watering regimes with treated (either a 4-hour or 12-hour prime in water or -0.82 MPa PEG) or untreated seed...... 49

Figure 4-5. Sedum spurium seed germination rates in differing levels of moisture including mist, every other day (EOD), or every four days (E4D) watering regimes with treated (either a 4-hour or 12-hour prime in water or -0.82 MPa PEG) or untreated seed...... 51

Figure 5-1. Interaction between length of priming and priming solution for Sedum acre germination on day 21...... 68

Figure 5-2. Seed germination for Sedum reflexum based on the priming solution on day 26 (n=3)...... 69

Figure 5-3. Interaction between length of priming time and priming solution for Sedum spurium germination on day 21...... 70

Figure 5-4. Seed germination percentages in relation to the length of priming for Sedum spurium on day 32...... 71

Figure 6-1. Germination percentages for Sedum acre seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4)...... 79

Figure 6-2. Time to 50% germination for Sedum acre seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4)...... 79

Figure 6-3. Germination percentages for Sedum forsterianum seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4)...... 80

Figure 6-4. Time to 50% germination for Sedum forsterianum seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4)...... 81

Figure 6-5. Time to 50% germination for Sedum reflexum seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4)...... 82

Figure 6-6. Time to 50% germination for Sedum selskianum seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4)...... 83

Figure 6-7. Germination percentages for Sedum spurium seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4)...... 84

Figure 6-8. Time to 50% germination for Sedum spurium seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4)...... 84

Figure 6-9. Germination percentages for Sedum acre seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4)...... 85

Figure 6-10. Time to 50% germination for Sedum acre seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4)...... 86

Figure 6-11. Germination percentages for Sedum forsterianum seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4)...... 87

Figure 6-12. Germination percentages for Sedum reflexum seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4)...... 88

Figure 6-13. Time to 50% germination for Sedum reflexum seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4)...... 88

Figure 6-14. Germination percentages for Sedum selskianum seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4)...... 89

Figure 6-15. Time to 50% germination for Sedum selskianum seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4)...... 90

Figure 6-16. Germination percentages for Sedum spurium seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4)...... 91

LIST OF TABLES

Table 3-1. Scientific and common names of seed species tested...... 26

Table 3-2. List of priming concentrations and length of priming time...... 30

Table 3-3. Final germination percentages for each species in different priming times...... 32

Table 3-4. Sedum acre germination in differing concentrations of PEG and priming times...... 33

Table 3-5. Sedum reflexum germination in differing concentrations of PEG and priming times...... 33

Table 3-6. Sedum selskianum germination in differing concentrations of PEG and priming times...... 34

Table 3-7. Sedum spurium germination in differing concentrations of PEG and priming times...... 35

Table 4-1. Priming solutions for moisture study...... 41

Table 4-2. Sedum acre treated and untreated seed germination percentages in differing levels of moisture on day 14...... 42

Table 4-3. Sedum acre time to 50% germination of treated and untreated seed in differing levels of moisture...... 43

Table 4-4. Sedum forsterianum treated and untreated seed germination percentages in differing levels of moisture on day 14...... 45

Table 4-5. Sedum forsterianum time to 50% germination of treated and untreated seed in differing levels of moisture...... 46

Table 4-6. Sedum reflexum treated and untreated seed germination percentages in differing levels of moisture on day 14...... 47

Table 4-7. Sedum reflexum time to 50% germination of treated and untreated seed in differing levels of moisture...... 48

Table 4-8. Sedum selskianum treated and untreated seed germination percentages in differing levels of moisture on day 14...... 49

Table 4-9. Sedum selskianum time to 50% germination of treated and untreated seed in differing levels of moisture...... 50

Table 4-10. Sedum spurium treated and untreated seed germination percentages in differing levels of moisture on day 14...... 51

Table 4-11. Sedum spurium time to 50% germination of treated and untreated seed in differing levels of moisture...... 52

Table 5-1. Final germination of treated and untreated seed in the module study after one month (day 32)...... 71

Table 5-2. Final germination of treated and untreated seed in the Root Cellar roof hydromulch study after one month (day 34)...... 73

Table 5-3. Final germination of treated and untreated seed in the Root Cellar roof hydromulch study after two months (day 63)...... 73

Table 7-1. Calculations for the recommended number of seeds per square foot for suggested seed species...... 96

Table A-1. Cumulative seed germination results for Sedum acre and Sedum forsterianum in 10°C (50°F), 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F), 32.2°C (90°F), and 37.8°C (100°F) temperatures (30 seeds per temperature)...... 104

Table A-2. Cumulative seed germination results for Sedum reflexum and Sedum selskianum in 10°C (50°F), 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F), 32.2°C (90°F), and 37.8°C (100°F) temperatures (30 seeds per temperature)...... 105

Table A-3. Cumulative seed germination results for Sedum spurium in 10°C (50°F), 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F), 32.2°C (90°F), and 37.8°C (100°F) temperatures (30 seeds per temperature)...... 106

Table A-4. Cumulative seed germination results for Celosia plumosa, Cistanthe grandiflora, and Coreopsis grandiflora in 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F) temperatures (30 seeds per temperature)...... 107

Table A-8. Cumulative seed germination results for Prunella grandiflora, Ptilotus exaltatus, and Rudbeckia hirta in 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F) temperatures (30 seeds per temperature)...... 111

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Table A-9. Cumulative seed germination results for Rudbeckia hirta, Salvia farinacea, and Sanvitalia speciosa in 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F) temperatures (30 seeds per temperature)...... 112

Table A-10. Cumulative seed germination results for Viola wittrockiana and Zinnia marylandica in 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F) temperatures (30 seeds per temperature)...... 113

Table A-11. Cumulative seed germination results for Zinnia marylandica in 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F) temperatures (30 seeds per temperature)...... 114

Table B-1. Levels of significance of effects and interactions for germination rates for the 12-48 hour priming study. Values are P-values, ns = not significant at α = 0.05...... 115

Table B-2. Levels of significance of effects and interactions for germination rates for the 4-hour to 12-hour priming study. Values are P-values, ns = not significant at α = 0.05...... 115

Table B-3. Levels of significance of effects and interactions for time to 50% germination for the 4-hour to 12-hour priming study. Values are P-values, ns = not significant at α = 0.05...... 115

Table C-1. Levels of significance of effects and interactions for germination rates for the 2011 Millennium Building study. Values are P-values, ns = not significant at α = 0.05...... 116

Table C-2. Levels of significance of effects and interactions for germination rates for the 2011 module study on day 21. Values are P-values, ns = not significant at α = 0.05. ... 116

Table C-3. Levels of significance of effects and interactions for germination rates for the 2011 module study on day 26. Values are P-values, ns = not significant at α = 0.05. ... 116

Table C-4. Levels of significance of effects and interactions for germination rates for the 2011 module study on day 32. Values are P-values, ns = not significant at α = 0.05. ... 117

Table C-5. Levels of significance of effects and interactions for germination rates for the 2011 Root Cellar roof study on day 12. Values are P-values, ns = not significant at α = 0.05...... 117

Table C-6. Levels of significance of effects and interactions for germination rates for the 2011 Root Cellar roof study on day 34. Values are P-values, ns = not significant at α = 0.05...... 117

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ACKNOWLEDGEMENTS

I would like to express my deepest gratitude to my advisor, Dr. Robert Berghage, for creating an excellent atmosphere for research and for his guidance, advice, and patience throughout my education. I would also like to thank the rest of my committee, Dr. Ricky Bates,

Dr. Jay Holcomb, and Dr. Robert Shannon, for giving me excellent advice and assistance throughout my time at Penn State. Additional thanks go to Dr. Rich Marini and Nicolle Clements for their help with my statistical analyses; to Scott DiLoreto for allowing me to take over his office for use as a laboratory space and for his countless phone calls and emails on my behalf to keep the growth chambers functioning; to Margaret Hoffman for keeping me focused on the big picture while at work; and to Leslie Gentry, Nadine Smith, and my dad, Dr. David Sanford who assisted in collecting data for additional studies at the Penn State Berks Campus. Many thanks go to Scott Burk of Scott’s Landscaping for his assistance, time, and materials during the hydroseeding portions of my study; to Benary Seed for supplying the seed for my studies; and to the Department of Horticulture for the financial assistance that made it possible for me to complete my Ph.D.

I would also like to thank my family and friends for their support and understanding during the challenges and successes throughout my research. To my parents, David and Patricia

Sanford, thank you for always believing in and inspiring me, helping in any way possible

(including being my lab and field technicians), and especially Mom, for the countless hours you spent reviewing and editing my dissertation. Final thanks to my loving husband, Christopher

McDavid, for his continuous faith, patience, and support.

Chapter 1

Literature review

Green Roof Transitions Through History

Although green roof technology is not a new concept, it has only recently become popular in North America. The ideas behind green roofs can be traced back to early man, one example being the famous Hanging Gardens of Babylon, which were built around 500 B.C.

Scandinavians and other civilizations adopted green roof concepts and modified them for practical uses including insulating their houses in extreme climates (Osmundson, 1999).

Early green roofs were not always installed for the same reasons as they are today. In poor areas of Germany, due to the economic problems, houses were built with roofs made with tar. However, tar was found to be extremely flammable; therefore, people added sand and gravel to their roofs based on the advice of H. Koch, a roofer who found that sand and gravel diminished the flammability of the tar (Wells, M. and G. Grant, 2004). Soon, airborne seeds found their way onto the roofs where they germinated, creating roofs with vegetation. These vegetative roofs were then intentionally installed instead of those made with tar. As of 1980, many of these roofs were still thriving and were completely waterproof (Kohler and Keeley, 2005).

Germany is given credit for expanding our knowledge of contemporary green roofs as it has been the leader in promoting green roofs through economic incentives. Germany first started the current green roof trend in the 1960s and has since continued advancement through research and incentives (Kohler, 2006). Numerous other European countries are encouraging the use of green roofs, especially in highly developed areas. In North America, Canada and the United

States are both beginning to implement green roof technology. Unfortunately, many of the green

2 roof recommendations, especially those for plant species and methods, were developed in Europe and, due to climate differences, may not be as successful in the United States (Green Roofs for

Healthy Cities, 2005).

In Toronto, Canada, pilot programs for enacting green roof incentives were approved for both 2006 and 2007. The participants in the pilot program installed green roofs for educational and promotional purposes and received $50/square meter for the green roof installations (City of

Toronto, 2008). The major goal of this program was to promote the use of green roofs by educating the public about them while also reducing storm water runoff.

In 2009, Toronto’s City Council adopted an Eco-Roof Incentive Program. This aggressive program, built on the earlier pilot programs, is aimed at reducing Toronto’s greenhouse gas emissions. An eco-roof was defined as either a green roof or a cool roof (one which reflects solar and thermal emissions). In just two years, over 90,000 square meters of eco- roof were installed throughout Toronto (City of Toronto, 2008).

Within the United States, Portland (Oregon), Chicago, Philadelphia, and areas around

Washington D.C. are currently drafting incentive programs for green roofs with proponents looking to increase the number of green roof installations. In addition to incentive programs, some communities are requiring new construction to follow specific green standards. For example, the Department of Defense and General Services Administration requires that all new construction follow the U.S. Green Building Council’s protocols, and in Chicago, Illinois, all new civic facilities must be Silver LEED certified (Greenroofs.com, 2007). Although green roofs are a significant benefit for the environment, much of the legislation and many incentive programs were specifically created for producing green buildings, not simply installing green roofs.

However, in order for green roofs to be installed in greater numbers, research is needed to learn how to reduce the costs for creating and maintaining a green roof, as well as how to revitalize a green roof to make it as lush as when it was initially installed.

3 Green Roof Basics

Green roof benefits

Research has shown many benefits are derived from green roofs that positively impact both people and the environment. Green roofs reduce storm water runoff and the associated problems with storm water and sewage systems, improve rain water and air quality, reduce the effect from urban heat islands, and act as a thermal damper/evaporative cooler, which decreases heating and cooling costs. Other benefits include extending the life of a roof, creating natural habitats for birds and insects, and improving people’s psychological state and productivity levels.

The reduction in storm water runoff by green roofs is significant with 40 to 60% of annual rain water retention when the roof media is at least 100 millimeters (four inches) deep

(Moran, et al., 2004 and Denardo, et al., 2005). Green roof vegetation also filters and cleanses the water. Both the retention of water and the filtering properties of the vegetation greatly assist combined sewage systems by preventing them from being overwhelmed by large amounts of water. The addition of vegetation on a roof increases water retention and increases the evapotranspiration from the roof (Berghage, et al., 2007). The amount of carbon dioxide in the atmosphere is also reduced when green roofs are utilized because the photosynthetic properties of the vegetation convert carbon dioxide into oxygen. Photosynthesis is so effective in plants that just 1.5 square meters of uncut grass can provide enough oxygen to meet a person’s requirement for a year (Peck, et al., 1999). Green roof plants (in the amount of one square meter) can also remove 0.2 kilograms of potentially harmful particles from the atmosphere each year (Peck and

Kuhn, 2001). Although green roof plants photosynthesize at a slower rate than uncut grass, green roof vegetation still provides large amounts of oxygen and cleanses the air, especially when

4 compared to a non-green roof. High photosynthesis and air cleansing levels are essential to improving the health of the environment, as well as people.

Another environmental benefit of green roofs, mostly observed in cities, is the reduction in the urban heat island effect (Figure 1). The urban heat island effect is defined as an increase of up to 5.6°C (10°F) in temperatures in and around cities due to the impervious and reflective surfaces such as asphalt and roofing materials (United States Environmental Protection Agency,

2011). Adding an extensive green roof to a building can reduce its surface temperature from an average of 65.6°C (150°F) to 25°C (77°F) in mid-July (Ball Publishing, 2006). The heat from a hot roof warms the interior of the building, while a cooler roof prevents such an effect. Reducing the roof temperature reduces the amount of energy needed to heat and cool the building and, in turn reduces air pollution and greenhouse gas emissions. Reducing the roof temperature also helps lessen the urban heat island effect in cities (National Roofing Contractors Association,

2007).

Figure 1-1. Urban heat island effects in a variety of locations (United States Environmental Protection Agency, 2011).

5 As stated, the roof temperature significantly affects the amount of energy required to heat or cool a building. Adding a vegetative layer to the roof provides an additional insulation factor and further reduces the amount of energy required to heat or cool a building (Wells and Grant,

2004). In addition to conserving energy and thus producing less air pollution, reducing the amount of energy required to heat or cool a building can save a significant amount of money.

One study in Toronto, Ontario, predicted that citywide cooling costs would be reduced by $21 million per year when 50 million square meters of green roofs were installed (City of Toronto,

2008). The added insulation provided by green roofs reduces costs and significantly improves the environment, since fewer pollutants from cooling units are released into the atmosphere.

Furthermore, research has shown that green roofs can extend the life of a roof two to three times that of a traditional roof. Traditional roof surfaces deteriorate faster than green roofs because more solar radiation, specifically UV light, reaches the roof’s substrate. However, a green roof absorbs solar radiation and prevents it from reaching the roof’s membrane so the membrane under the vegetative layer does not contract and expand as frequently as a traditional roof. It is this contraction and expansion combined with UV exposure that ultimately leads to the deterioration of roof surfaces (Snodgrass, 2006 and Voelz, 2007).

Although green roofs will not replace an undisturbed natural habitat at ground level, they are superior to an impervious roof surface. Some green roofs are designed to imitate the natural habitat for a specific species of bird or insect. One such roof, the Toronto City Hall

Demonstration Project, was created as a Black Oak Prairie Ecosystem for native butterflies (Peck and Kuhn, 2001). In many situations, habitat creation is not a priority of the roof, but insects, birds, and other wildlife often colonize there. In addition to acting as habitats for wildlife, endangered plant species are sometimes incorporated into green roof designs.

All of the previously stated benefits of green roofs improve the environment, protect wildlife, and save money. But yet another significant benefit of green roofs is how they can

6 directly influence the physiological state of people. Research conducted at a hospital in

Pennsylvania showed the positive impact of nature on patients’ recovery time. In the study, 23 patients had a window in their recovery room overlooking a landscape, while 23 other patients had a window in their room facing a brick wall. Although the sample group was small, the data showed that patients in rooms with a view of nature had significantly shorter hospital stays, were in better spirits towards others, and required less pain medications, when compared to the patients whose rooms had no such view (Ulrich, 1984). In urban settings, people often only view hard, concrete settings such as rooftops, streets, etc. when they look out their windows, but viewing nature in the form of green roofs may have a positive physiological effect on individuals. It is thought that happier people may also be more productive due to their improved state of mind.

Green roof design options

Green roof designs vary across the world and offer various configurations and plants, which are successful in specific climates and locations. The designs can be created simply for the ecological benefits or can include more detail for aesthetic benefits (Luckett, 2009). Green roofs can consist of varying shades of green or include bright hues and colors of yellows and reds.

They can also act as vegetable, herb, and flower gardens, parks, and spiritual healing areas.

The design of a green roof needs to incorporate many details and address: (1) the goal of the landscape and its accessibility for the public, (2) the desired price, and (3) whether it is being installed on an existing or a new building. Within the green roof design, the first decision to be made should be whether to use extensive (shallow) or intensive (deeper) medium as this determines the types of plants that will thrive in the environment.

The second decision should address the price range as this determines whether the roof will be designed with just the basics or with upgrades in structure and planting materials. One

7 upgrade that will likely become more prevalent in upscale green roofs is the installation of an

Electronic Field Vectoring Mapping (EFVM) system. Swarthmore College, a private college located outside of Philadelphia, Pennsylvania, recently installed this system on a green roof. It provides easy leak detection and can determine, within a few feet, the location of a pin-sized leak.

Although this technology comes at a price, it is very beneficial for quickly finding leaks and thus can easily pay for itself.

The third decision should address whether the green roof will be installed on an existing or a new building. Installing a green roof on an existing building is often more complicated because of load-bearing issues; however, significant success has been achieved by the industry in updating existing buildings to withstand the weight of a green roof, with recent research showing ways to reduce the weight load of the media and the plants. The installation of a green roof is, of course, much easier on a new building because the load-bearing issues can be addressed during the early phases of building construction. Since major construction involves the use of large equipment, it can also be used to transport materials to the roof, which can result in significant savings in time and money.

The aforementioned design considerations are not the only ones that need to be considered when installing a green roof, and each roof requires careful evaluation of its unique characteristics prior to creating a design.

Green roof construction

A green roof can be constructed with either an extensive or an intensive design. Both have advantages and disadvantages but the paramount function of the green roof weighs heavily in deciding the method that will be the most beneficial and successful.

8 Extensive green roofs have less than 15 centimeters (6 inches) of substrate, while intensive green roofs have much deeper substrates. Deeper substrates allow for gardens and public places to be created where a wider variety of plants can be utilized, such as trees, shrubs, and herbaceous plants. The extensive roofs (shallow substrate) are mainly used for their environmental benefits and only a limited variety of plant materials can be utilized with them.

The most common plants used on extensive green roofs are annuals, perennials, herbs, and succulents, which typically require minimal maintenance. Extensive green roofs often have lower construction and maintenance costs and can be built on sloped or flat roofs. Intensive green roofs are typically limited to flat roof lines and may require frequent irrigation in addition to maintenance, which increases costs, but both are needed for the more diverse plant material to survive (Snodgrass, 2006 and Elevated Landscape Technologies, Inc., 2006).

There are several different installation practices for green roofs in the United States but a typical green roof has several layers below the media. The layers of a typical green roof consist of the following (starting from the undermost layer): (1) structural support, (2) roofing membrane, (3) insulation, (4) drainage layer, which also may act as a root barrier, (5) growing medium, and (6) the vegetation layer.

Within these layers, the structural support comes from inside the building on which the green roof is installed. The roofing membrane and insulation layers are usually constructed from concrete, wood, metal, plastic, or another similar material. Each material has its advantages and disadvantages, mostly related to price and time of degradation. For additional insulation and the waterproofing layers, there are many different options including layering organic material with asphalt, single-ply sheets of inorganic materials, or liquid-applied membranes. The waterproofing layer is the most important layer and must be completely watertight or the green roof will not be successful and structural damage can occur to the building. The drainage layer prevents the plants from rotting from excess water buildup and often consists of an installed drain

9 to capture the excess water. Again, the options for drainage systems are diverse and can be simple or complex depending on the climate and roof design (Snodgrass, 2006).

The final two layers include the growing medium and the vegetation layer. The vegetation layer will depend on the type of medium used and its depth. Most often, the medium is a light-weight substrate that holds the necessary nutrients, water, and oxygen. The medium is also mostly inorganic so it will not degrade over time. Materials used in the medium typically include expanded slate, shale, or clay; baked clay; volcanic pumice; and/or sand. About 10-25% of the medium should consist of organic compost that provides nutrients. Sand should not be used for the organic compost portion because it can interfere with the drainage systems

(Snodgrass, 2006).

Planting considerations

The majority of plants selected for placement on a green roof are herbaceous annuals, perennials, herbs and succulents. These plants are most successful on intensive green roofs because of the deeper substrate; however, some species can also be incorporated into extensive green roofs with care. In addition, native and endangered plants are also being used on green roofs, which can increase the chances of survival of these plant species.

Annuals are mostly used as accents on roofs while perennials are the main source of plant material. Although annuals allow for color accents on roofs, they may not be cost effective in the long run because they require seed reproduction to continue to flourish year after year and the harsh environmental conditions on a roof may reduce seed viability of many plant species.

Within perennial selections, herbaceous perennials also create splashes of color and provide texture on green roofs. These are often used for aesthetic value and are more beneficial than annuals because they do not require seed reproduction to continue to flourish each year.

10 Unfortunately, many herbaceous perennials often cannot withstand harsh green roof conditions, such as intense heat and drought. Some of the herbaceous perennials, including herbs, which are successful on green roofs are Dianthus, Phlox, Campanula, Allium, Achilla, Salvia, and

Lavandula (Snodgrass, 2006). Herbs are becoming more commonly used on green roofs, especially on structures used as restaurants and hotels. Of note is the financial savings achieved by the Fairmount Waterfront Hotel in Vancouver after their installation of a vegetable, flower, and herb garden on its roof. The hotel has estimated that its yearly savings on vegetables and herbs is over $30,000 (Hansen and Zenobia, 2011).

It is more challenging to select a diversity of plants for extensive green roofs because the plants must grow in a shallow medium. As previously mentioned, these roofs are often created for the environmental benefits more than for their use as a landscape. The most successful plants for these types of spaces are hardy succulents, including Sedum, Sempervivum, Talinum, and

Delosperma (Snodgrass, 2006). These plants are able to survive drought better than herbaceous plants because they can use the Crassulacean Acid Metabolism (CAM) process of metabolism during times of water stress. This process is different from that used by other herbaceous plants as CAM plants reduce water loss by opening their stomata at night, which reduces the amount of transpiration and subsequent water loss because the plant is cooler at night than during the day.

During the day, the stomata are kept closed so less water is lost (Taiz and Zeiger, 2002).

Currently in the United States several procedures are used for installing plant material on a green roof. The main procedures include cuttings/plugs, nursery containers, vegetative mats, and modules. Unfortunately, seed installations are extremely rare, especially on large green roofs.

Cuttings or plugs are most commonly used in providing plant material to green roofs.

Cuttings are often used because they are typically inexpensive and can be easily broadcast onto the surface. However, cuttings typically require frequent irrigation. Plugs are more expensive as

11 more labor is required to individually plant each plug. It is recommended that plugs receive irrigation if planted during the hot, dry summer months (Snodgrass and McIntyre, 2010).

Cuttings and plugs are generally both used because they are more successful than seeds and cheaper than some other methods. In general, each Sedum plug will cost about $0.50 to $0.75 and can immediately provide some color to the roof surface, a desirable attribute for many customers.

Another method for providing vegetation on a green roof is the use of nursery containers.

These containers are used when a larger plant is required on the roof surface. Due to the size of the containers, which range from 2” to gallon pots, usually only a few of these plants are used on a roof surface. Many factors need to be considered when planting nursery containers on roofs including the differences in nursery media versus green roof media. Nursery media is typically composed of organic materials that tend to decompose and are also significantly different than green roof media. Consequently, an interface is often created at the boundary area between the two different media. This interface causes root growth resistance and increases the tendency of the nursery medium to dry out due to capillary and bulk density differences in the media.

Additionally, the plants’ acclimatization requirements for the thinner substrate depth and also different environmental conditions can influence their success rates (Snodgrass, 2006).

Vegetative mats are a more expensive installation method for green roofs and are often used when instant gratification and plant establishment are desired. The plants are typically grown on Enkadrain®, or a similar water distribution mat, and then laid directly on the ground.

After the plants are established in the mats, which may take up to a year, the roots are cut between the mat and the ground, unless the mats are grown on impervious surfaces, in which case the roots cannot attach themselves to the ground. The mats are then rolled up and transported from the production facility to the intended roof surface for installation. Unfortunately, these mats are not only very heavy, but also difficult to ship long distances without refrigeration. In

12 addition, the mats do not tolerate being stored in a rolled condition for more than a day or two.

The main advantage for using mats is that they can be placed on a roof and within a very short period of time will have the appearance of having been there for several years. These mats can also be designed so a specific pattern of plants and/or colors is visible. The main disadvantages for using mats are the weight, although newer techniques are significantly reducing the weight, and the price, which is higher than other planting methods due to the space and maintenance required by the producer, as well as possible shipping costs (Snodgrass and McIntyre, 2010).

Currently, another one of the more expensive options for installing vegetation on a green roof is the use of modules. These are typically plastic squares or rectangles that contain media and vegetation. Two positive features of modules are that the plants can be fully grown for complete coverage and the modules can easily be replaced. In the event that one of the modules dies, having the option of replacing it quickly and easily is very advantageous to the property owner (Snodgrass, 2006). Some disadvantages of modules are that they can be difficult to ship and are often very heavy and awkward to carry. They also require significant space in the nursery to grow prior to shipment.

Today, seeds are not a popular or efficient method for installing vegetation on green roofs in the United States. This is due mainly to the low success rate of the seeds and seedlings, as well as the longer time required for their establishment on the roof. Unpublished research has shown that seeds can be successfully used for green roof installation, but only when planted for a short period of time in the spring. If this successful planting time period could be extended, possibly through quicker germination and less influence of roof conditions on the germination, seeds could become a more viable installation option. One of the leaders in the green roof industry in the

United States, Ed Snodgrass, has stated, “Market pressures to decrease installation costs are causing more thought to be given to direct sowing on green roofs, and with the proper mix of hand broadcasting and hydro-seeding equipment, direct sowing could become a viable – and the

13 least expensive – planting method.” (Snodgrass, 2006). One of the most expensive parts of green roof installations involves the cost of labor. By providing a quick and easy way to install plant material on the roof, such as through the use of seeds, such costs could be drastically reduced

(Pictorial Meadows Seeds, 2009).

Another option for utilizing seeds on a green roof is for older roofs that are in need of revitalization. Over time, green roofs can lose their ornamental plant cover and bare spots can eventually form. Finding a technique to apply seed as an over-seeding method on such a roof would enable a quick and inexpensive revitalization.

Unpublished research by this author found that one of the biggest challenges to utilizing seed on a green roof is the potential movement of the seed. One option that may help prevent seed movement is using a hydromulch. Hydromulch is used in the turf industry specifically to keep grass seed in place but it can be used with many other seed species as well. Hydromulch is composed of a slurry of seed and mulch and is spread using a specialized machine known as a hydroseeder. It often contains a tackifying agent to adhere the seed and mulch to each other.

Hydroseeding has many upsides; not only is it a quick and efficient method to seed large areas, but it is also a stabilizer, holding the seed in place.

Seed Germination

The specific definition of seed germination can vary from reference to reference, although the generally accepted definition, especially when considering seed germination studies, is considered the time until radicle emergence (Nicolas, et al., 2003). Seed germination occurs in three major steps. First, there is a rapid increase of water (imbibition); second, a lag phase occurs; and third, there is radicle emergence. In order for germination to occur, seeds must be viable, subjected to the appropriate environmental conditions, and any dormancy must be

14 overcome. Seed germination is influenced by temperature, moisture level, light, and gas exchange. Lack of any of these factors can prevent seed germination.

Each seed species may vary in its optimal temperature requirement for germination.

Temperature variations in nature help regulate the timing of seed germination. Seeds have a minimum, optimum, and maximum temperature range during which adequate germination will occur. Optimum temperature is defined as the temperature that produces the highest number of seedlings in the shortest amount of time (Hartmann, et al., 2011). Temperatures that are too low or too high can reduce or inhibit seed germination and can cause physiological injury to seeds and/or secondary dormancies.

Moisture levels are also extremely important in seed germination. Without adequate moisture levels during the germination process, seeds cannot imbibe enough water to develop and germinate. Additionally, seedlings are not as tolerant of unfavorable conditions as are mature plants, and seedlings continue to require adequate moisture levels for several days to several months following radicle emergence (Hartmann, et al., 2011). Because seeds are non-mobile and do not have established root systems, they can only acquire water that is directly next to them in a medium. If the water content around the seed is not replenished after initial seed imbibition, the seed can enter secondary dormancy or death.

Unlike temperature and moisture levels that have optimal ranges, light may or may not be required by seeds. Light responses in seed germination are very species specific. Some seeds may not require light and can germinate in complete darkness, yet others may have their germination inhibited by light. Previous unpublished research by this author demonstrated that light tends to have no effect on Sedum seed germination rates.

Although research has studied several gases and their effects on germination, oxygen has been shown to play the most important role. Oxygen is required for respiration in germinating seeds. Without adequate oxygen levels in a germinating seed, the physiological processes cannot

15 occur and radicle emergence may be prevented. Priming solutions are often aerated in order to allow for gas exchange during priming (Hartmann, et al., 2011).

Germination Tests and Seed Maturation

Germination tests are often used to determine the viability of seeds. A germination test is performed by simply placing a specified number of seeds in an optimal environment. It is important to know the length of time needed for germination of the species being tested. Sedum seeds generally germinate within a week or two. Seeds that fail to germinate are considered either dormant or dead (Hartmann, et al., 2011). Seed germination study results are typically recorded in final germination percentages (after a specific amount of time) and the time to 50% germination, often referred to as the T50 (Baskin and Baskin, 1998).

Seeds are frequently stored for varying amounts of time after harvest and prior to use.

Every seed species has a predetermined lifespan, which is based on the storage conditions and rate of deterioration (Kigel and Galili, 1995). Seeds are considered either recalcitrant or orthodox depending on their storage requirements. Recalcitrant seeds do not tolerate drying and must be stored so seed moisture levels are at or above 25%. Orthodox seeds, however, can tolerate drying and can be stored at very low moisture levels for many years. Sedum seeds are orthodox seeds.

Orthodox seeds that are stored under low humidity and at low temperatures can often survive for many years (Hartmann, et al., 2011).

Seeds from most species should be used as soon as possible after harvesting because they may undergo physiological changes when stored in room temperatures over time, which can result in lower germination rates. According to Baskin and Baskin (1998), “It is possible to slow the rate of physiological changes by storing them dry at low temperatures.” It is still recommended to run germination tests throughout the storage time to ensure the seeds are not

16 undergoing physiological changes while in low temperatures. Some seeds will increase germination rates after being stored in a dry, cool area, such as Veronica anthelmintica. In one study, Veronica anthelmintica seeds stored at 0.56°C (33°F) for 24 weeks did not come out of dormancy, but up to half of the seeds germinated after 96 weeks in storage (Baskin and Baskin,

1998). Currently, there are no published data on seed storage affecting seed germination rates of

Sedum species.

Seed Enhancement Technologies

The terms seed treatment or seed enhancement refer to specific techniques that enhance seed germination (i.e. seed priming) or to any type of treatment applied to a seed (i.e. pelleting).

Seed priming is one of the most common seed treatments and it can include many different techniques. The common seed priming techniques include hydropriming, osmopriming, halopriming, thermopriming, and solid matrix priming. Each priming method has its own advantages and in some cases, potential for disadvantages (Ashraf and Foolad, 2005).

Seed priming affects the three major phases of germination. During the first phase of seed germination, large amounts of water are imbibed and few metabolic processes occur. In the second phase, also known as the lag phase, there is little imbibition but high metabolic activity.

In the final phase, there is an increase in water content coinciding with radical growth and emergence (Hartmann, et al., 2002). In general, seed priming is defined as partially hydrating a seed to where the first two phases of the germination processes begin but the seed does not enter into the third phase. Typically, the seeds are re-dried before use, and when rehydrated, show rapid germination under both normal and stressful conditions (Ashraf and Foolad, 2005).

The goal of seed priming is to enhance seed germination. Some of the benefits of priming are earlier radicle emergence, higher germination at sub- and supra-optimal temperatures,

17 more uniform germination, and higher germination rates under stressful conditions (Copeland and

McDonald, 2001). With successful priming, the time to reach 50% of the maximum germination

(T50) can be decreased by up to a third or more, depending on the species (Halmer, 2008).

Hydropriming, also referred to as “on farm seed priming” consists of soaking seed in water before sowing. Hydropriming is also referred to as osmoconditioning (not to be confused with osmopriming, which utilizes chemical treatments). One method to hydroprime seeds consists of merely soaking the seeds in water for a specific amount of time, but this can result in uneven hydration and germination, as well as leakage of nutrients due to the rapid hydration. A second method that prevents the previously mentioned disadvantages is called seed humidification. Seed humidification uses high humidity to begin the seed germination process within the seeds. A final method for hydropriming is called aerated hydration. This is the most common method of hydropriming because a special high humidity chamber is not required and the seeds will still receive the required high oxygen levels during seed soaking (Basra, 2006).

Osmopriming consists of soaking seeds in sugar, polyethylene glycol (PEG), glycerol, sorbitol, or mannitol solutions. The low water potential of the treatment solution allows the seeds to begin the germination process without actually germinating (Ashraf and Foolad, 2005). PEG is one of the most common osmopriming solutions and various concentrations of low osmotic potential solutions can be created. Priming seeds in a solution with a low osmotic potential allows the seeds to slowly imbibe the solution, often maintaining the balance of oxygen and water within the seeds better than a standard pure water solution.

Halopriming is a treatment process where the seeds are soaked in varying concentrations of inorganic salts. This method is very successful for planting seeds in salt-afflicted soils

(Ashraf, et al., 2008). Thermopriming is another pretreatment method that utilizes one of the other common priming methods in varying temperatures. For example, osmopriming seed in a polyethylene glycol solution at a low temperature can result in significantly different germination

18 responses than seed in the same solution primed at a high temperature. Thermopriming is successful for seeds that exhibit thermoinhibition as it is thought to increase their optimal temperature, decreasing the chance for thermodormancy (Halmer, 2008).

Solid matrix priming, also known as matriconditioning, uses a solid matrix instead of an osmotic solution. Treatments typically range from seven to 14 days. Some typical materials used are vermiculite, lignite, coal substances, peat moss, sand, or clay (Copeland and McDonald,

2001). The choice of solid material is important because there are differences in pH and chemical compositions (Ashraf and Foolad, 2005).

Factors that affect seed priming include the length of pretreatment, the temperature of the pretreatment, and the type of priming. The length of the priming may depend on the hardness and thickness of the seed coat. Temperature during priming has also been shown to affect the success of the treatment. The optimization of priming treatments involves significant time and labor to determine the exact time, temperature, and concentration that works best for a specific species.

Seed Species

The main seed species used throughout this study were Sedum acre, Sedum forsterianum,

Sedum reflexum, Sedum selskianum, and Sedum spurium. The recommendations for germination conditions of each of these species are listed as 20°C (68°F) with constant moisture (Benary,

2009). Beyond these recommendations, there is very little published research about other germination recommendations and the germination rates of these seeds at various temperatures.

19 Sedum acre

Sedum acre, a member of the Crassulaceae family, is identifiable by its short, broad- based leaves with paper-like dead leaves that persist on the lower portions on the plant. Sedum acre was used for medicinal purposes in ancient times for intestinal problems. It is native to

Europe, western and northern Asia, and North Africa (Stephenson, 2002 and Snodgrass, 2006). It is recommended for growth in full sun and plants may die back during a hot, humid summer

(Snodgrass, 2006).

Sedum forsterianum

Sedum forsterianum, also a member of the Crassulaceae family, is a succulent, xerophitic plant. It is identifiable by its short, rosette-like tufts of leaves. Indigenous to western Europe, it is most commonly found on damp, rocky areas but also grows well in warm, partially shaded areas (Stephenson, 2002). For green roofs that receive partial shade where plant options are minimal, Sedum forsterianum is an excellent choice.

Sedum reflexum

Sedum reflexum is also known as Sedum rupestre and Petrosedum reflexum. Sedum reflexum is a member of the Crassulaceae family and is identifiable by its sturdy, upright appearance with tall inflorescences (Natural Resources Conservation Service, n.d.). It is native to central and western Europe. Sedum reflexum is one of the most commonly used green roof plants in the United States as it prefers the dry climate of the roof (Stephenson, 2002 and Snodgrass,

2006).

20 Sedum selskianum

Another species of the Crassulaceae family, Sedum selskianum is easily identifiable by its hairy parts. It has its origins in northern China, southern Mongolia, Kazakhstan, and Russia

(Snodgrass, 2006). Sedum selskianum has been mislabeled for many years, specifically as Sedum ellacombianum. This species prefers full sun and is often very slow growing (Stephenson, 2002).

Sedum selskianum is also called Phedimus selskianus (Natural Resources Conservation Service, n.d.).

Sedum spurium

Sedum spurium, part of the Crassulaceae family, has been widely used for groundcovers for many years. It is also listed under Phedimus spurius (Natural Resources Conservation

Service, n.d.). Being highly cultivated, there are many cultivars available with large, flat leaves that turn any shade of color from dark red to copper to purple. It is native to several areas of

Mexico, Armenia, and northern Iran (Stephenson, 2002 and Snodgrass, 2006). Although the plant is very attractive and has colorful foliage, especially into late fall, it often out-competes other plants so it is recommended that it is used with caution (Stephenson, 2002).

Chapter 2

Objective of dissertation

Although green roofs are becoming increasingly popular in the United States, one of the major limitations to their abundant use is their cost of installation. Within parts of the propagation industry, seeds are used to begin the production process because they are typically less expensive, easier to store, ship, and handle than cuttings; and they also reduce the need for large stock plant areas (Hartmann, et al., 2011). Since most Sedums used on green roofs do not grow very tall, large areas of nursery space are required to maintain stock plants. Some green roof growers have indicated that by mid-summer they have often used up the majority of the cuttings from their stock plants. However, the premise is that if seeds could be utilized in the green roof industry as an installation method, over-seeding option, or even the beginning of the production process in a nursery setting, the initial costs for a green roof could be significantly decreased, even given that seeds may require more time to become well established (Snodgrass,

2006).

Unfortunately, seed practices used in other parts of the propagation industry cannot be directly implemented in green roof situations because of the differences in the medium, the moisture levels, and the temperatures. Seed germination requires optimal conditions, something that green roof media are typically lacking. Reducing the germination time and/or the impact of environmental conditions on seeds for green roof plant species would enable faster plant establishment and increase the likelihood of success of the green roof vegetation. The primary objectives of this dissertation include:

1. Identifying potential plant species for seed installation on a green roof;

2. Developing a priming technique to increase seed germination for the selected Sedum

species under stressful conditions, including temperature, moisture levels, and a

combination of the two;

3. Analyzing the germination rates of the selected Sedum seed species treated with the

developed priming techniques in laboratory, greenhouse, and outdoor green roof

settings;

4. Determining whether hydrospraying primed or unprimed seed onto a green roof is a

viable installation option; and

5. Determining whether seed age affects germination rates of the selected Sedum

species.

Chapter 3

Germination rates of multiple seed species and development of a priming method for Sedum species

Introduction

Currently in the United States there are several procedures for installing plant material on a green roof. The main methods include cuttings/plugs, nursery containers, vegetative mats, modules, and rarely, the use of seeds. Each method has its own advantages and disadvantages, especially relating to cost since one of the most expensive aspects of green roof installations is the cost of labor. Cuttings/plugs and nursery containers are frequently a less expensive method for installing green roofs, but require significant labor for planting. Vegetative mats grown on-site can provide another moderately inexpensive method for green roof installation. However, if grown off-site, vegetative mats can be very expensive. Additionally, vegetative mats are often difficult to transport and damage can quickly occur to the plants if care is not used. Modules are frequently one of the most expensive methods for installing a green roof, particularly if they must be grown off-site for several months prior to installation. Seed installations, although rare, are one of the most inexpensive methods for installing a green roof. By providing a quick and easy way to install plant material on the roof, for example, through the use of seeds, costs could be drastically reduced (Snodgrass, 2006).

Additionally, seeds are currently not a popular method for installing vegetation on green roofs in the United States, mainly because of the low success rate of the seeds and seedlings and the presumed longer time required for their establishment on the roof. Existing research has shown that seeds can be a successful approach for green roof installation, but only for a short

24 period of time in the spring (Snodgrass, 2006). If this time period could be extended, possibly through quicker germination and/or less influence of roof conditions on germination, seeds could become a more viable installation option.

Very few seed species have been identified for use on a green roof. A green roof is a harsh climate for seed germination as moisture may not be always available, temperatures are extreme, and the medium is coarse (which can lead to seed movement). Additionally, there is no published research for seed enhancement techniques, such as priming, on Sedum species, the most commonly used plants on green roofs.

There are multiple seed enhancement techniques available for use with seed species. The terms seed treatment or seed enhancement refer to specific techniques that enhance seed germination (i.e. seed priming) or to any type of treatment applied to a seed (i.e. pelleting). Seed priming is one of the most common seed treatments and encompasses many different techniques.

Factors that affect seed priming include the length of pretreatment, temperature of the pretreatment, and the type of priming. The length of the priming may depend on the hardness and thickness of the seed coat. The optimization of priming treatments requires a substantial amount of time and labor to determine the exact time, temperature, and concentration that works best for a specific species (Ashraf and Foolad, 2005).

The goal of seed priming is to enhance seed germination. Germination is considered the time until radicle emergence and it is tested by running a germination test. A germination test is performed by placing a specified number of seeds in an optimal environment. Seeds that fail to germinate are considered either dormant or dead (Hartmann, et al., 2011). Seed germination study results are typically recorded in final germination percentages (after a specific amount of time) and the time to 50% germination, often referred to as the T50 (Baskin and Baskin, 1998).

Some of the benefits of seed priming are earlier radicle emergence, higher germination at sub- or supra-optimal temperatures, more uniform germination, and higher germination rates

25 under stressful conditions (Copeland and McDonald, 2001). With successful priming, the time to reach 50% of the maximum germination (T50) can be decreased by up to a third or more, depending on the species (Halmer, 2008).

One of the easiest and subsequently most common priming methods is hydropriming, which is also referred to as “on farm seed priming” or osmoconditioning and consists of soaking seeds in water before sowing. There are several methods for hydropriming seeds. One common method consists of merely soaking the seeds in water for a specific amount of time, while another popular method is aerated hydration. However, soaking seeds in water without aeration can result in uneven hydration and germination and also leakage of nutrients because of the rapid hydration.

Seeds soaked in water with aeration, however, may have improved germination because of the available oxygen during hydration (Basra, 2006).

Another common priming technique is osmopriming. Osmopriming consists of soaking seeds in various solutions, one of the most common being polyethylene glycol (PEG). The low water potential of the treatment solution permits the seeds to begin the germination processes without actually germinating by allowing the seeds to slowly imbibe the solution, often maintaining the balance of oxygen and water within the seed better than exclusively a pure water solution (Ashraf and Foolad, 2005).

The purpose of this study was to examine multiple seed species and their respective germination rates under various temperatures to identify several species that held potential for improved germination with seed enhancement techniques for use on a green roof. Additionally, two seed priming methods were developed for five selected Sedum seed species.

26 Methods

Germination tests

Data on seed germination rates at a range of temperatures were collected prior to species selection. Initial research was performed on the germination rates of 36 seed species and cultivars. Seeds were placed in growth chambers wherein each chamber was maintained at one of the following temperatures: 10°C (50°F), 15.6°C (60°F), 21.1°C (70°F), 26.7°C (80°F), 32.2°C

(90°F), or 37.8°C (100°F). The limited availability of seeds restricted each petri plate to ten seeds; however, three replications of each species were tested for a total of 30 seeds per temperature. The petri plates were sealed with parafilm and placed in growth chambers

(manufactured by Hoffman Manufacturing, Inc., Albany, Oregon; Percival Scientific Inc., Boone,

Iowa; or Controlled Environments Ltd., Winnipeg, Canada) that provided continuous cycles of

12 hours of light and 12 hours of dark. The 36 seed species are listed in Table 3-1; germination results for each of the 36 species are listed in Appendix A.

Table 3-1. Scientific and common names of seed species tested.

Scientific Name Common Name Sedum acre Stonecrop Sedum forsterianum 'Oracle' Stonecrop Sedum reflexum Stonecrop Sedum selskianum 'Spirit' Stonecrop Sedum spurium 'Coccineum' Stonecrop Sedum spurium 'Voodoo' Stonecrop Celosia plumosa 'Smart Look Red' Cockscomb Cistanthe grandiflora Rock Purslane Coreopsis grandiflora 'Rising Sun' Tickseed

Coreopsis grandiflora 'Presto' Tickseed Dianthus gratianopolitanus 'Flavora Rose Shades' Maiden Pinks Dianthus deltoides 'Confetti White' Maiden Pinks Dianthus deltoides 'Confetti Carmen Rose' Maiden Pinks Dianthus deltoides 'Confetti Deep Red' Maiden Pinks Dianthus deltoides 'Confetti Cherry Red' Maiden Pinks Gaillardia x grandiflora 'Arizona Sun Apex' Blanket Flower Gaillardia aristata ‘Mesa Yellow' F1 Blanket Flower Hypericum cerastoides 'Silvana' Hypericum Lavandula angustifolia 'Vicenza Blue' Lavender Lavandula angustifolia 'Munstead Variety' Lavender Pentas lanceolata 'F1 Kaleidoscope Pink' Starcluster Physostegia virginiana 'Crystal Peak White' Obedient Plant Prunella grandiflora 'Freelander Blue' Prunella Prunella grandiflora 'Freelander Mix' Prunella Ptilotus exaltatus 'Joey' Pink Mulla Mulla, Lamb's Tail Rudbeckia hirta 'Cappuccino' Blackeyed Susan Rudbeckia hirta 'Maya Apex C' Blackeyed Susan Rudbeckia hirta 'Tiger Eye Gold' Blackeyed Susan Salvia farinacea 'Fairy Queen' Mealycup sage, Salvia Sanvitalia speciosa 'Million Suns' Mexican Creeping Zinnia Viola wittrockiana 'Fizzy Lemonberry' Pansy Viola x wittrockiana 'MatrixTM Rose' Pansy Viola x wittrockiana 'MatrixTM Rose Wing' Pansy Zinnia marylandica 'Zahara Coral Rose' Zinnia Zinnia marylandica 'Zahara Scarlet' Zinnia Zinnia marylandica 'Zahara White' Zinnia

28 Species selection

Seed species for further testing were selected based on whether the seeds exhibited one of the following characteristics: (1) poor germination rates at any temperature, (2) significant decrease in germination rates at one of the sub- or supra-optimal temperatures, or (3) average- or above-average germination rates at all temperatures. These characteristics suggested a greater potential for success after applying seed treatments. Poor germination rates at all temperatures may require a seed enhancement technique to improve germination rates. Seed enhancement techniques can alter the optimal temperature of seed germination, enabling seeds with significant decreases in germination rates at one of the sub- or supra-optimal temperatures to improve germination. Finally, although seeds with average- or above-average germination rates at all temperatures have the potential for success on green roofs without any seed enhancement techniques, such techniques may still improve germination rates and establishment. In addition, good candidates were readily available and produced drought tolerant plants.

From the results of the germination tests, five seed species fulfilled the “good candidate” requirements for further testing and seed treatment evaluation. The seed species selected were:

1. Sedum acre (from Benary Seeds)

2. Sedum forsterianum ‘Oracle’ (from Benary Seeds)

3. Sedum reflexum (from Benary Seeds)

4. Sedum selskianum ‘Spirit’ (from Benary Seeds)

5. Sedum spurium ‘Voodoo’ (from Benary Seeds)

29 Design of a successful priming method

Given that no published research existed on seed enhancement techniques for the five selected Sedum seed species, several experiments were performed on each species to create a successful seed enhancement technique. Published research on other seed species indicated that seed priming was most successful when seeds were primed within a few degrees of their optimal germination temperatures (Black and Bewley, 2000). Therefore, the seeds were primed at 18.3°C

(65°F), a temperature similar to the optimal germination temperature for each of the seed species.

Absent any data on recommended time periods for priming, the first experiment used osmoconditioning treatments at multiple time periods, ranging from 12-48 hours and seeds were grown in a 21.1°C (70°F) growth chamber. This experiment helped narrow down an optimal time period for priming.

After the optimal time period for priming was determined, solutions of polyethylene glycol (PEG) were created. PEG is one of the most commonly used priming chemicals and is successful on a wide range of species (Farooq, et al., 2005). The following three PEG solutions were created: (1) a low (-0.2 MPa), (2) a medium (-0.82 MPa), and (3) a high (-1.72 MPa) concentration (Michel and Kaufmann, 1973). Published research on other seed species indicated that concentrations similar to the ones selected were most successful. The three PEG concentrations were tested in conjunction with the priming periods. Due to lack of seed, Sedum forsterianum was not used in this study.

Seeds were primed in small bundles created from handkerchiefs. Handkerchiefs were selected because the small size of the five selected seed species required a tightly woven material that was able to withstand long periods of time in the priming solutions without disintegrating.

Each handkerchief was cut into four equal sections. One hundred seeds (20 seeds for the osmoconditioning study) from one seed species were placed on each of these sections. Each

30 section was folded to form a bundle. The bundles were closed with zip-ties. Seed bundles were primed in separate containers of aerated solutions (Table 3-2) to prevent any possible allelopathic effects from one species to another. After removal from the aerated solutions, the bundles were opened and subjected to a standard gravity filtration that allowed the seeds to be removed from the handkerchiefs and collected on filter papers. The seeds were air dried on the filter papers in petri plates (with lids removed) for at least 24 hours.

After drying, 20 seeds from each bundle were placed in separate petri plates with new filter paper saturated with 1.5 milliliters of water. This provided five replications per treatment per species (only one replication for the osmoconditioning study). Next, the petri plates were double wrapped with parafilm and a full set of treatments (eight treatments and a no-prime control, each with five replications) were placed in the growth chamber at 32.2 degrees Celsius

(90°F).

Table 3-2. List of priming concentrations and length of priming time.

Chemical Concentration Duration of Priming PEG Low (-0.2 MPa) 4 hours PEG Medium (-0.82 MPa) 4 hours PEG High (-1.72 MPa) 4 hours Water Not Applicable 4 hours PEG Low (-0.2 MPa) 12 hours PEG Medium (-0.82 MPa) 12 hours PEG High (-1.72 MPa) 12 hours Water Not Applicable 12 hours

Experimental design, data collection, and statistical analysis

All petri plates in the growth chambers were placed in a completely randomized design and the plates were re-randomized every other day. Data were collected using dissecting microscopes. The seeds were considered germinated when the radicle was at least one quarter the size of the seed. The data were analyzed for each species using a regression analysis in SAS.

31 However, the statistical results of the osmoconditioning study should be used with caution as there were only twenty seeds (and no replications) in each treatment. An optimal seed germination study should contain at least three replications with 25 seeds in each replication

(Geneve, 2009).

Results and Discussion

Development of a successful seed enhancement technique

The data from the osmoconditioning treatments showed that the shorter length of priming times typically resulted in higher germination percentages and several of the seeds germinated during the longest priming period (48 hours), which subsequently killed the seeds when they were re-dried (Table 3-3). There was a negative quadratic relationship between the duration of priming and germination within Sedum acre. This relationship accounted for 95.93% of the variability in the model (p-value of 0.0407). The control, with no priming, had 100% germination. Seeds in the 12-hour water prime had a final germination of 47.6%, and germination decreased as the priming time increased, to a final germination of 28% in the 48-hour water prime. There were insufficient data to run an analysis on Sedum forsterianum with only three different priming times

(including the control) and there were not enough data points to make a conclusion on a trend; although, final germination in the 24-hour and 36-hour water primes were under 22%. This was much lower than the Sedum forsterianum control seeds which germinated at 85%. Within the

Sedum reflexum results, as the duration of the priming time increased, seed germination decreased following a quadratic model (r-squared = 0.9762, p-value = 0.0238). Seed germination in the control, 12-hour water prime, and 24-hour water prime were all equal at 95%. The 36-hour water prime and 48-hour water prime had germination percentages of 90% and 77.8%, respectively.

32 Data from Sedum selskianum had a negative linear relationship between the duration of the priming and germination (r-squared = 0.8643, p-value = 0.0506). Germination decreased from

100% (control) to 95% (12-hour water prime and 24-hour water prime) to 80% (36-hour water prime and 48-hour water prime). Data for Sedum spurium fit a negative cubic equation with an r-squared value of 0.9984. The control had the highest germination, at 85%. The 12-hour water prime had the next highest germination but significantly lower, at only 38.9%.

In general, as the length of the priming time increased, seed germination decreased. The germination rates in the control treatments were far superior in three of the five seed species, leading to a conclusion that even a 12-hour water prime may have been too long for these seeds.

Table 3-3. Final germination percentages for each species in different priming times.

Length of Sedum Sedum Sedum Sedum acre Sedum reflexum Priming Time forsterianum selskianum spurium Control 100% 85.0% 95.0% 100% 85.0% 12 hour 47.6% (0/21) --- 95.0% (0/20) 95.0% (0/20) 38.9% (0/18) 24 hour 35.0% (0/20) 15.0% (0/20) 95.0% (0/20) 95.0% (0/20) 31.6% (0/19) 36 hour 30.0% (0/20) --- 90.0% (0/20) 80.0% (0/20) 30.0% (0/20) 48 hour 28.0% (7/25) 21.7% (1/23) 77.8% (2/27) 80.0% (3/25) 18.2% (0/20) Note: Numbers in parentheses are the amount of seeds that had radicle emergence while in priming solutions.

To further identify a priming time period that would be successful at producing higher germination rates, a combination of lower priming time periods and PEG solutions were tested.

When combined, the data for the 4-hour, 8-hour, and 12-hour priming periods and the low (-0.2

MPa), medium (-0.82 MPa), and high (-1.72 MPa) PEG concentrations showed no significant differences in germination rates among treatments in most species.

For Sedum acre and Sedum reflexum, multiple regression analysis indicated that the proportion of germinated seeds was not related to PEG concentration, the amount of time seeds were primed, or the interaction between the PEG concentration and the length of priming time

33 (r-squared values of 0.1149 and 0.0014, respectively). The means for the final germination rates are shown in Tables 3-4 and 3-5, respectively.

Table 3-4. Sedum acre germination in differing concentrations of PEG and priming times.

Priming Time / No PEG -0.2 MPa PEG -0.82 MPa PEG -1.72 MPa PEG PEG conc. No prime (control) 86.0% ------4 hour 84.0% 87.0% 76.0% 73.0% 8 hour 72.0% 69.0% 80.0% 70.0% 12 hour 79.0% 82.0% 84.0% 84.0%

Table 3-5. Sedum reflexum germination in differing concentrations of PEG and priming times.

Priming Time / No PEG -0.2 MPa PEG -0.82 MPa PEG -1.72 MPa PEG PEG conc. No prime (control) 71.0% ------4 hour 75.0% 69.0% 57.0% 79.0% 8 hour 68.0% 71.0% 71.0% 78.0% 12 hour 81.0% 60.0% 67.0% 68.0%

The exponential function of the Sedum selskianum data was used to fit regression assumptions. There was a significant exponential relationship for PEG germination results and it was found that as the PEG concentration increased, germination also increased (r-squared =

0.0822, p-value = 0.0206; Figure 3-1). However, final germination percentages for all treatments were above 92%. The mean final germination for the treatments without PEG was 92.5%; the mean final germination for the low PEG (-0.2 MPa) treatments was 96.7%; the mean final germination for the medium PEG (-0.82 MPa) treatments was 96.3%; and the mean final germination for the high PEG (-1.72 MPa) treatments was 97%. Multiple regression analysis run on the data showed no significant difference for the length of the priming or the interaction of the

PEG concentration and priming time (Table 3-6).

Sedum selskianum Germination

96.0%

95.5%

95.0%

94.5%

94.0%

93.5%

93.0%

92.5% Germination Percentage (at day21) (at Percentage Germination 92.0% -2 -1.5 -1 -0.5 0 PEG Concentration (in MPa)

Germination

Figure 3-1. Sedum selskianum seed germination at day 21 in relation to the PEG concentration.

Table 3-6. Sedum selskianum germination in differing concentrations of PEG and priming times.

Priming Time / No PEG -0.2 MPa PEG -0.82 MPa PEG -1.72 MPa PEG PEG conc. No prime (control) 92.0% ------4 hour 94.0% 98.0% 97.0% 98.0% 8 hour 91.0% 92.0% 95.0% 98.0% 12 hour 93.0% 94.0% 97.0% 95.0%

Multiple regression analysis on Sedum spurium data resulted in a significant interaction between the PEG concentration and the duration of the priming period with an r-squared value of

0.1265 and p-value of 0.0399 (Figure 3-2 and Table 3-7). Seeds in the control germinated the best, at 85%. Seeds treated with a 4-hour, 8-hour, or 12-hour water prime, as well as seeds primed for four, eight, or twelve hours with the highest PEG concentration of -1.72 MPa, germinated at lower percentages than seeds primed with the low (-0.2 MPa) or medium (-0.82

35 MPa) PEG concentrations; although all germination percentages were at least 15% lower than the control germination.

Sedum spurium Germination 100.0% 90.0%

80.0% 70.0% 60.0% Water 50.0% -0.2 MPa PEG 40.0% -0.82 MPa PEG 30.0% -1.72 MPa PEG

Germination Rate (at 21 days)21 (at Rate Germination 20.0% 10.0% 0.0% 0 4 8 12

Soak Time (in hours)

Figure 3-2. Sedum spurium seed germination at day 21 in relation to the interaction of both priming time and the PEG concentration.

Table 3-7. Sedum spurium germination in differing concentrations of PEG and priming times.

Priming Time / No PEG -0.2 MPa PEG -0.82 MPa PEG -1.72 MPa PEG PEG conc. No prime (control) 86.0% ------4 hour 45.0% 52.0% 52.0% 39.0% 8 hour 53.0% 69.0% 70.0% 65.0% 12 hour 54.0% 63.0% 59.0% 48.0%

36 The data for the amount of time to reach 50% germination (T50) for Sedum acre, Sedum reflexum, and Sedum selskianum did not show any significant regression trends. Again, due to the lack of seed, no data were available for Sedum forsterianum. Multiple regression analysis run on the Sedum spurium data showed a linear relationship between the time to 50% germination and the length of the priming time with an r-squared value of 0.3407 and p-value of <0.0001

(Figure 3-3). As the duration of the priming period increased, the amount of time it took the seeds to reach 50% germination also increased. Thus, since a quick time to 50% germination is ideal, the control had the fastest germination rates, reaching 50% germination in two days.

Sedum spurium Germination 7.0

6.0

5.0

4.0

3.0

2.0 Days to 50% Germination 50% to Days 1.0

0.0 0 4 8 12 Soak Time (in hours)

Time to 50% Germination Predicted (Linear)

Figure 3-3. Sedum spurium data for days to 50% germination in relation to the length of priming.

37 Conclusion

In identifying potential plant species for seed installation on a green roof, the Sedum species had the most desirable characteristics for a green roof plant species as well as potential for improved germination through seed priming. In general, the osmoconditioning experiment

(primed for 12-48 hours) demonstrated that there was a maximum priming period for each seed species and showed that seeds began to germinate in the priming solution when exposed to the solution for too long. Subsequently, seeds died when re-dried after priming. When adding PEG solutions and reducing the priming time in controlled laboratory studies, there was no significant relationship between the primed and control seeds for Sedum acre, Sedum reflexum, and Sedum spurium. Based solely on the laboratory studies, there was no reason to prime any of the three species because the controls germinated at rates at or above treated seeds. Conversely, Sedum selskianum seeds germinated at higher levels in the laboratory studies when primed in PEG solutions with the highest PEG solution (-1.72 MPa) having the highest germination. Overall, although it was determined that priming the five selected Sedum seed species was not cost effective, this study successfully determined the maximum priming periods for the selected species. Additionally, even though the priming treatments did not improve germination in most species when tested at an optimal and a supra-optimal temperature, further testing is necessary to determine whether priming could be successful under other stressful conditions, such as varying moisture levels or a combination of temperature and moisture stress.

Chapter 4

Determining Sedum moisture requirements for seed germination in a greenhouse facility

Introduction

Successful seed germination requires a combination of viable, non-dormant seed and the appropriate environmental conditions. Seed germination is influenced by temperature, moisture level, light, and gas exchange. Each of these factors can prevent germination if adequate conditions are not provided to the seed; however, moisture availability is one of the most critical factors (Hartmann, et al., 2011).

Without adequate moisture levels over the germination period, seeds cannot imbibe enough water to develop and germinate. Seedlings in particular are not as tolerant of unfavorable conditions as are mature plants, and they continue to require adequate moisture levels for several days or months following radicle emergence (Hartmann, et al., 2011). Because seeds are non- mobile and do not have established root systems, they can only acquire water that is in direct contact with them in a medium. If the water content around the seed is not replenished during and after initial seed imbibitions, even for a short period of time, the seed can enter secondary dormancy or die.

Five seed species (Sedum acre, Sedum forsterianum, Sedum reflexum, Sedum selskianum, and Sedum spurium) were selected for this study based on whether the seeds exhibited one of the following characteristics: (1) poor germination rates at any temperature, (2) significant decrease in germination rates at one of the sub- or supra-optimal temperatures, or (3) average- or above-

39 average germination rates at all temperatures. Previous unpublished research by this author showed that these characteristics indicated a potential for higher germination rates after priming with water or polyethylene glycol (PEG) for 4-12 hours prior to being grown in stressful conditions in a laboratory setting. PEG is one of the most common osmopriming solutions and permits a concentration of low osmotic potential to be created. Priming seeds in a solution with a low osmotic potential allows the seed to slowly imbibe the solution, often maintaining the balance of oxygen and water within the seed better than an exclusively pure water solution

(Ashraf and Foolad, 2005).

The purpose of this study was to determine how frequently the five Sedum seed species required irrigation and whether primed seeds reacted to the stressful moisture conditions in the same manner as untreated seeds in a controlled greenhouse environment.

Methods

Species selection

Seed species were selected based on whether the seeds exhibited one of the following characteristics: (1) poor germination rates at any temperature, (2) significant decrease in germination rates at one of the sub- or supra-optimal temperatures, or (3) average- or above- average germination rates at all temperatures. A previous experiment developed a priming method for five Sedum species (Sedum acre, Sedum forsterianum, Sedum reflexum, Sedum selskianum, and Sedum spurium), which were selected based on the aforementioned characteristics. Although the previous experiment demonstrated that untreated seeds germinated as well or better than primed seeds in an optimal and a supra-optimal temperature, priming may allow improved germination in other stressful conditions, such as lower moisture levels. Thus,

40 the same five Sedum species were utilized for this study to determine whether priming could improve germination when seeds were under stressful moisture conditions, but grown at an optimal temperature.

Design of moisture study

A greenhouse experiment was designed to establish a watering regime for the five selected Sedum seed species. Three treatments were used: (1) a mist system, (2) a watering regime of every other day (EOD), and (3) a watering regime of once every four days (E4D). The mist system watered the seeds for six seconds at eight minute intervals, while the other two watering regimes distributed just under two liters of water per flat (equal to one-half inch of water per flat) at their respective watering cycle.

To simulate an extensive green roof situation, flats (36 centimeters (14.1 inches) long x

36 centimeters (14.1 inches) wide x 12.7 centimeters (5 inches) high) were filled with 10.16 centimeters (4 inches) of steam-sterilized green roof media (a sandstone based green roof medium with 9.53 millimeter (3/8 inch) gravel and compost).

Previous unpublished priming experiments by this author on the five selected Sedum species indicated there was no relationship in germination rates when seeds were primed in water or PEG for 4-12 hours in various temperatures. However, research has shown that priming treatments can reduce the water requirements during germination, so there was still a potential for success of priming treatments with water or PEG primed for 4-12 hours when grown in optimal temperatures with varying levels of moisture. Thus, seeds in this study were primed for 4-12 hours either with water or PEG. Seeds were primed in small bundles of material (handkerchiefs).

Handkerchiefs were selected as the small size of the five selected seed species required a tightly woven material that was able to withstand long periods of time in the priming solutions without

41 disintegrating. Each handkerchief was cut into four equal sections. Thirty seeds from one seed species were placed on each of these sections. Each section was folded to form a bundle. The bundles were closed with zip-ties. Seed bundles were primed in separate containers of aerated solutions (Table 4-1) to prevent any possible allelopathic effects from one species to another.

After removal from the aerated solutions, the bundles were opened and subjected to a standard gravity filtration that allowed the seeds to be removed from the handkerchiefs and collected on filter papers. The seeds were air dried on the filter papers in petri plates (with lids removed) for at least 24 hours.

Each flat contained one seed species and the flats were divided into 15 sections, with three replications per treatment, including a no-prime control (Table 4-1). Ten seeds per treatment were mixed with one teaspoon of sand (to facilitate spreading of the seed) and were distributed onto their respective section in the flat, for a total of 30 seeds per treatment.

Table 4-1. Priming solutions for moisture study.

Chemical Concentration Duration of Priming PEG Medium (-0.82 MPa) 4 hours PEG Medium (-0.82 MPa) 12 hours Water Not applicable 4 hours Water Not applicable 12 hours

Experimental design, data collection, and statistical analysis

Within each flat, a completely randomized design was implemented for the moisture study. Seeds were considered germinated when the radicle or leaves were visible on the surface of the media. Within seed germination studies, it is recommended that there be at least three replications with no fewer than 25 seeds in each replication (Geneve, 2009); therefore, with only

30 seeds per treatment (10 seeds per replication), statistical analysis was not run on the collected data.

42 Results and Discussion

Sedum acre germination results for most treatments and watering cycles ranged between

60% and 90% (Table 4-2 and Figure 4-1). The mist treatments tended to have slightly higher germination percentages than the treatments watered less frequently. The lowest germination percentages were found in the 4-hour PEG prime, 4-hour water prime, and control (no-prime) treatments watered every four days. Each of these treatments resulted in only 30% germination, which was much lower than all other treatments in the study. Additionally, the average time to

50% germination in the mist treatments was 4.5 days, while it took an average of 6.4 days and 7.3 days to reach 50% germination in the treatments watered every other day and every four days, respectively (Table 4-3).

Table 4-2. Sedum acre treated and untreated seed germination percentages in differing levels of moisture on day 14. Treatment, Watering Regime Mean Germination Percentage on Day 14 Control (no prime), mist 70% 4-hour water prime, mist 70% 12-hour water prime, mist 80% 4-hour PEG prime, mist 90% 12-hour PEG prime, mist 80% Control (no prime), every other day 73.33% 4-hour water prime, every other day 70% 12-hour water prime, every other day 63.33% 4-hour PEG prime, every other day 60% 12-hour PEG prime, every other day 76.67% Control (no prime), every four days 30% 4-hour water prime, every four days 30% 12-hour water prime, every four days 66.67% 4-hour PEG prime, every four days 30% 12-hour PEG prime, every four days 63.33%

Sedum acre Moisture Study 100.00% 90.00%

80.00%

70.00% 60.00% 50.00% 40.00%

Germination (%) Germination 30.00% 20.00% 10.00% 0.00% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Days

Control Mist 4-H2O Mist 12-H2O Mist 4-peg Mist 12-peg Mist Control EOD 4-H2O EOD 12-H2O EOD 4-peg EOD 12-peg EOD Control E4D 4-H2O E4D 12-H2O E4D 4-peg E4D 12-peg E4D

Table 4-3. Sedum acre time to 50% germination of treated and untreated seed in differing levels of moisture. Treatment, Watering Regime Time to 50% Germination (in days) Control (no prime), mist 4.5 4-hour water prime, mist 4.5 12-hour water prime, mist 4.5 4-hour PEG prime, mist 4.5 12-hour PEG prime, mist 4.5 Control (no prime), every other day 6.5 4-hour water prime, every other day 7.5 12-hour water prime, every other day 5.5 4-hour PEG prime, every other day 6.0 12-hour PEG prime, every other day 6.5 Control (no prime), every four days 6.5 4-hour water prime, every four days 6.5 12-hour water prime, every four days 8.5 4-hour PEG prime, every four days 8.5 12-hour PEG prime, every four days 6.5

44 Sedum forsterianum seeds germinated at the highest percentages when under the mist watering regime (Table 4-4 and Figure 4-2). Similar to Sedum acre seeds, the lowest germination percentages occurred in the every four days watering regime treatments, while the every other day watering regime treatments resulted in final germination percentages lower than the mist treatments and higher than all but one of the treatments watered every four days. Unlike Sedum acre, there were higher germination rates in the top three treatments (4-hour water prime, 12-hour water prime, and control (no-prime) watered under mist) compared with the other treatments, with germination percentages of 93%, 83%, and 83%, respectively. The treatments that were watered every other day (excluding the 12-hour water prime) resulted in lower germination percentages, ranging between 53% and 63%. The final group of data was in the treatments that were watered every four days (and the 12-hour water prime watered every other day), and these resulted in germination percentages between 10% and 27%. Again, these data demonstrated that seeds preferred moist conditions. Additionally, there was up to a five day difference between when seeds in the three watering cycles started germinating. Seed germination started on day four for most of the mist treatments while some of the treatments watered every four days did not start germinating until day nine. This trend is evident in the time to 50% germination as seed germination reached this point between day six and day seven for the mist treatments, while the treatments watered every other day and every four days averaged 9.6 days and 10.4 days as their time to 50% germination (Table 4-5).

45 Table 4-4. Sedum forsterianum treated and untreated seed germination percentages in differing levels of moisture on day 14. Treatment, Watering Regime Mean Germination Percentage on Day 14 Control (no prime), mist 83.33% 4-hour water prime, mist 93.33% 12-hour water prime, mist 83.33% 4-hour PEG prime, mist 70% 12-hour PEG prime, mist 63.33% Control (no prime), every other day 63.33% 4-hour water prime, every other day 53.33% 12-hour water prime, every other day 23.33% 4-hour PEG prime, every other day 60% 12-hour PEG prime, every other day 56.67% Control (no prime), every four days 23.33% 4-hour water prime, every four days 13.33% 12-hour water prime, every four days 10% 4-hour PEG prime, every four days 26.67% 12-hour PEG prime, every four days 23.33%

Sedum forsterianum Moisture Study 100.00% 90.00% 80.00% 70.00% 60.00% 50.00% 40.00%

Germination (%) Germination 30.00% 20.00% 10.00% 0.00% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Days

Control Mist 4-H2O Mist 12-H2O Mist 4-peg Mist 12-peg Mist Control EOD 4-H2O EOD 12-H2O EOD 4-peg EOD 12-peg EOD Control E4D 4-H2O E4D 12-H2O E4D 4-peg E4D 12-peg E4D

46 Table 4-5. Sedum forsterianum time to 50% germination of treated and untreated seed in differing levels of moisture. Treatment, Watering Regime Time to 50% Germination (in days) Control (no prime), mist 6.5 4-hour water prime, mist 6.5 12-hour water prime, mist 6.5 4-hour PEG prime, mist 6.5 12-hour PEG prime, mist 7.5 Control (no prime), every other day 9.5 4-hour water prime, every other day 10.0 12-hour water prime, every other day 9.5 4-hour PEG prime, every other day 9.5 12-hour PEG prime, every other day 9.5 Control (no prime), every four days 11.5 4-hour water prime, every four days 9.5 12-hour water prime, every four days 9.5 4-hour PEG prime, every four days 10.0 12-hour PEG prime, every four days 11.5

Sedum reflexum seeds had the highest germination in treatments watered by mist; however, both the every other day and every four day watering cycles also had high germination in most treatments (Table 4-6 and Figure 4-3). Unlike Sedum acre and Sedum forsterianum, all but two treatments had germination percentages above 66%. Only the 12-hour PEG and 12-hour water primes had germination percentages at or lower than 66%. One note on this data is that the flat watered every four days was closer to the pad side of the fan-and-pad wall and potentially received supplemental moisture from its location. However, overall germination percentages were relatively high in all watering regimes, leading to the conclusion that high moisture levels may not be as important to Sedum reflexum as to other species. When comparing the times to

50% germination, the mist treatments reached 50% germination more quickly, at an average of

4.9 days. Treatments watered once every four days reached 50% germination after an average of

6.6 days, and treatments watered every other day reached this point after an average of 8.0 days

(Table 4-7).

47 Table 4-6. Sedum reflexum treated and untreated seed germination percentages in differing levels of moisture on day 14. Treatment, Watering Regime Mean Germination Percentage on Day 14 Control (no prime), mist 90% 4-hour water prime, mist 90% 12-hour water prime, mist 73.33% 4-hour PEG prime, mist 100% 12-hour PEG prime, mist 90% Control (no prime), every other day 73.33% 4-hour water prime, every other day 76.67% 12-hour water prime, every other day 46.67% 4-hour PEG prime, every other day 86.67% 12-hour PEG prime, every other day 60% Control (no prime), every four days 70% 4-hour water prime, every four days 76.67% 12-hour water prime, every four days 66.67% 4-hour PEG prime, every four days 80% 12-hour PEG prime, every four days 83.33%

Sedum reflexum Moisture Study 100.00% 90.00% 80.00%

70.00% 60.00% 50.00% 40.00%

Germination (%) Germination 30.00% 20.00% 10.00% 0.00% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Days

Control Mist 4-H2O Mist 12-H2O Mist 4-peg Mist 12-peg Mist Control EOD 4-H2O EOD 12-H2O EOD 4-peg EOD 12-peg EOD Control E4D 4-H2O E4D 12-H2O E4D 4-peg E4D 12-peg E4D

48 Table 4-7. Sedum reflexum time to 50% germination of treated and untreated seed in differing levels of moisture. Treatment, Watering Regime Time to 50% Germination (in days) Control (no prime), mist 5.5 4-hour water prime, mist 5.5 12-hour water prime, mist 4.5 4-hour PEG prime, mist 4.5 12-hour PEG prime, mist 4.5 Control (no prime), every other day 8.5 4-hour water prime, every other day 8.5 12-hour water prime, every other day 8.0 4-hour PEG prime, every other day 7.5 12-hour PEG prime, every other day 7.5 Control (no prime), every four days 6.5 4-hour water prime, every four days 7.5 12-hour water prime, every four days 6.0 4-hour PEG prime, every four days 6.5 12-hour PEG prime, every four days 6.5

For Sedum selskianum, the lowest germination percentages were in the treatments watered every four days, while the treatments watered every other day had germination percentages between the mist treatments and the treatments watered every four days. The mist treatments, which had the highest germination percentages, ranged from 83% to 100%. The final germination for treatments watered every other day ranged from 53% to 73%, while the treatments watered every four days (excluding the 4-hour water prime) ranged from 13% to 37%

(Table 4-8 and Figure 4-4). In addition to the final germination differences, there was also up to a five day difference in the length of time it took for radicle emergence to begin. Seeds in all of the mist treatments started germinating at day four, while seeds in the treatments watered every other day and every four days did not begin germinating until days six and seven and days nine and ten, respectively. Additionally, time to 50% germination in the mist treatments averaged 5.5 days, while in the treatments watered every other day and every four days, the averages were 9.1 days and 12.2 days, respectively (Table 4-9). Seeds in the mist treatments reached the highest germination of all watering regimes and reached 50% germination more quickly than others.

49 Table 4-8. Sedum selskianum treated and untreated seed germination percentages in differing levels of moisture on day 14. Treatment, Watering Regime Mean Germination Percentage on Day 14 Control (no prime), mist 83.33% 4-hour water prime, mist 100% 12-hour water prime, mist 83.33% 4-hour PEG prime, mist 90% 12-hour PEG prime, mist 93.33% Control (no prime), every other day 60% 4-hour water prime, every other day 73.33% 12-hour water prime, every other day 66.67% 4-hour PEG prime, every other day 53.33% 12-hour PEG prime, every other day 73.33% Control (no prime), every four days 36.67% 4-hour water prime, every four days 56.67% 12-hour water prime, every four days 16.67% 4-hour PEG prime, every four days 23.33% 12-hour PEG prime, every four days 13.33%

Sedum selskianum Moisture Study 100.00% 90.00% 80.00%

70.00% 60.00% 50.00% 40.00%

Germination (%) Germination 30.00% 20.00% 10.00% 0.00% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Days Control Mist 4-H2O Mist 12-H2O Mist 4-peg Mist 12-peg Mist Control EOD 4-H2O EOD 12-H2O EOD 4-peg EOD 12-peg EOD Control E4D 4-H2O E4D 12-H2O E4D 4-peg E4D 12-peg E4D

50 Table 4-9. Sedum selskianum time to 50% germination of treated and untreated seed in differing levels of moisture. Treatment, Watering Regime Time to 50% Germination (in days) Control (no prime), mist 6.5 4-hour water prime, mist 5.5 12-hour water prime, mist 4.5 4-hour PEG prime, mist 6.5 12-hour PEG prime, mist 4.5 Control (no prime), every other day 8.5 4-hour water prime, every other day 8.5 12-hour water prime, every other day 10.5 4-hour PEG prime, every other day 8.5 12-hour PEG prime, every other day 9.5 Control (no prime), every four days 12.5 4-hour water prime, every four days 12.5 12-hour water prime, every four days 12.5 4-hour PEG prime, every four days 11.5 12-hour PEG prime, every four days 12.0

Sedum spurium germinated at higher percentages when watered under the mist regime or every other day (Table 4-10 and Figure 4-5). The 4-hour water prime under the mist regime produced the best germination, at 100%. The other mist treatments also resulted in high germination, ranging between an average of 83.33% and 93.33%. All of the treatments watered every other day had germination percentages lower than the mist treatments but higher than the treatments watered every four days, ranging from 60% to 80%. The lowest germination percentages were observed in all of the treatments watered every four days. Germination for treatments watered every four days ranged between an average of 26.67% and 53.33%. The time to 50% germination was also faster in treatments watered by mist, averaging 5.5 days to reach this point. Treatments watered every other day averaged 7.8 days to reach 50% germination, while treatments watered every four days averaged 11.1 days to reach 50% germination (Table

4-11). These results show that Sedum spurium seeds prefer moist conditions and will germinate slowly and at lower percentages without adequate moisture.

51 Table 4-10. Sedum spurium treated and untreated seed germination percentages in differing levels of moisture on day 14. Treatment, Watering Regime Mean Germination Percentage on Day 14 Control (no prime), mist 93.33% 4-hour water prime, mist 100% 12-hour water prime, mist 90% 4-hour PEG prime, mist 83.33% 12-hour PEG prime, mist 90% Control (no prime), every other day 60% 4-hour water prime, every other day 66.67% 12-hour water prime, every other day 76.67% 4-hour PEG prime, every other day 80% 12-hour PEG prime, every other day 60% Control (no prime), every four days 53.33% 4-hour water prime, every four days 36.67% 12-hour water prime, every four days 30% 4-hour PEG prime, every four days 40% 12-hour PEG prime, every four days 26.67%

Sedum spurium Moisture Study 100.00% 90.00% 80.00%

70.00% 60.00% 50.00% 40.00%

Germination (%) Germination 30.00% 20.00% 10.00% 0.00% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Days

Control Mist 4-H2O Mist 12-H2O Mist 4-peg Mist 12-peg Mist Control EOD 4-H2O EOD 12-H2O EOD 4-peg EOD 12-peg EOD Control E4D 4-H2O E4D 12-H2O E4D 4-peg E4D 12-peg E4D

52 Table 4-11. Sedum spurium time to 50% germination of treated and untreated seed in differing levels of moisture. Treatment, Watering Regime Time to 50% Germination (in days) Control (no prime), mist 5.5 4-hour water prime, mist 4.5 12-hour water prime, mist 6.5 4-hour PEG prime, mist 5.5 12-hour PEG prime, mist 5.5 Control (no prime), every other day 6.5 4-hour water prime, every other day 8.5 12-hour water prime, every other day 8.5 4-hour PEG prime, every other day 8.0 12-hour PEG prime, every other day 7.5 Control (no prime), every four days 9.5 4-hour water prime, every four days 10.5 12-hour water prime, every four days 10.5 4-hour PEG prime, every four days 12.5 12-hour PEG prime, every four days 12.5

Conclusion

Given that mist irrigation (watered as frequently as in this study) on a green roof is very rare, the next best treatments were the seeds watered every other day; however, a greenhouse experiment conducted during the spring would likely present significantly different conditions than a green roof during the summer. This study suggested that all of the seed species preferred the moist conditions provided under the mist watering cycle for the first 14 days after sowing and also that watering once every four days was not frequent enough to result in fast and/or high germination rates. Assuming there was no interaction between the Sedum reflexum flats watered every four days and the pad portion of the fan-and-pad greenhouse cooling system, it was also determined that Sedum reflexum seeds may not be as sensitive to lower moisture levels as the other species. Additionally, there was little to no benefit in germination from seed priming treatments in all species when grown under varying moisture conditions.

Chapter 5

Sedum seed installations in 2010 on the Root Cellar roof, and 2011 on the Millennium Building, hydroseeded in modules, and hydroseeded on the Root Cellar roof

Introduction

Currently in the United States several methods are employed for installing plant material on a green roof; one of the greatest advantages or disadvantages of each method is the cost. The most common methods include using cuttings/plugs, nursery containers, vegetative mats, modules, and rarely, seeds. Cuttings/plugs and nursery containers are frequently less expensive methods for installing green roofs; however, they require significant labor for planting.

Vegetative mats can provide an inexpensive method for green roof installation if grown on-site; however, when grown off-site, vegetative mats can be extremely expensive as well as difficult to transport. Modules require a lot of space, and if grown at a nursery facility, they are one of the most expensive methods for installing plant material on a green roof. Seed installations, although quite rare, are one of the most inexpensive methods that can be used for installing a green roof

(Snodgrass, 2006). The cost of labor to install plant material is one of the largest expenses of green roof installations; thus, developing a successful seeding method could substantially reduce the overall price of a green roof.

In the United States, seeds are not a popular method for installing vegetation on green roofs. This is due mainly to the low success rate of the seeds and seedlings, as well as the presumed longer time required for their establishment on the roof. Existing research has shown that seeds can be a successful approach for green roof installations, but only when used for a short period of time in the spring (Snodgrass, 2006). If this successful time period could be extended,

54 possibly through quicker germination and/or less influence of roof conditions on the germination, seeds could become a more viable installation option.

Five seed species (Sedum acre, Sedum forsterianum, Sedum reflexum, Sedum selskianum, and Sedum spurium) were used for this study. Previous research by this author suggested that when seeds were grown under optimum moisture conditions but varying temperatures or optimum temperatures with varying moisture conditions, seed priming for four to twelve hours in polyethylene glycol (PEG) or pure water solutions did not improve germination rates. However, when the seed is exposed to several stressful conditions at one time, such as on a green roof, seed priming may be beneficial to seed germination rates. PEG is one of the most common osmopriming solutions and allows a concentration of low osmotic potential to be created.

Priming seeds in a solution with a low osmotic potential allows the seeds to slowly imbibe the solution, often maintaining the balance of oxygen and water within the seeds better than a standard pure water solution (Ashraf and Foolad, 2005).

Two of the six outdoor trials used hydromulch to keep the seeds near the surface of the medium. The turfgrass industry uses hydromulch to keep grass seed in place, but it can also be used with many other seed species as well. Hydromulch is composed of a slurry of seed and mulch and is spread onto the soil using a hydroseeder machine. It often contains a tackifying agent that adheres the seed and mulch to each other. The process of hydroseeding is a quick and efficient way to apply seed to a large area and to prevent the seed from moving.

Results from previous research by this author indicated that some seed priming treatments produced similar germination rates as those of untreated seeds when subjected to one stressful condition (temperature or moisture levels). The purpose of this study was to apply the author’s previous research on Sedum seed priming to an outdoor green roof study to determine if priming influences seed germination rates under a combination of potentially stressful conditions.

55 Two of the six studies were also performed to determine whether hydroseeding was a viable method for installing seed onto a green roof.

Methods

Roof descriptions

Seed germination studies were performed on outdoor roof trials in the summers of 2010 and 2011. Two of the six sections of the cellar roof located on the Root Cellar behind the Tyson

Building on the Penn State University Park campus were used for the three 2010 seed trials.

Three trials were also conducted in 2011; one was conducted on the Millennium Building of the

Penn State University Park campus; another was conducted in modules using hydroseeding at

Scott’s Landscaping in Centre Hall, Pennsylvania; and the third trial was conducted using hydroseeding on part of one of the two sections of the cellar roof that was also used in 2010.

The Root Cellar is a concrete structure that was built in the 1920s into the side of a hill where one side of the roof is at grade with the top of the slope. The roof is covered with EPDM

(ethylene propylene diene monomer), a polyethylene root barrier, a layer of 9.53 millimeters (3/8 inch) JDrain with root barrier fabric, and topped with green roof media. The medium in the two sections used for this research project were installed at about 10.16 centimeters (four inches) deep. The medium was composed of a sandstone based green roof medium with 9.53 millimeters

(3/8 inch) gravel and compost and was installed in 2007. Plants growing prior to the 2010 study in the two sections used on the cellar roof included mostly Sedum species along with some annuals and perennials. Additionally, some weeds, specifically Portulaca and Cirsium (Thistle) were thriving. Three applications of between five and ten percent Roundup® solutions were sprayed on the two sections of the cellar roof in the spring of 2010. Plants were manually

56 removed several weeks after the Roundup® applications. The 2011 hydroseeding trial on the cellar roof required additional preparation to remove any plants that grew during the second 2010 cellar roof trial. To prevent seed dispersion, flowers were removed from plants in this section during 2010, and any remaining plants were removed prior to the start of the 2011 hydroseeding trial.

The Millennium Building green roof was a Hydrotech green roof, installed in 2010

(Griswold, 2010). The medium was a proprietary blend provided by Hydrotech comprised of a regionally available lightweight aggregate material, a medium to very coarse angular sand, and a mature weed-free compost.

The trial conducted at Scott’s Landscaping in Centre Hall, Pennsylvania, utilized 15 plastic modules that were hydroseeded (Burk, 2010). The plastic modules (measuring 0.61 meters (2 feet) x 1.22 meters (4 feet)) were filled with 10.16 centimeters (four inches) of a medium composed of expanded shale, composted leaf mulch, and perlite.

Species selection

Five seed species were selected for the 2010 and 2011 trials based on whether the seeds exhibited one of the following characteristics in a previous research study: (1) poor germination rates at any temperature, (2) significant decrease in germination rates at one of the sub- or supra- optimal temperatures, or (3) average- or above-average germination rates at all temperatures.

Seed enhancement techniques can alter the optimal temperature of seed germination as well as reduce the amount of time when high levels of moisture are required. Thus, these characteristics led to species selection where either seed germination required a seed enhancement technique to improve germination rates at optimal, sub-, or supra-optimal temperatures or seed germination was average- or above-average at all temperatures (sub-, optimal, and supra-optimal), indicating a

57 potential for success in the extreme climate on a green roof. Additionally, although seeds with average- or above-average germination rates at all temperatures have the potential for success on green roofs without any seed enhancement techniques, such techniques may also improve germination rates and establishment. Previous research by this author indicated that these characteristics provided a potential for higher germination after priming with water or polyethylene glycol (PEG) for 4-12 hours prior to being grown in stressful conditions in a laboratory or greenhouse setting. Good candidates were also readily available and produced drought tolerant plants.

The five selected seed species were:

1. Sedum acre (from Benary Seeds)

2. Sedum forsterianum ‘Oracle’ (from Benary Seeds)

3. Sedum reflexum (from Benary Seeds)

4. Sedum selskianum ‘Spirit’ (from Benary Seeds)

5. Sedum spurium ‘Voodoo’ (from Benary Seeds)

The second and third roof plantings in 2010 also tested a grass seed (Jackson Madnick’s

Pearl’s Premium Ultra Low Maintenance Grass Seed for sunny areas) that was marketed as being very drought tolerant and low-maintenance, and the third planting also seeded in Portulaca. The grass seed was essentially used as a quick study to see how drought tolerant the grass was and became a useful way of determining the distance that different seed treatments may have migrated on the roof surface during rain events. The Portulaca was tested for its effectiveness as a green roof plant in the third trial of 2010 because it continually germinated throughout the hot summer on the cellar roof. Unlike the Sedum seeds (which were supplied by Benary Seed), the

Portulaca seed was hand-collected from the cellar roof in 2010.

58 Design of roof studies – 2010

There are many factors on a roof surface that may create unfavorable conditions for seed germination and establishment. Major issues include the air temperature, the temperature of the medium, moisture content, and seed depth in the medium. Three planting periods were used in the summer of 2010 on the Root Cellar roof, the first plot commenced on July 7, 2010; the second plot commenced on August 1, 2010; and the third plot commenced on September 17, 2010. The medium temperature was typically warmer than the air temperature by an average of eight degrees Celsius (14 degrees Fahrenheit) during the hottest point of the day and three degrees

Celsius (six degrees Fahrenheit) during the coolest point of the day. When supplemental irrigation was required, two oscillating sprinklers were used for about 10 minutes, providing around 10.8 liters of water per square meter (0.26 gallons of water per square foot).

Previous priming experiments by this author on the five selected Sedum species indicated potential for success of priming treatments with water or PEG primed for 4-12 hours. Thus, treated seeds in this study were primed for 4-12 hours either with water or PEG. Seeds were primed in small bundles of material (handkerchiefs). Handkerchiefs were selected because the small size of the five selected seed species required a tightly woven material that was able to withstand long periods of time in the priming solutions without disintegrating. Each handkerchief was cut into four equal sections. Fifty seeds from one seed species were placed on each of these sections. Each section was folded to form a bundle. The bundles were closed with zip-ties. Seed bundles were primed in separate containers of aerated solutions (Table 4-1) to prevent any possible allelopathic effects from one species to another. After removal from the aerated solutions, the bundles were opened and subjected to a standard gravity filtration that allowed the seeds to be removed from the handkerchiefs and collected on filter papers. The seeds were air dried on the filter papers in petri plates (with lids removed) for at least 24 hours.

59 For each seed species, there were five replications of each treatment (three replications of each treatment for the third planting trial). Fifty seeds per treatment were mixed with two tablespoons of sand (to facilitate spreading of the seed) and spread onto their respective roof section for a total of 250 seeds (150 seeds for the third trial) per treatment. Thus, the first and second planting trials consisted of 150 sections, while the third planting trial had 90 sections.

Treatments included (the grass and Portulaca were not primed):

 No seed applied to the plot

 Control (seed applied to the plot but without any seed enhancement techniques)

 4-hour water prime

 12-hour water prime

 4-hour PEG solution prime (at a medium rate intensity of -0.82 MPa)

 12-hour PEG solution prime (at a medium rate intensity of -0.82 MPa)

Design of roof studies – 2011

Three outdoor trials were tested in the summer of 2011, the first trial was conducted on the Millennium Building and commenced on June 10, 2011; the second trial was conducted in modules at a nursery in Centre Hall, Pennsylvania (Scott’s Landscaping), and also commenced on

June 10, 2011; and the third trial was conducted on the Root Cellar roof and commenced on June

20, 2011. The Millennium Building trial was seeded on top of the existing roof medium without hydromulch, while the modules and cellar roof trials were hydroseeded. Mixing the seed treatments in the hydroseeder (Finn Model T30 or Finn Model T90) would have been impossible because of the number of different seed treatments and the small grid sizes; therefore, a thin layer of hydromulch (Profile® 100% wood fiber) was spread on the surface of the medium, then the seeds were spread on the surface of the hydromulch, and finally another layer of hydromulch was

60 sprayed on top of the seed. This allowed for encapsulating the seed in the hydromulch as would be the case if the seed were mixed with the hydromulch in the sprayer. Irrigation on the

Millennium Building was supplied for 30 minutes every six hours using mist irrigation heads.

Irrigation on the hydroseeded module and cellar roof trials was supplied once in the morning for

30 minutes using misting head sprinklers.

A data logger planted in the cellar roof provided media temperatures for the duration of the studies. The temperature of the medium on the cellar roof was typically warmer than the air temperature by an average of 8.33 degrees Celsius (15 degrees Fahrenheit) during the hottest point of the day, and three degrees Celsius (six degrees Fahrenheit) during the coolest point of the day.

The Millennium Building trial consisted of 81 plots, with three replications of each treatment. Seeds were spread in a six inch gridded section between the established rows of plants. Each treatment consisted of 50 seeds. The module trial had 90 sections in 15 modules

(six treatments per module). Each treatment consisted of 50 seeds with three replications per treatment. The cellar roof trial had 150 plots with five replications of 50 seeds per treatment.

Since Sedums are the main plant used on green roofs today, the 2011 summer experiments focused on the same five Sedum species (Sedum acre, Sedum forsterianum, Sedum reflexum, Sedum selskianum, and Sedum spurium). All treated seeds were primed in the same manner as those for the 2010 trials. For each of the studies, the following were used:

 No seed applied to the plot

 Control (seed applied to the plot but without any seed enhancement techniques)

 4-hour water prime

 12-hour water prime

 4-hour PEG solution prime (at a medium rate intensity of -0.82 MPa)

 12-hour PEG solution prime (at a medium rate intensity of -0.82 MPa)

61 Experimental design, data collection, and statistical analysis

The treatments in each of the studies were set up in a completely randomized design.

Seeds were considered germinated when the radicle or leaves were visible on the surface of the medium. When possible, data were analyzed for each species within each study as a regression analysis and an ANOVA using SAS.

It was nearly impossible to take any data throughout 2010 because even when the seeds germinated, the seedlings remained small. With the small seedlings, it was difficult to distinguish any Sedum species or weeds apart. Data were taken in the fall on October 14, 2010; however, statistical analysis was not run on this data as it was still difficult to tell the seedlings apart and the intense summer rain storms resulted in many of the seeds moving out of their respective grids.

Data were collected on the first and third 2010 studies one time in 2011, on July 12.

While plastic modules were used in one of the trials in 2011, each module was simply used as a device to distinguish between each treatment and species and thus is not considered a statistical design influence.

62 Results and Discussion

2010 Root Cellar roof trial results

Results of first Root Cellar roof planting

The week following the first planting (July 7, 2010), the air temperature ranged from 14.4 to 34.4°C (58-94°F) while the media temperature ranged from 16.7 to 43.9°C (62-111°F). There were 6.91 centimeters (2.72 inches) of precipitation throughout the week, so supplemental irrigation was not applied. However, 5.38 centimeters (2.12 inches) of rain fell in several hours during one day, possibly dispersing the seeds around the roof. This first planting was watered with supplemental irrigation every other day for the first four weeks when there was no rainfall.

Without being able to distinguish the difference between weeds, Sedum species from an established seed bank on the roof, and the newly planted Sedum species, no data from 2010 were analyzed. Data from July 2011 showed excellent coverage on the first section planted; however, the majority of the coverage was Sedum album. Sedum album was previously growing on the roof but was not replanted during this study. Therefore, the coverage was likely from an established seed bank in the roof or sprouts from remaining roots of Sedum album.

There were small patches of other Sedum species growing on the roof in July 2011, but it was impossible to determine the treatment from which they grew and there was such a small number of Sedum species, other than Sedum album, that discussion was not warranted.

63 Results of second Root Cellar roof planting

The week following the second planting (August 1, 2010), the air temperature ranged from 13.9 to 32.2°C (57-90°F) while the media temperature ranged from 17.8 to 42.8°C

(64-109°F). Only 1.02 centimeters (0.4 inches) of precipitation fell that week, so supplemental irrigation was provided, again every other day for four weeks when no rainfall occurred.

The second cellar roof planting had the same issues as the first planting with seedlings being unidentifiable in 2010. Data were taken through May 2011 but the only visible plants were

Portulaca, which were not planted. The remainder of the second planting was bare with no

Sedum growth. It is possible that the seeds required a more frequent watering cycle than every other day or the seeds may have started to germinate but died because the young seedlings were unable to withstand the harsh conditions.

Results of third Root Cellar roof planting

The week following the final planting for 2010 (September 17), the air temperature ranged from 7.2 to 31.1°C (45-88°F) while the media temperature ranged from 8.3 to 33.9°C

(47-93°F). There were only trace amounts of rain on several days so supplemental irrigation was provided, this time once every day for the first four weeks. However, there was a powerful rain storm that provided 8.15 centimeters (3.21 inches) of rain less than two weeks after planting.

There was significant germination during the third planting; however, the substantial amount of rain of 8.15 centimeters (3.21 inches) less than two weeks after the planting potentially moved the seed throughout the roof. As of mid-October 2010, the seedlings were too small to identify and thus, data were taken only in the form of observations. Trends showed that the seeds were grouped at the top or bottom of slopes throughout the roof and were especially dense in

64 areas that had visually high levels of organic matter near the surface of the medium. Both of these trends could have occurred due to the 8.15 centimeters (3.21 inches) of rainfall, possibly creating standing water on the roof as the rain water could not percolate through the roof fast enough. The seeds may have floated in the standing water and as it receded some seeds were left on the higher areas of the medium while the rest of the seeds continued to flow to the lowest sections of the medium. Additionally, seeds may have been moved around the surface of the medium if hit by a rain or irrigation droplet. The grass seed was the easiest way to evaluate how far the seeds may have moved. The data recorded on October 14, 2010 showed clumps of grass growing as far away as two to three grids (up to 1.22 meters (four feet)) from where it had been originally planted.

Data were taken on July 12, 2011, to determine whether any analysis on growth could be performed. The seedlings were identifiable as to which species they belonged; however, it cannot be conclusively stated from which treatment the seeds grew. As with the first outdoor study, significant growth was seen in Sedum album and Portulaca and this may have contributed to the poor growth of the planted Sedum seeds as increased competition may have occurred on the roof.

The sections that were not planted with seeds were also covered by both Sedum album and

Portulaca seedlings; these seedlings were likely from an established seed bank in the media prior to this study. The sections where Portulaca seeds were intentionally planted did not result in more seedlings than those sections where Portulaca was not planted.

In July 2011, Sedum acre seedlings seemed to be thriving in all treatments. Specific germination numbers were impossible to record as Sedum acre spreads very quickly; therefore, the overall establishment was evaluated rather than germination percentages. There were large clumps of Sedum acre growing in all treatments yet not one specific treatment appeared to have improved growth. Sedum acre germinated and spread the quickest providing a solid mass of plants when compared with the other four species tested. Sedum forsterianum also had spreading

65 growth in all treatments but with low coverage rates. Sedum reflexum had spreading growth in the 4-hour PEG prime, 12-hour water prime, and 12-hour PEG prime treatments with the highest establishment rates in the 4-hour PEG prime treatments. Sedum selskianum had a small, but relatively equal amount of plants growing in the majority of the treatments and did not yield as much coverage as some of the other species. Sedum spurium had some seed germination in all treatments but at relatively low numbers and did not appear to spread. The highest germination rates for Sedum spurium were seen in the control (no-prime) treatments and in the 12-hour PEG prime treatments.

Although establishment observations were taken, due to obvious seed movement (as shown through the grass seed data from 2010), it is impossible to confidently state that the aforementioned treatment results are accurate for each species.

2011 Millennium Building trial, module trial, and Root Cellar roof trial results

Millennium Building trial – 2011

The week following the Millennium Building planting (June 10, 2011), the air temperature ranged from 7.2 to 28.3°C (45-83°F) while the media temperature ranged from 35.6 to 50°C (96-122°F) on the Root Cellar roof. Temperature data were used from the Root Cellar roof as it had a similar orientation as the Millennium Building and was located nearby (less than a quarter mile away). There were 6.4 centimeters (2.52 inches) of precipitation throughout the week, in addition to the amount added through supplemental irrigation supplied for 30 minutes every six hours. However, 4.14 centimeters (1.63 inches) of rain fell in several hours immediately following the planting.

66 Seed on the Millennium Building reacted in a similar fashion to the seed in the outdoor trials performed in 2010 in that the seed moved around the roof. Even though these seeds did not move as much as those on the cellar roof in 2010, some seed movement was visible. Within 24 hours of the seeds being spread onto the roof, over 3.81 centimeters (1.5 inches) of rain fell. Seed germination did not begin to occur for another two weeks, possibly due to the extremely wet conditions. It is possible that the Sedum seeds remained in a quiescent state until the moisture levels in the medium decreased, but with consistent irrigation every six hours and the rain events, that would have taken several days to occur. Multiple regression analyses of the data for each of the five species from weeks three, four, and five of the study showed that the proportion of germinated seeds was not related to the PEG concentration, the duration of the priming period, or the interaction between the PEG concentration and the priming period. Each treatment in Sedum acre had germination percentages below 56%. Sedum forsterianum germination was below 35%, and Sedum reflexum germination averaged 50%. Sedum selskianum germination was below 50%, and Sedum spurium germination was below 35%.

By the end of July (48 days into the study), irrigation was removed from the roof.

Almost every seedling was dead at this point, most likely due to the combination of rain, irrigation, and heat. Although there was some early success with this study, in the end, it resulted in the same conclusions as in the 2010 cellar roof studies – a green roof without something to bind the seed will not succeed in the long term. Additionally, there may be a maximum amount of moisture or high temperatures that Sedum seedlings can tolerate.

Module trial

The week following the module planting (June 10, 2011), the air temperature ranged from 7.2 to 28.3°C (45-83°F) while the media temperature ranged from 35.6 to 50°C (96-122°F).

67 There were 6.4 centimeters (2.52 inches) of precipitation throughout the week, in addition to the amount added through supplemental irrigation supplied for 30 minutes once a day. However,

4.14 centimeters (1.63 inches) of rain fell in several hours immediately following both plantings.

Although 4.14 centimeters (1.63 inches) of rain fell in several hours immediately following the module hydroseeding, unlike the studies without hydromulch, the seeds in the module study remained in place after this rain event. Data were taken for the module study on days 3, 7, 10, 14, 21, 26, and 32.

Sedum acre germination on day 21 was influenced by the interaction of the PEG concentration and the duration of the priming time (Figure 5-1). The multiple regression analysis run on the data resulted in a significant interaction with 56.19% of the variation explained in the model (p-value of 0.0055). Seeds that were primed in PEG for four hours and seeds that were primed in pure water for 12 hours had the highest germination percentages, both around 55%.

However, by day 26, germination was not related to treatment. Table 5-1 shows the final germination (on day 32) for Sedum acre, which ranged from 42% (control) to 72% (12-hour water prime).

Sedum acre Germination 60.0%

50.0%

40.0%

30.0%

Germination (%) Germination 20.0%

10.0%

0.0% 0 4 8 12 Duration of Priming (in hours)

Water -0.82 MPa PEG

Figure 5-1. Interaction between length of priming and priming solution for Sedum acre germination on day 21.

Multiple regression analyses for both Sedum forsterianum and Sedum selskianum indicated that the proportion of germinated seeds was not related to the PEG concentration, the duration of the priming period, or the interaction between the PEG concentration and the length of the priming period on any day. Sedum forsterianum had very low germination throughout the study, ending with rates under 16% (Table 5-1). Final germination percentages for Sedum selskianum ranged between 42.7% and 50% (Table 5-1).

Data for Sedum reflexum germination on day 26 indicated a significant difference between means with PEG concentration (r-squared = 0.4973, p-value = 0.0024). All germination was below 50% and seeds with no PEG treatment (including no-prime, 4-hour water prime, and

12-hour water prime) had significantly higher germination than those seeds with a PEG treatment

69 (Figure 5-2). By day 32, the difference between seeds with a PEG treatment and without a PEG treatment was not significant. Final germination percentages for Sedum reflexum ranged between

31.3% and 49% (Table 5-1).

Sedum reflexum Germination 60.0%

50.0%

40.0%

30.0%

20.0% Germination (%) Germination

10.0%

0.0% 0 -0.82 PEG Concentration (in MPa)

Figure 5-2. Seed germination for Sedum reflexum based on the priming solution on day 26 (n=3).

Treatments of Sedum spurium showed significant germination regression trends on days

21 and 32. On day 21, multiple regression analysis revealed a significant trend between the interaction of the PEG concentration and the length of the priming time (r-squared = 0.57, p-value = 0.0164). Seeds primed for 12 hours in water had the highest germination; although, the germination percentage for the 12-hour water prime treatment was only 27% (Figure 5-3). On day 32, the multiple regression analysis only showed a significant trend between priming times and germination (r-squared = 0.4145, p-value = 0.013). Seeds primed for 12 hours showed significantly higher germination than those seeds with no-prime or a 4-hour prime (Figure 5-4).

Seeds primed for 12 hours had an average germination of 35.7%, while seeds primed for four

70 hours averaged 27.7%, and seeds with no-prime averaged 18.7%. At the end of this study, Sedum spurium germination percentages ranged between 18.7% and 38.7%.

Sedum spurium Germination 30.0%

25.0%

20.0%

15.0%

Germination (%) Germination 10.0%

5.0%

0.0% 0 4 8 12 Length of Priming (in hours)

Water -0.82 MPa PEG

Figure 5-3. Interaction between length of priming time and priming solution for Sedum spurium germination on day 21.

Sedum spurium Germination 45.0% 40.0%

35.0%

30.0% 25.0% 20.0%

Germination (%) Germination 15.0% 10.0% 5.0% 0.0% 0 2 4 6 8 10 12 14 Length of Priming (in hours)

Germination Predicted (Linear)

Figure 5-4. Seed germination percentages in relation to the length of priming for Sedum spurium on day 32.

Table 5-1. Final germination of treated and untreated seed in the module study after one month (day 32). 4-hour 12-hour 4-hour 12-hour Plant Species Control Water Prime Water Prime PEG Prime PEG Prime Sedum acre 42.0% 59.3% 72.0% 62.0% 46.0% Sedum forsterianum 12.0% 1.3% 2.0% 16.0% 8.7% Sedum reflexum 36.0% 42.0% 49.0% 34.0% 31.3% Sedum selskianum 42.7% 50.0% 44.0% 50.0% 44.7% Sedum spurium 18.7% 24.7% 38.7% 30.7% 32.7%

72 Root Cellar roof trial

The week following the hydroseeding of the cellar roof (June 20, 2011), the air temperature ranged from 11.7 to 28.9°C (53-84°F) while the media temperature ranged from

23.9 to 52.2°C (75-126°F). There were 2.29 centimeters (0.9 inches) of precipitation throughout the week, in addition to the supplemental irrigation supplied for 30 minutes once a day.

Data were taken on days 8, 12, 34, and 63 for the hydroseeded cellar roof trial. Multiple regression analyses for Sedum acre, Sedum reflexum, and Sedum spurium indicated that the proportion of germinated seeds was not related to the PEG concentration, the priming period, or the interaction between the PEG concentration and the priming period on any days.

Multiple regression analysis on each day of Sedum forsterianum data suggested that only the PEG treatment and germination was significant and only for day 34. All other analyses illustrated that the proportion of germinated seeds was not influenced by other treatments on any other days of data collection. On day 34, the multiple regression showed a significant trend in the priming solution containing the PEG concentration (r-squared = 0.2549, p-value = 0.01), with the seeds primed in PEG having higher germination than those primed in water. However, the mean germination for Sedum forsterianum seeds primed in PEG was only 1.4% (only seven out of 500 seeds) while only one seed (out of 500) germinated from the seeds primed with only water.

Although multiple regression analysis run on the data showed a significant difference between

PEG treatment and germination, with rates below 2%, this would not be considered a successful treatment for practical uses.

Sedum selskianum data analysis resulted in a significant difference in germination with priming times on day 12; although, multiple regression on the data showed there were no significant differences for any other treatment on any other day of data collection. Similar to the

Sedum forsterianum results, although significant, with an r-squared value of 0.3573 and a p-value

73 of 0.0016, germination percentages were all below 5%, so no treatment would be considered successful.

Similar to the module study, this study was a success from the standpoint that the hydromulch held the seed in place near the surface of the medium. However, final germination results one month and two months after hydroseeding showed that the priming treatments, with water or PEG, did not significantly improve germination. Additionally, all germination percentages were below 31% (Tables 5-2 and 5-3). Although more seed could be applied to counteract the low germination, more studies should be performed to reduce variability in the statistical analysis. Of the five species, Sedum forsterianum and Sedum spurium had the lowest germination, below 8% for any treatment after one month of observation, so based solely on the cellar roof study, they would not be recommended for a hydroseeding application.

Table 5-2. Final germination of treated and untreated seed in the Root Cellar roof hydromulch study after one month (day 34). 4-hour 12-hour 4-hour 12-hour Plant Species Control Water Prime Water Prime PEG Prime PEG Prime Sedum acre 15.6% 22.0% 30.8% 21.6% 20.4% Sedum forsterianum 0.0% 0.4% 0.0% 2.0% 0.8% Sedum reflexum 13.2% 14.0% 14.4% 8.4% 18.0% Sedum selskianum 19.2% 25.6% 27.2% 21.6% 24.8% Sedum spurium 4.8% 3.6% 6.8% 4.4% 7.6%

Table 5-3. Final germination of treated and untreated seed in the Root Cellar roof hydromulch study after two months (day 63). 4-hour Water 12-hour 4-hour 12-hour Plant Species Control Prime Water Prime PEG Prime PEG Prime Sedum acre 12.4% 19.6% 20.4% 13.2% 16.4% Sedum forsterianum 0.0% 0.8% 0.0% 0.8% 0.4% Sedum reflexum 13.6% 20.0% 13.2% 12.4% 17.6% Sedum selskianum 20.0% 26.0% 28.4% 24.8% 28.8% Sedum spurium 4.0% 5.2% 6.0% 4.0% 4.4%

74 Conclusion

In general, the third outdoor cellar roof planting in 2010 performed better than the first two trials as both germination and establishment occurred, but data were still inconclusive.

Sedum acre seeds germinated and spread the most during the ten months from initial planting, but seed movement rendered it impossible to determine whether one treatment was more successful than another. In general, these experiments demonstrated that seed germination on a green roof requires a stabilizing mechanism to help bind the seed to the surface of the media to prevent seed movement so establishment can occur.

Although final germination percentages for all species except Sedum acre in both the

2011 module and 2011 Root Cellar roof trials were below 50%, this was a success over the studies performed without hydromulch. The hydromulch succeeded in keeping the seeds in place near the surface of the medium. Seed company trials (performed by Benary Seed) for the Sedum seeds used in this study suggested a viability of around 85%. Due to the small size of the Sedum seeds, it is likely some seed was lost throughout the priming and/or sowing process. One solution to overcome the low germination rates in outdoor trials would be to increase the number of seeds applied. Results from both the module and cellar roof trials in 2011 showed that the control

(no-prime) seeds had statistically similar germination numbers as the treated seeds after one month of observation in Sedum acre, Sedum reflexum, and Sedum selskianum. Since Sedum forsterianum seed germination resulted in a significant regression analysis, with germination percentages below 2%, this would not be considered a successful trial for practical uses. The additional cost, labor, and time to prime the seeds would not be recommended for Sedum acre,

Sedum forsterianum, Sedum reflexum, or Sedum selskianum. Sedum spurium, on the other hand, did show a significant difference in the treated and untreated seeds after one month in the module trial, although seed germination was at low percentages. The 12-hour primes (either with water

75 or PEG), had the highest germination with an average of 35.7%. Meanwhile, the 4-hour primes

(either with water or PEG) resulted in an average of 27.7% germination, and the no-prime control resulted in 18.7% germination. Although statistically significant with an r-squared value of

0.4145, more research is needed to determine whether the improved seed germination through priming is worth the expense for Sedum spurium.

Chapter 6

Seed maturation over time of Sedum species

Introduction

Recommendations for most seed species is to use the seeds as soon as possible after harvesting as seeds may undergo physiological changes when stored at room temperature over time, which produces lower germination results. However, seeds are typically stored for varying amounts of time after harvest and prior to use. Because the rate of physiological change is slowed by cool environments, seeds stored in cool conditions often remain viable for longer periods of time than those stored at room temperature (Baskin and Baskin, 1998). Every seed species has a predetermined lifespan that is based on the storage conditions and rate of deterioration. Seeds are considered either recalcitrant or orthodox depending on their storage requirements. Recalcitrant seeds do not tolerate drying and must be stored so seed moisture levels are at or above 25%. Orthodox seeds, however, can tolerate drying and can be stored in this state for many years. Sedum seeds are orthodox seeds. Orthodox seeds that are stored under low humidity and at low temperatures can often survive for many years; although, it is crucial to perform germination tests throughout any storage period to ensure the seeds are not undergoing rapid physiological changes (Hartmann, et al., 2011).

Germination tests are performed to determine the viability of seeds and are run by simply placing a specified number of seeds in an optimal environment for a specified period of time.

Germination test results are typically recorded in both final germination rates (after a specific amount of time) and the T50, or time to 50% germination (Baskin and Baskin, 1998). Seeds that fail to germinate are considered either dormant or dead (Hartmann, et al., 2011).

77 The purpose of this study was to determine whether seed age affects germination rates of five Sedum species. Currently, there is no published research on whether seed storage affects seed germination rates of Sedum species.

Methods

Design of maturation study

Five Sedum species (Sedum acre, Sedum forsterianum, Sedum reflexum, Sedum selskianum, and Sedum spurium) were received from Benary Seed on December 20, 2010.

Benary reported a germination rate of 85% for each seed species when tested in late spring/early summer of 2010. Therefore the seeds were at least 6-8 months old when received, however exact dates of harvest, packaging, and pre-shipment storage conditions were not available from Benary.

Upon receipt, the seeds were immediately placed in a refrigerator set to around 4.44°C (40°F).

Seeds were stored at this temperature for the duration of the study.

Every six to eight weeks, seeds were tested for viability with optimum temperature conditions in a 21.1°C (70°F) or supra-optimal temperature conditions in a 32.2°C (90°F) growth chamber. One hundred seeds of each species were separated into sets of 25 seeds providing four replications per temperature treatment. Each set of 25 seeds was placed in a petri plate with one piece of filter paper and 1.5 milliliters of water was added. The petri plates were then double wrapped with parafilm and placed in sets of four in ziplock bags.

78 Experimental design, data collection, and statistical analysis

All petri plates in ziplock bags were placed in the growth chambers and were set up in a completely randomized design; the plates were re-randomized every other day. Data were collected using dissecting microscopes each day. Seeds were considered germinated when the radicle was at least one quarter the size of the seed. Using SAS, an ANOVA was run on germination data on day 21 and on the time to 50% germination. A Tukey’s test was used to separate means.

Results and Discussion

Sedum seed maturation tested at 21.1 degree Celsius (70 degree Fahrenheit)

In general, Sedum acre seeds germinated at higher percentages as they aged when grown in a 21.1 degrees Celsius (70 degrees Fahrenheit) growth chamber. The highest germination percentages were observed when the seeds had been stored for between five and 11 months.

After five months of storage, seed germination was above 90%; younger seeds germinated between 60% and 70%, and older seeds germinated between 70% and 90% (Figure 6-1).

Additionally, after five months of storage, Sedum acre seeds germinated at a faster rate than younger and older seeds. Seed germination reached 50% of the final germination within an average of 1.5 days, at least twice as fast as seed at any other age. Time to reach 50% germination at other ages varied between an average of 3.5 days and 6.5 days. Seeds stored for

6.5 months, 8.5 months, and 11 months reached final germination percentages similar to the seed stored for five months; however, it took significantly longer for those seeds to reach the final germination (Figure 6-2). Thus, the Sedum acre seed stored for five months were the best option for achieving high germination in the shortest amount of time.

Sedum acre Germination 100% 90% 80%

70% 60% 50% 40%

Germination (%) Germination 30% 20% 10% 0% 1.5 3 5 6.5 8.5 11 Seed Age (in months)

Figure 6-1. Germination percentages for Sedum acre seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4).

Sedum acre T50

8.0

7.0

6.0

5.0

4.0

3.0

2.0

1.0 Time to 50% Germination (in days) (in Germination 50% to Time 0.0 1.5 3 5 6.5 8.5 11 Seed Age (in months)

Figure 6-2. Time to 50% germination for Sedum acre seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4).

80 Sedum forsterianum seeds had the highest germination percentage when seeds were stored for about five months. After three weeks in the growth chamber, seeds at all ages germinated between 82% and 98% (Figure 6-3). The largest difference in germination occurred when observing data for the time to 50% germination. Seed stored for five months germinated the fastest, taking an average of 2.25 days to reach 50% germination. Younger seeds took between 8.5 and 13.5 days, while older seeds took between 8.0 and 9.5 days to reach 50% germination (Figure 6-4). Therefore, the seed stored for five months would be the best option to reach high germination quickly.

Sedum forsterianum Germination 100% 90% 80%

70% 60% 50% 40%

Germination (%) Germination 30% 20% 10% 0% 1.5 3 5 6.5 8.5 11 Seed Age (in months)

Figure 6-3. Germination percentages for Sedum forsterianum seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4).

Sedum forsterianum T50

16.0

14.0

12.0

10.0

8.0

6.0

4.0

2.0 Time to 50% Germination (in days) (in Germination 50% to Time 0.0 1.5 3 5 6.5 8.5 11 Seed Age (in months)

Figure 6-4. Time to 50% germination for Sedum forsterianum seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4).

There were no significant differences within the final germination percentages for Sedum reflexum on day 21, the final day of data collection. Final germination ranged between 84% and

94%. However, there were significant differences in the time it took to reach 50% germination as younger seeds germinated at the fastest rates. Seeds stored between 1.5 and 6.5 months reached

50% germination within 2.5 to 3.5 days while the oldest seeds (stored for 8.5 and 11 months) required 4.25 days to reach 50% germination (Figure 6-5). Since all final germination percentages were similar, to achieve the quickest and highest germination rates, recommendations would be to use seed stored for less than 6.5 months.

Sedum reflexum T50

5.0

4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0

0.5 Time to 50% Germination (in days) (in Germination 50% to Time 0.0 1.5 3 5 6.5 8.5 11 Seed Age (in months)

Figure 6-5. Time to 50% germination for Sedum reflexum seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4).

Sedum selskianum also did not show significant differences in final germination percentages, which ranged from 88% to 98%, on day 21. Seeds that were stored for five months reached 50% germination the quickest, taking just over two days. Younger seeds took 3.5 and

4.5 days, while older seeds took between 3.5 and 4.0 days to reach 50% germination (Figure 6-6).

Sedum selskianum T50

6.0

5.0

4.0

3.0

2.0

1.0 Time to 50% Germination (in days) (in Germination 50% to Time 0.0 1.5 3 5 6.5 8.5 11 Seed Age (in months)

Figure 6-6. Time to 50% germination for Sedum selskianum seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4).

Sedum spurium seed age had little impact on the final germination percentages. All seeds germinated between 81% and 96% by day 21. The highest final germination percentages were the seeds that were stored between three and 11 months, ranging between 85% and 96% germination. Younger seed (stored for 1.5 months) had a lower final germination of 81%

(Figure 6-7). Data for the time to 50% germination ranged between 3.5 and 6.5 days

(Figure 6-8). The quickest germination occurred in seeds that were stored for 1.5, five, or 6.5 months. It took an average of 3.75 days for seeds stored for 1.5 months, 3.5 days for seeds stored for five months, and 4.5 days for seeds stored for 6.5 months to reach 50% germination. The slowest germinating seeds were the oldest seeds taking six days to reach 50% germination when seeds were stored for 8.5 months, and 6.5 days for seeds that were stored for 11 months. As all

Sedum spurium seeds had high germination percentages, the best seed for fast and high germination rates would the younger seed (stored for less than 6.5 months).

Sedum spurium Germination 100% 90% 80%

70% 60% 50% 40%

Germination (%) Germination 30% 20% 10% 0% 1.5 3 5 6.5 8.5 11 Seed Age (in months)

Figure 6-7. Germination percentages for Sedum spurium seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4).

Sedum spurium T50

8.0

7.0

6.0

5.0

4.0

3.0

2.0

1.0 Time to 50% Germination (in days) (in Germination 50% to Time 0.0 1.5 3 5 6.5 8.5 11 Seed Age (in months)

Figure 6-8. Time to 50% germination for Sedum spurium seeds after different lengths of storage in a 21.1°C (70°F) growth chamber (n=4).

85 Sedum seed maturation tested at 32.2 degree Celsius (90 degree Fahrenheit)

Sedum acre germination percentages decreased as the seeds matured when placed in a

32.2 degree Celsius (90 degree Fahrenheit) growth chamber. Final seed germination started just below 60% when seeds were stored for 1.5 months and ended with an average of 18% germination for seeds stored between 6.5 and nine months (Figure 6-9). However, seed germination was quicker in seeds stored for between five and 6.5 months as they reached 50% germination in less than three days. Meanwhile, both the younger seeds that were tested (stored for 1.5 and three months) and the oldest seeds (stored for nine months) took over four days to reach 50% germination (Figure 6-10). Although seeds stored for five and 6.5 months had the quickest time to 50% germination, since their final germinations were each less than 50% of the youngest seeds (stored for 1.5 months), young Sedum acre seeds would be recommended for use in warmer temperatures.

Sedum acre Germination 100% 90% 80%

70% 60% 50% 40%

Germination (%) Germination 30% 20% 10% 0% 1.5 3 5 6.5 9 Seed Age (in months)

Figure 6-9. Germination percentages for Sedum acre seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4).

Sedum acre T50

7.0

6.0

5.0

4.0

3.0

2.0

1.0

TIme to 50% Germination (in days) (in Germination 50% to TIme 0.0 1.5 3 5 6.5 9 Seed Age (in months)

Figure 6-10. Time to 50% germination for Sedum acre seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4).

Sedum forsterianum seeds also had decreased germination as seed aged when germinated in 32.2 degree Celsius (90 degree Fahrenheit) growth chambers. However, in general, germination was below 10% at all seed ages and thus, would not provide sufficient germination at high temperatures without a seed treatment or other seed enhancement technique (Figure 6-11).

Previous studies by this author suggested that seed priming treatments also did not significantly improve germination rates on a green roof. As a result, a reasonable recommendation would be to forgo the use Sedum forsterianum seeds on a green roof.

Sedum forsterianum Germination 100% 90% 80%

70% 60% 50% 40%

Germination (%) Germination 30% 20% 10% 0% 1.5 3 5 6.5 9 Seed Age (in months)

Figure 6-11. Germination percentages for Sedum forsterianum seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4).

Sedum reflexum seeds had a significant decrease in germination as seed aged. Young seeds (stored for 1.5 months) germinated around 40% in 32.2 degree Celsius (90 degree

Fahrenheit) temperatures. Seeds stored for three months and five months had similar germination percentages to each other, both under 10%. Seeds stored for six months and longer did not germinate in the 32.2 degree Celsius (90 degree Fahrenheit) temperature (Figure 6-12).

Statistically, seeds stored for 1.5 months, three months, and five months all reached 50% germination at similar times (Figure 6-13) but as the youngest seeds produced the highest germination percentages, it was found to be more beneficial as it produces the best combination of the highest and fastest germination rates.

Sedum reflexum Germination 50% 45% 40%

35% 30% 25% 20%

Germination (%) Germination 15% 10% 5% 0% 1.5 3 5 6.5 9 Seed Age (in months)

Figure 6-12. Germination percentages for Sedum reflexum seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4).

Sedum reflexum T50

14.0

12.0

10.0

8.0

6.0

4.0

2.0 Time to 50% Germination (in days)(in Germination 50% to Time 0.0 1.5 3 5 6.5 9 Seed Age (in months)

Figure 6-13. Time to 50% germination for Sedum reflexum seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4).

89 Significant differences were observed in final seed germination percentages for Sedum selskianum on day 21. Although the data for Sedum selskianum on day 21 show similar final germination percentages in all age groups except the seeds stored for 6.5 months, it is likely this was due to random variation and seed age may not have directly affected seed germination.

Additionally, all seed germination percentages were relatively high, ranging from 83 to 94%

(Figure 6-14). Time to 50% germination ranged between just under three days to just over four days (Figure 6-15). Seeds stored for longer than five months produced the quickest germination rates.

Sedum selskianum Germination 100% 90% 80%

70% 60% 50% 40%

Germination (%) Germination 30% 20% 10% 0% 1.5 3 5 6.5 9 Seed Age (in months)

Figure 6-14. Germination percentages for Sedum selskianum seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4).

Sedum selskianum T50 5.0

4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5

Time to 50% Germination (in days)(in Germination 50% to Time 0.0 1.5 3 5 6.5 9 Seed Age (in months)

Figure 6-15. Time to 50% germination for Sedum selskianum seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4).

The youngest (stored for 1.5 months) Sedum spurium seeds had the highest germination percentages at the supra-optimal temperature; seeds germinated around 75% when stored for

1.5 months. Germination decreased over time (down to 25% germination after seed was stored for 6.5 months) until time of seed storage was nine months. At that point, seed germination percentages increased to around 50% germination (Figure 6-16). It is possible there was a secondary dormancy in Sedum spurium that caused the decrease and then increase in germination.

There was no significant difference in the time it took for seeds to reach 50% germination. Thus, results of this study suggest use of young seeds as they had the best final germination percentages. More studies on how Sedum spurium seed ages after being stored for nine months would be useful to determine if a secondary dormancy exists and causes the increase in germination rates after seed has been stored for nine months.

Sedum spurium Germination 90% 80%

70%

60% 50% 40%

30% Germination (%) Germination 20% 10% 0% 1.5 3 5 6.5 9 Seed Age (in months)

Figure 6-16. Germination percentages for Sedum spurium seeds after different lengths of storage in a 32.2°C (90°F) growth chamber (n=4).

Conclusion

In general, the younger seeds produced faster and higher germination rates in both the

21.1°C (70°F) and 32.2°C (90°F) temperatures for Sedum acre and Sedum reflexum. Sedum spurium seeds had the fastest and highest germination rates when stored for between three and five months. Sedum forsterianum seeds were very sensitive to increased temperature and thus, would be unlikely to produce adequate coverage on a green roof at any seed age unless the temperatures did not fluctuate from around 21.1°C (70°F). Sedum selskianum was the only one of the five species tested where germination rate was unaffected by seed age at high temperature.

Chapter 7

Conclusion

Seed Installation for a Green Roof

Seed germination rates throughout the outdoor trials in 2010 and on the Millennium

Building in 2011 demonstrated that successful seed germination on a green roof is unlikely to occur without some treatment that holds the seeds in place near the surface of the roof. The hydromulch appeared to work well in 2011; although, the Root Cellar roof germination results were significantly lower than the module study results. The cellar roof hydroseeded germination results were an average of 3.3 times lower than the module study results. Given that seed germination was almost non-existent on that same section of the cellar roof in 2010, it is possible that the medium in that section of the roof was altered over time and was significantly different than the other section of the cellar roof used in 2010 and the medium used in the 2011 module trial, resulting in the lower germination rates.

Additionally, outdoor seed germination rates were typically lower than laboratory germination rates. Seeds in the laboratory were provided with a constant temperature and adequate moisture at all times. Furthermore, seeds in petri plates had no other plant competition nor were they going to disappear by movement through the medium or by insects or any other conditions that could be detrimental to their health when planted on an outdoor green roof.

Sedum acre seeds in both laboratory and outdoor studies germinated just as well, if not better in the control treatments than the primed treatments. In the laboratory studies, there was a significant decrease in germination from the control to the 12-hour water primed seeds when germinated at an optimal temperature. The control seeds germinated at 100% while the 12-hour

93 water primed seeds germinated at 48%. However, when the control and the 12-hour water primed seeds were germinated in an extreme temperature of 32.2°C (90°F), there was no significant difference between their germination percentages as the control germinated at 86% and the 12-hour water prime germinated at 79%. Additionally, no other priming treatment (lower priming time period and/or the inclusion of various concentrations of PEG) significantly improved germination. Thus, for Sedum acre, the additional time and labor costs for priming seed would be insignificant in extreme temperatures.

The outdoor hydromulch trials also showed no significant improvement in germination rates of treated Sedum acre seeds and control seeds. However, after one month, the control seeds in the module study germinated at 42%, while the 12-hour water primed seeds germinated at

72%. The control seeds in the cellar roof hydromulch study germinated at 15.6%, while the

12-hour water primed seeds germinated at 30.8% after one month. The control seeds (average of the two hydroseeded studies was 28.8%) germinated about 50% lower than the 12-hour water primed seeds (average of the two hydroseeded studies was 51.4%), but because there was a large amount of variation within treatments, statistical analysis resulted in no significant differences.

As seed companies do not currently sell primed Sedum acre seeds, and taking into account the laboratory studies and outdoor hydromulch trials, recommendations for a successful

Sedum acre seed establishment on a green roof would be to hydrospray unprimed seed. The additional amount of time and labor to prep, prime, and re-dry the seeds would likely surpass the cost of buying additional untreated seed. By simply doubling or tripling the number of untreated

Sedum acre seeds, practical germination rates might be achieved. Additionally, Sedum acre seedlings are very quick to spread and establish masses of seedlings.

Sedum forsterianum was not tested in the initial seed priming studies due to lack of seed.

It was assumed that Sedum forsterianum seeds may react in similar ways to the other four Sedum species; thus, the same treatments were applied to the Sedum forsterianum seed for outdoor

94 studies as the other four species. In general, Sedum forsterianum seeds had very low germination percentages. On the Millennium Building study, results for all treatments were below 35% and after three weeks, all seedlings had died. In both of the hydromulch studies, Sedum forsterianum germination rates were again low, below 16%. Sedum forsterianum is not an ideal candidate for seed installation on a green roof because of low germination rates in higher temperatures. If, however, future seed enhancement research improves germination in high temperatures, Sedum forsterianum may become a viable candidate.

Seed germination rates for Sedum reflexum in the laboratory settings showed there was a quadratic relationship between the control and 12-48 hour water primes. All seed treatments germinated at or above 78%. Specifically, seeds primed for 36 hours or less (including the control) germinated at 90% or higher. When primed in water or PEG for 4-12 hours and grown in a 32.2°C (90°F) growth chamber, there were no significant differences between treatments.

Outdoor studies also showed no significant differences between treatments after one month.

Given there were no significant differences between treatments, and germination rates were similar between treated and untreated seeds, recommendations for use of Sedum reflexum seeds for a hydrosprayed green roof would be similar to Sedum acre in that the untreated seed would be just as successful. Outdoor germination rates on the hydroseeded trials for untreated Sedum reflexum seed averaged 24.6%; therefore, additional numbers of untreated seed should be applied for full coverage.

Sedum selskianum had similar germination rates between treatments in each study, both in the laboratory and outdoors. In the first priming study in which seeds were primed in water solutions for 12-48 hours, there was a negative linear relationship between untreated seeds and seeds primed for 12-48 hours with the untreated, control seeds resulting in the highest germination. When seeds were primed for 4-12 hours with water or PEG, the higher concentration of PEG produced significantly higher germination rates when grown in a

95 32.2°C (90°F) growth chamber, although all germination percentages were above 92%. The high germination of all treatments, including the control, brings into question whether the additional cost of treatments is worth the small additional percentages in germination. In the outdoor hydroseeded trials, priming treatments did not result in higher germination rates (statistically or observationally); thus, it would be recommended to use untreated Sedum selskianum seed for a green roof. Averaging the two hydroseeded studies, the untreated, hydrosprayed Sedum selskianum seeds had an average germination of 31%. Once again, additional seed should be applied to account for the lower germination.

In both laboratory priming studies, the untreated control Sedum spurium seed resulted in significantly higher germination rates than primed seeds. The outdoor module study contradicted the laboratory data as there was a linear regression between priming time and germination. The

12-hour primes, followed by the 4-hour primes, produced significantly higher germination than the control. However, the Sedum spurium seeds hydrosprayed onto the cellar roof produced yet another set of results. Data from seed germination from the trial on the cellar roof showed no significant differences between the duration of priming, PEG concentration, or the interaction of the two. It should be noted that all Sedum spurium germination percentages on the cellar roof were below 8%, which brought the average untreated, hydroseeded Sedum spurium seed germination rate to 11.8%. It is difficult to make a recommendation on the best Sedum spurium treatment without more data. Nevertheless, as laboratory studies in both optimal and supra- optimal conditions resulted in the control producing higher germination and one of the hydroseeded studies resulting in no statistical differences, it is likely that use of untreated Sedum spurium seeds could produce a successful green roof.

In order to create a dense mat of Sedum species on a green roof, an ideal situation would be a minimum of one germinated seedling per square inch. This would amount to 72 seedlings per square foot. In order to determine how many seeds to apply for each species to achieve the

96 desired 72 seedlings per square foot, that total (72) must be divided by the percent germination from the outdoor hydroseeded studies. The average germination for the untreated, control seeds from the 2011 cellar roof trial and the module trial were used to estimate the number of total seeds required (Table 7-1). The recommended numbers of seeds are only for each species, not a mixture of seed species. In creating a seed mixture of the four Sedum species, lower amounts of

Sedum acre seed should be used as it spreads very quickly once it has germinated, and this could cause competition between the other species. As there are significant variations between seed companies in the number of estimated seeds in a gram, once a supplier is determined, simple calculations can be performed to establish the total weight of seed required.

Table 7-1. Calculations for the recommended number of seeds per square foot for suggested seed species. Desired Number of Germination Number of number of seedlings per Cost per gram Seed species rate of seeds required seedlings gram (Jelitto, 2012) untreated seed (per sq ft) (per sq ft) (Jelitto, 2012) Sedum acre 72 28.8% 500 seeds 4,000 $7.21 Sedum reflexum 72 24.6% 585 seeds 2,000 $7.21 Sedum selskianum 72 31.0% 465 seeds 4,000 $10.67 Sedum spurium 72 11.8% 1,220 seeds 4,000 $130.77

Utilizing a hydroseeding application for installing plant material on a green roof can drastically reduce the cost. According to Scott Burk of Scott’s Landscaping in Centre Hall,

Pennsylvania (2010), there is a significant difference in the labor costs for installing a green roof through the use of plugs or seeds. For example, it is assumed that one laborer can plant 50 plugs per hour or seed a 2,500 square foot area in one hour using a hydroseeder. Using either method, the labor costs for Scott Burk are $50.00 per hour. Therefore, just the labor costs for a 40,000 square foot roof, using two plugs per square foot, would cost around $80,000 to plant plugs on the green roof. However, to hydroseed a 40,000 square foot roof, labor costs would only be $800.

97 Seed Maturation

This study examined the influence seed age has on germination rates when seeds were stored in a dry, cool setting. In the optimal germination temperature, 21.1°C (70°F), Sedum acre seeds germinated the quickest and at the highest rate after five months of storage. The younger seeds (stored for 1.5 and three months) germinated at the lowest rates. In the high temperature,

32.2°C (90°F), Sedum acre seeds had the highest germination rates when seeds were at their youngest age tested, stored for 1.5 months. As seed is often exposed to varying temperatures, it is difficult to decide the best age for Sedum acre seeds. However, seed stored for 1.5 months would be recommended because germination was around 60% in both the 21.1°C (70°F) and

32.2°C (90°F) growth chambers and it reached 50% germination in both studies in about four days. Older seed germinated at significantly lower percentages in the warmer temperature.

Sedum forsterianum seeds germinated at high percentages in all seed ages tested at

21.1°C (70°F), but germination decreased over time in the 32.2°C (90°F) growth chamber.

Additionally, in the 32.2°C (90°F) growth chamber, seed germination was below 10% at all ages.

In order to recommend Sedum forsterianum seed be used on a green roof, more research would need to be performed regarding how to improve germination at higher temperatures. If temperatures would remain around 21.1°C (70°F), Sedum forsterianum of any age tested (up to

11 months in storage) could be used, but the fastest time to 50% germination occurred in the seed stored for five months.

In the 21.1°C (70°F) growth chamber studies, Sedum reflexum seed had high germination at all ages. The time to 50% germination occurred at the fastest rates when seed was stored for no more than 6.5 months. Conversely, in the 32.2°C (90°F) growth chamber, germination rates decreased significantly over time, with germination percentages of seed stored for three months less than 5%. Due to the significant decrease in germination after three months of storage in the

98 warmer temperature and the similar germination percentages in all ages at the optimal temperature, the best Sedum reflexum seed would be stored for less than three months.

Sedum selskianum seeds had high germination regardless of age in both the

21.1°C (70°F) and 32.2°C (90°F) growth chambers. The quickest time to 50% germination occurred in seeds stored for five months in both temperatures; although, the difference in the time to 50% germination was less than two days between any given age group at both temperatures.

Subsequently, Sedum selskianum seeds were not significantly impacted by seed age.

Unlike Sedum selskianum, Sedum spurium germination rates were influenced by temperature and age. In the 21.1°C (70°F) growth chamber, all seed ages tested produced similarly high germination percentages; however, the oldest seed (stored for 11 months) germinated at the slowest rate. In the 32.2°C (90°F) growth chamber, the youngest seed had the highest germination percentages. Germination in the 32.2°C (90°F) growth chamber declined until seeds were stored for nine months when there was an increase in germination. There was no difference in the time it took to reach 50% germination in the 32.2°C (90°F) study. With the current data, the younger seeds would be recommended as they produced high germination in both temperatures. There is a possibility that Sedum spurium seeds decline in cool storage for several months but then begin to increase germination again when grown in the 32.2°C (90°F) temperature. Further data (after nine months of storage) would be required to determine if this was a random source of variation or if the seeds increase germination rates after nine months of cool storage.

In conclusion, there is a significant effect of seed age on Sedum acre, Sedum reflexum, and Sedum spurium germination. In general, younger seed produced faster and higher germination rates in both the 21.1°C (70°F) and 32.2°C (90°F) temperatures. Sedum forsterianum seed was very sensitive to increased temperature and thus, would be unlikely to

99 produce adequate coverage at any age on a green roof. Sedum selskianum was the only one of the five species tested whose germination rate was unaffected by seed age.

Future Research

Studies similar to those performed for this dissertation need to be performed on other green roof plant species, including other Sedum species, to establish the species that may have potential as a seed installation method for green roofs. Species comparable to Sedum forsterianum should not be used until germination rates are increased at higher temperatures.

Sedum selskianum, on the other hand, would be an ideal species for use in seed installation of a green roof due to its consistent high germination and long storage life.

In general, the successful installation of a green roof through hydroseeding is a viable option. This research has identified that the cost of treating seeds with a prime of water or PEG for 4-12 hours is not advantageous. Creating a recommended seeding application enables future studies to utilize these seeding rates. Additionally, hydroseeding could be utilized in other aspects of the green roof industry to begin growth in modules or on vegetative mats. Most importantly, the cost savings from installing a green roof through the use of a hydroseeder would be significant; thus, potentially increasing the number of green roofs installed throughout the

United States.

100 Bibliography

Ashraf, M., & Foolad, M. (2005). Pre-Sowing Seed Treatment - A Shotgun Approach to Improve Germination, Plant Growth, and Crop Yield under Saline and Non-Saline Conditions. In D. L. Sparks (Ed.), Advances in Agronomy (Vol. 88, pp. 223-271). San Diego, California: Academic Press.

Ashraf, M., Athar, H. R., Harris, P. J., & Kwon, T. R. (2008). Some Prospective Strategies for Improving Crop Salt Tolerance. In Advances in Agronomy (Vol. 97, pp. 45-109). San Diego, California: Elsevier, Inc.

Ball Publishing. (2006). Sky-High and Green. Retrieved November 3, 2007, from GrowerTalks: www.growertalks.com/archive/articles/306.asp.

Baskin, C. C., & Baskin, J. M. (1998). Seeds: Ecology, Biogeography, and Evolution of Dormancy and Germination. San Diego, California: Academic Press.

Basra, A. S. (Ed.). (2006). Handbook of Seed Science and Technology. Binghamton, New York: The Haworth Press.

Benary. (2009). Technical Information. Retrieved from Benary: www.benary.com.

Berghage, R., Jarrett, A., Beattie, D., Kelley, K., Husain, S., Rezai, F., et al. (2007). Quantifying evaporation and transpirational water losses from green roofs and green roof media capacity for neutralizing acid rain. National Decentralized Water Resources Capacity Development Project (NDWRCP) Report 04-DEC-10SG.

Black, M., & Bewley, J. D. (Eds.). (2000). Seed Technology and its Biological Basis. Boca Raton, Florida: CRC Press, LLC.

Burk, S. (2010). CEO/President at Scott's Landscaping. 110 Maple Drive Centre Hall, Pennsylvania.

City of Toronto. (2008). Living in Toronto: Green Roofs. Retrieved June 17, 2008, from City of Toronto Website: http://www.toronto.ca/greenroofs/index.htm.

Copeland, L. O., & McDonald, M. B. (2001). Principles of Seed Science and Technology (4th ed.). Boston, Massachusetts: Kluwer Academic Publishers.

101 DeNardo, J. C., Jarrett, A. R., Manbeck, H. B., Beattie, D. J., & Berghage, R. D. (2005). Stormwater Mitigation and Surface Temperature Reduction by Green Roofs. Transactions of the Asae, 48 (4), 1491-1496.

Elevated Landscape Technologies, Inc. (2006). ELT Easy Green Roof Systems. Retrieved October 16, 2007, from ELT, Inc. Website: http://www.eltgreenroofs.com/index.php.

Farooq, M., Basra, S., & Ahmad, N. (2005, December). Rice Seed Priming. International Rice Research Notes, 45-48.

Geneve, R. (2009, October). Professor of Horticulture at the University of Kentucky. Personal Communication.

Green Roofs for Healthy Cities. (2005). About Green Roofs. Retrieved November 4, 2007, from Green Roofs for Healthy Cities: http://www.greenroofs.org/index.php/about-green-roofs.

Greenroofs.com. (2007). Greenroofs 101. Retrieved May 10, 2008, from Greenroofs.com: http://www.greenroofs.com/Greenroofs101/index.html.

Griswold, N. (2010). Senior Garden Roof Technical Sales Coordinator at American Hydrotech, Inc. Personal Communication.

Halmer, P. (2008). Seed Technology and Seed Enhancement. In Proceedings of International Symposium on Seed Enhancement and Seedling Production Technology (Vol. 771, pp. 17-26). Seoul, Korea: ISHS.

Hansen, K. L., & Zenobia, K. E. (2011). Civil Engineer's Handbook of Professional Practice. Hoboken, New Jersey: John Wiley and Sons, Inc.

Hartmann, H. T., Kester, D. E., Davies, F.T., & Geneve, R. L. (2011). Plant Propagation Principles and Practices (8th ed.). Upper Saddle River, New Jersey: Prentice Hall.

Jelitto. (2012). Jelitto. Retrieved February 29, 2012, from www.jelitto.com.

Kigel, J., & Galili, G. (Eds.). (1995). Seed Development and Germination. New York, New York: Marcel Dekker, Inc.

Kohler, M. (2006, December). Long-Term Vegetation Research on Two Extensive Green Roofs in Berlin. Retrieved October 16, 2007, from Urban Habitats: An Electronic Journal on the Biology of Urban Areas Around the World: http://www.urbanhabitats.org/v04n01/berlin_full.html#cite16.

102 Kohler, M., & Keeley, M. (2005). Berlin: Green Roof Technology and Development. In E. Pledge, Green Roofs: Ecological Design and Construction. Atglen, Pennsylvania: Schiffer Books.

Luckett, K. (2009). Green Roof Construction and Maintenance. McGraw-Hill Companies.

Michel, B. E., & Kaufmann, M. R. (1973). The Osmotic Potential of Polyethylene Glycol 6000. Plant Physiology, 914-916.

Moran, A., Hunt, B., & Jennings, G. (2004). A North Carolina Field Study to Evaluate Greenroof Runoff Quality, Runoff Quantity, and Plant Growth. In Proceedings of the Second North American Green Roof Conference: Greening Rooftops for Sustainable Communities (pp. 446- 460). Portland, Oregon: The Cardinal Group.

National Roofing Contractors Association. (2007, November 1). Green Roof Study Demonstrates Environmental Benefits. Retrieved November 17, 2007, from Professional Roofing: http://www.professionalroofing.net/news/details.aspx?id=33.

Natural Resources Conservation Service. (n.d.). PLANTS Database. Retrieved November 6, 2011, from United States Department of Agriculture Natural Resources Conservation Service: plants.usda.gov.

Nicolas, G., Bradford, K., Come, D., & Pritchard, H. (Eds.). (2003). The Biology of Seeds: Recent Research Advances. Cambridge, Massachusetts: CABI Publishing.

Osmundson, T. (1999). Roof Gardens: History, Design, and Construction. New York: W.W. Norton & Company, Inc.

Peck, S. W., Callaghan, C., Kuhn, M. E., & Bass, B. (1999). Greenbacks from Green Roofs: Forging a New Industry in Canada. Ottawa, Canada: Canada Mortgage and Housing Corporation.

Peck, S., & Kuhn, M. (2001). Design Guidelines for Green Roofs. Retrieved April 6, 2011, from Canada Mortgage and Housing Corporation: http://www.cmhc- schl.gc.ca/en/inpr/bude/himu/coedar/upload/Design-Guidelines-for-Green-Roofs.pdf.

Pictorial Meadows Seeds. (2009). Our Seeds. Retrieved October 11, 2009, from Pictorial Meadows Seeds: www.pictorialmeadows.co.uk/green_roof_mix.

103 Snodgrass, E. C., & McIntyre, L. (2010). The Green Roof Manual. Portland, Oregon: Timber Press, Inc.

Snodgrass, E. C., & Snodgrass, L. L. (2006). Green Roof Plants. Portland, Oregon: Timber Press, Inc.

Stephenson, R. (2002). Sedum Cultivated Stonecrops. Portland, Oregon: Timber Press, Inc.

Taiz, L., & Zeiger, E. (2002). Plant Physiology (3rd ed.). Sunderland, Massachusetts: Sinauer Associates.

Ulrich, R. (1984). View Through a Window May Influence Recovery from Surgery. Science, 224 (4647), 420-421.

United States Environmental Protection Agency. (2011, May 4). State and Local Climate and Energy Program. Retrieved November 6, 2011, from United States Environmental Protection Agency: http://www.epa.gov/statelocalclimate/state/topics/heat-islands.html.

Voelz, J. (2007). The Characteristics and Benefits of Green Roofs in Urban Environments. UC Davis, UC Davis Extension.

Wells, M., & Grant, G. (2004, November). Biodiverse Vegetated Architecture Worldwide: Status, Research, and Advances. Retrieved October 15, 2007, from LivingRoofs.org: http://www.livingroofs.org/images/stories/pdfs/WellsGrant_final.pdf.

Appendix A

Initial Germination Results for 36 Species

Sedum acre Sedum forsterianum 'Oracle'

DAY 50°F 60°F 70°F 80°F 90°F 100°F 50°F 60°F 70°F 80°F 90°F 100°F

1 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 1 0 0 0 0 0 0 0 0 3 0 2 2 15 0 0 0 0 0 0 0 0 4 0 13 7 19 0 1 0 2 0 0 0 0 5 0 20 12 21 0 1 0 3 4 0 0 0 6 0 25 15 24 0 1 0 6 7 0 0 0 7 0 29 19 24 2 1 0 8 11 0 0 0 8 0 30 21 24 3 1 0 12 14 0 0 0 9 0 30 23 24 4 1 0 13 15 0 0 0 10 0 30 24 24 6 1 0 13 16 0 0 0 11 0 30 26 24 7 2 0 17 18 0 0 0 12 0 30 26 24 7 2 0 21 18 0 0 0 13 0 30 26 24 8 2 0 21 18 0 0 0 14 0 30 26 24 8 2 0 21 19 0 0 0 15 1 30 26 24 8 2 0 21 20 0 0 0 16 2 30 26 24 8 2 0 21 20 0 0 0 17 2 30 26 25 8 2 2 21 22 0 0 0 18 3 30 26 25 8 2 3 22 22 0 0 0 19 5 30 26 25 8 2 4 23 22 0 0 0 20 5 30 26 25 8 2 5 23 22 0 0 0 21 5 30 26 25 8 2 5 23 22 0 0 0

Sedum reflexum Sedum selskianum 'Spirit'

DAY 50°F 60°F 70°F 80°F 90°F 100°F 50°F 60°F 70°F 80°F 90°F 100°F

1 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 2 0 0 0 0 0 1 0 0 3 0 3 5 4 0 0 0 3 10 22 8 0 4 0 16 20 8 0 0 0 15 18 28 18 0 5 0 20 24 10 0 0 0 21 19 28 23 0 6 0 21 26 11 0 0 0 22 25 28 26 0 7 0 23 27 11 0 0 0 23 25 29 26 0 8 0 23 27 11 0 0 0 24 26 30 26 0 9 0 23 27 12 1 0 0 24 27 30 26 1 10 0 23 27 13 1 0 0 24 27 30 26 1 11 0 23 27 14 1 0 0 24 27 30 26 1 12 0 23 27 14 1 0 0 24 27 30 26 1 13 0 23 27 14 1 0 0 24 27 30 26 1 14 0 23 27 16 1 0 0 24 27 30 26 1 15 0 23 27 16 1 0 1 24 27 30 26 1 16 0 23 27 16 1 0 1 24 27 30 26 1 17 0 23 27 16 1 0 4 24 27 30 26 1 18 0 24 27 16 1 0 5 24 27 30 26 1 19 0 24 27 16 1 0 7 25 27 30 26 1 20 0 24 27 16 1 0 9 25 27 30 26 1 21 0 24 27 16 1 0 9 25 27 30 26 1

Sedum spurium 'Coccineum' Sedum spurium 'Voodoo'

DAY 50°F 60°F 70°F 80°F 90°F 100°F 50°F 60°F 70°F 80°F 90°F 100°F

1 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 1 0 0 3 0 4 5 0 0 0 0 0 0 6 0 0 4 0 11 11 1 0 0 0 10 4 9 1 0 5 0 17 14 4 0 0 0 19 13 11 1 0 6 0 20 18 4 0 0 0 22 16 13 1 0 7 0 22 20 5 0 0 0 25 19 17 1 0 8 0 22 22 6 0 0 0 25 19 19 1 0 9 0 22 22 7 0 0 0 26 21 19 1 0 10 0 23 23 7 0 0 0 26 23 19 1 0 11 0 24 24 7 0 0 0 26 23 21 1 0 12 0 24 24 9 0 0 0 27 24 22 1 0 13 0 25 24 11 0 0 0 27 24 22 1 0 14 0 25 24 12 0 0 0 27 24 22 1 0 15 0 27 25 12 0 0 0 27 24 22 1 0 16 2 28 25 12 0 0 0 27 24 22 1 0 17 2 28 25 14 0 0 0 27 25 22 1 0 18 4 28 25 14 0 0 0 27 25 22 1 0 19 4 28 25 15 0 0 0 27 25 22 1 0 20 5 28 25 15 0 0 0 27 25 22 1 0 21 5 28 25 15 0 0 0 27 25 22 1 0

Coreopsis Coreopsis Celosia plumosa Cistanthe grandiflora 'Rising grandiflora 'Smart Look Red' grandiflora Sun' 'Presto'

DAY 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F

1 0 0 0 0 0 0 0 0 0 0 0 0 2 0 16 26 0 0 0 0 0 4 0 0 2 3 26 24 28 0 0 0 4 11 6 9 3 4 4 29 27 28 0 0 0 7 14 7 11 6 4 5 30 28 29 0 0 0 10 16 7 16 8 4 6 30 28 30 3 0 0 11 16 8 18 9 4 7 30 29 30 5 3 0 16 17 8 21 12 4 8 30 29 30 5 4 0 18 19 8 24 12 8 9 30 30 30 6 4 0 20 21 9 26 13 8 10 30 30 30 7 5 1 20 21 9 26 15 8 11 30 30 30 7 5 3 20 22 9 26 15 9 12 30 30 30 10 6 3 20 22 10 26 15 9 13 30 30 30 10 7 5 21 23 10 26 15 9 14 30 30 30 10 7 7 21 23 10 26 15 9 15 30 30 30 11 7 7 21 23 11 26 15 10 16 30 30 30 11 7 7 21 23 11 26 15 10 17 30 30 30 11 7 7 21 23 11 26 15 10 18 30 30 30 11 7 7 21 23 11 26 15 10 19 30 30 30 11 8 7 21 23 11 26 15 10 20 30 30 30 13 8 7 21 23 11 26 15 10 21 30 30 30 13 8 7 21 23 11 26 15 10

Table A-5. Cumulative seed germination results for Dianthus gratianopolitanus and Dianthus deltoides in 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F) temperatures (30 seeds per temperature). Dianthus Dianthus deltoides Dianthus deltoides gratianopolitanus Dianthus deltoides 'Confetti Carmen 'Confetti Deep 'Flavora Rose 'Confetti White' Rose' Red' Shades'

DAY 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F

1 0 0 0 0 0 0 0 0 0 0 0 0 2 8 0 8 0 0 22 0 0 2 0 0 3 3 17 22 9 18 20 25 2 2 7 1 2 12 4 18 23 11 27 24 29 4 7 16 9 7 15 5 21 24 11 28 30 29 9 8 21 17 14 19 6 24 24 11 29 30 29 11 13 23 17 18 19 7 25 24 11 29 30 30 16 14 23 20 19 19 8 25 24 12 29 30 30 18 14 27 23 20 20 9 25 24 12 29 30 30 19 15 27 25 23 20 10 25 24 12 29 30 30 22 18 28 27 23 21 11 25 24 12 29 30 30 24 21 28 27 24 23 12 26 24 12 29 30 30 26 22 28 29 26 23 13 26 24 12 29 30 30 28 23 29 29 27 24 14 26 24 12 29 30 30 28 26 29 29 28 24 15 26 24 12 29 30 30 28 26 29 29 28 24 16 26 24 12 30 30 30 28 27 29 29 28 24 17 26 24 12 30 30 30 28 28 29 29 28 25 18 26 24 12 30 30 30 29 28 29 29 28 25 19 26 24 12 30 30 30 29 28 29 29 28 27 20 26 24 12 30 30 30 29 28 29 29 28 27 21 26 24 12 30 30 30 29 29 29 29 28 27

Table A-6. Cumulative seed germination results for Dianthus deltoides, Gaillardia x grandiflora, Gaillardia aristata, and Hypericum cerastoides in 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F) temperatures (30 seeds per temperature). Gaillardia x Dianthus deltoides Hypericum grandiflora Gaillardia aristata 'Confetti Cherry cerastoides 'Arizona Sun 'Mesa Yellow' F1 Red' 'Silvana' Apex'

DAY 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F

1 0 0 0 0 0 0 0 0 0 0 0 0 2 3 0 21 4 9 19 0 0 8 0 0 1 3 19 20 26 13 16 20 10 4 15 0 0 2 4 27 26 29 18 18 20 17 13 22 0 0 3 5 29 29 29 24 25 20 26 21 26 0 0 3 6 30 29 29 26 25 20 28 26 30 1 1 6 7 30 30 29 26 25 20 29 29 30 3 4 7 8 30 30 29 26 25 20 30 29 30 10 7 7 9 30 30 29 26 27 20 30 29 30 10 9 7 10 30 30 29 26 27 20 30 29 30 15 9 7 11 30 30 29 27 27 20 30 29 30 17 10 7 12 30 30 29 28 27 20 30 29 30 18 12 7 13 30 30 29 28 27 20 30 29 30 18 14 7 14 30 30 29 28 27 20 30 29 30 19 15 7 15 30 30 29 28 27 20 30 29 30 19 16 7 16 30 30 29 28 27 20 30 29 30 19 16 7 17 30 30 29 28 27 20 30 29 30 19 17 7 18 30 30 29 28 27 20 30 29 30 19 18 8 19 30 30 29 28 27 20 30 29 30 19 18 8 20 30 30 30 28 27 20 30 29 30 19 20 8 21 30 30 30 28 27 21 30 29 30 22 20 8

Table A-7. Cumulative seed germination results for Lavandula angustifolia, Pentas lanceolata, and Physostegia virginiana in 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F) temperatures (30 seeds per temperature). Lavandula Lavandula Pentas lanceolata Physostegia angustifolia angustifolia 'F1 Kaleidoscope virginiana 'Crystal 'Munstead 'Vicenza Blue' Pink' Peak White' Variety'

DAY 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F

1 0 0 0 0 0 0 0 0 0 0 0 0 2 15 0 21 2 0 0 0 0 0 0 0 11 3 28 22 23 14 15 1 0 0 0 1 1 15 4 29 27 26 19 23 4 0 0 14 9 12 19 5 29 29 27 21 26 5 16 11 18 20 21 19 6 29 29 27 22 28 6 24 15 19 21 21 20 7 29 29 28 23 28 8 25 26 24 22 22 20 8 29 29 28 23 28 9 25 27 24 22 22 20 9 29 29 28 23 28 11 25 27 25 22 23 21 10 29 29 28 24 28 14 25 27 25 24 23 21 11 29 29 28 25 28 14 25 27 25 24 23 21 12 29 29 28 25 28 17 25 27 25 25 24 21 13 29 29 28 25 28 17 26 27 25 26 25 22 14 29 29 28 25 28 17 26 27 25 26 25 22 15 29 29 28 25 28 17 26 27 25 26 26 22 16 29 29 28 25 28 17 26 27 25 26 26 22 17 29 29 28 25 28 17 26 27 25 26 26 22 18 29 29 28 25 28 17 26 27 25 26 26 22 19 29 29 28 25 28 18 26 27 25 26 26 22 20 29 29 28 25 28 19 26 27 25 26 27 22 21 29 29 28 26 28 19 26 27 25 26 27 22

Prunella Prunella Ptilotus exaltatus Rudbeckia hirta grandiflora grandiflora 'Joey' 'Cappuccino' 'Freelander Blue' 'Freelander Mix'

DAY 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F

1 0 0 0 0 0 0 0 0 0 0 0 0 2 13 22 4 6 19 7 28 30 25 1 2 10 3 20 24 14 19 21 14 28 30 27 11 10 16 4 25 25 19 23 21 21 30 30 28 19 16 20 5 27 28 24 27 27 22 30 30 28 23 20 22 6 28 28 25 27 28 23 30 30 28 25 21 24 7 28 28 27 28 28 25 30 30 28 26 24 24 8 28 28 27 28 28 25 30 30 28 26 25 24 9 28 29 27 29 29 26 30 30 28 27 25 24 10 29 29 28 29 30 26 30 30 28 27 25 24 11 29 29 28 29 30 27 30 30 28 27 25 24 12 30 29 29 29 30 28 30 30 28 27 25 24 13 30 29 29 29 30 28 30 30 28 27 25 24 14 30 29 30 29 30 28 30 30 28 27 25 24 15 30 29 30 29 30 28 30 30 28 27 25 24 16 30 29 30 29 30 28 30 30 28 28 25 24 17 30 29 30 29 30 28 30 30 28 28 25 24 18 30 29 30 29 30 28 30 30 28 28 25 24 19 30 29 30 29 30 28 30 30 28 28 25 24 20 30 29 30 29 30 28 30 30 28 28 25 24 21 30 29 30 29 30 28 30 30 28 28 25 24

Rudbeckia hirta Rudbeckia hirta Salvia farinacea Sanvitalia speciosa 'Maya Apex C' 'Tiger Eye Gold' 'Fairy Queen' 'Million Suns'

DAY 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F

1 0 0 0 0 0 0 0 0 0 0 0 0 2 7 11 20 1 0 0 0 4 13 4 2 0 3 28 25 23 4 1 1 7 12 16 6 4 0 4 29 29 26 8 3 5 14 17 20 13 9 0 5 30 29 27 11 4 7 14 18 22 20 16 0 6 30 29 28 13 8 9 16 18 25 23 18 0 7 30 30 29 16 15 10 16 18 25 23 24 2 8 30 30 29 18 18 11 17 19 25 24 24 4 9 30 30 29 19 21 12 17 19 25 24 27 5 10 30 30 30 20 22 12 18 21 25 24 28 6 11 30 30 30 22 23 12 18 21 25 24 28 8 12 30 30 30 23 23 14 18 21 25 24 28 10 13 30 30 30 24 24 16 18 21 25 24 28 11 14 30 30 30 24 24 16 18 21 25 24 28 12 15 30 30 30 25 25 20 18 21 25 24 28 12 16 30 30 30 27 25 20 18 21 25 24 28 12 17 30 30 30 27 26 21 18 21 25 24 28 12 18 30 30 30 28 26 22 18 21 25 24 28 13 19 30 30 30 28 27 22 18 21 25 24 28 14 20 30 30 30 29 27 22 19 21 25 24 28 15 21 30 30 30 29 27 22 19 21 25 25 28 16

Table A-10. Cumulative seed germination results for Viola wittrockiana and Zinnia marylandica in 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F) temperatures (30 seeds per temperature). Viola x Viola wittrockiana Viola x Zinnia marylandica wittrockiana 'Fizzy wittrockiana 'Zahara Coral 'MatrixTM Rose Lemonberry' 'MatrixTM Rose' Rose' Wing'

DAY 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F 60°F 70°F 80°F

1 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 1 0 0 0 1 21 25 26 3 1 7 0 0 12 2 4 5 3 25 27 28 4 5 11 1 11 15 3 13 18 13 28 29 28 5 19 14 1 16 19 5 17 19 16 28 29 29 6 22 15 1 22 20 5 20 20 20 29 29 29 7 24 17 2 24 22 5 26 23 21 29 30 29 8 25 17 4 25 27 6 28 26 25 29 30 29 9 25 20 4 27 29 7 29 27 25 29 30 29 10 25 21 4 30 29 7 30 29 25 29 30 29 11 25 22 4 30 29 8 30 29 25 29 30 29 12 25 22 4 30 29 8 30 29 25 29 30 29 13 25 22 7 30 29 10 30 29 25 29 30 29 14 25 22 7 30 29 12 30 29 25 29 30 29 15 25 22 8 30 29 13 30 29 25 29 30 29 16 26 22 8 30 29 13 30 29 25 29 30 29 17 26 22 14 30 29 16 30 29 25 29 30 29 18 26 22 15 30 29 17 30 29 25 29 30 29 19 28 22 15 30 29 17 30 29 25 29 30 29 20 29 23 16 30 29 17 30 29 25 29 30 29 21 29 23 19 30 29 19 30 29 25 29 30 29

Table A-11. Cumulative seed germination results for Zinnia marylandica in 15.5°C (60°F), 21.1°C (70°F), 26.7°C (80°F) temperatures (30 seeds per temperature).

Zinnia marylandica Zinnia marylandica 'Zahara Scarlet' 'Zahara White'

DAY 60°F 70°F 80°F 60°F 70°F 80°F

1 0 0 0 0 0 0 2 25 26 27 23 24 28 3 29 29 27 29 27 29 4 29 29 27 30 28 30 5 29 29 28 30 29 30 6 29 29 28 30 29 30 7 30 29 28 30 29 30 8 30 29 28 30 29 30 9 30 29 28 30 29 30 10 30 29 28 30 29 30 11 30 29 28 30 29 30 12 30 29 28 30 29 30 13 30 29 28 30 29 30 14 30 29 28 30 29 30 15 30 29 28 30 29 30 16 30 29 28 30 29 30 17 30 29 28 30 29 30 18 30 29 28 30 29 30 19 30 29 28 30 29 30 20 30 29 28 30 29 30 21 30 29 28 30 29 30

Appendix B

Additional Tables From Chapter 3

Table B-1. Levels of significance of effects and interactions for germination rates for the 12-48 hour priming study. Values are P-values, ns = not significant at α = 0.05. Plant Species Length of Priming Sedum acre 0.0407 Sedum forsterianum No statistics run Sedum reflexum 0.0238 Sedum selskianum 0.0222 Sedum spurium 0.0506

Table B-2. Levels of significance of effects and interactions for germination rates for the 4-hour to 12-hour priming study. Values are P-values, ns = not significant at α = 0.05. Plant Species PEG Concentration Length of Priming PEG x Priming Time Sedum acre ns ns ns Sedum forsterianum No statistics run No statistics run No statistics run Sedum reflexum ns ns ns Sedum selskianum 0.0206 ns ns Sedum spurium ns ns 0.0399

Table B-3. Levels of significance of effects and interactions for time to 50% germination for the 4-hour to 12-hour priming study. Values are P-values, ns = not significant at α = 0.05. Plant Species PEG Concentration Length of Priming PEG x Priming Time Sedum acre ns ns ns Sedum forsterianum No statistics run No statistics run No statistics run Sedum reflexum ns ns ns Sedum selskianum ns ns ns Sedum spurium ns <0.0001 ns

Appendix C

Additional Tables From Chapter 5

Table C-1. Levels of significance of effects and interactions for germination rates for the 2011 Millennium Building study. Values are P-values, ns = not significant at α = 0.05. Plant Species PEG Concentration Length of Priming PEG x Priming Time Sedum acre ns ns ns Sedum forsterianum ns ns ns Sedum reflexum ns ns ns Sedum selskianum ns ns ns Sedum spurium ns ns ns

Table C-2. Levels of significance of effects and interactions for germination rates for the 2011 module study on day 21. Values are P-values, ns = not significant at α = 0.05. Plant Species PEG Concentration Length of Priming PEG x Priming Time Sedum acre ns ns 0.0055 Sedum forsterianum ns ns ns Sedum reflexum ns ns ns Sedum selskianum ns ns ns Sedum spurium ns ns 0.0164

Table C-3. Levels of significance of effects and interactions for germination rates for the 2011 module study on day 26. Values are P-values, ns = not significant at α = 0.05. Plant Species PEG Concentration Length of Priming PEG x Priming Time Sedum acre ns ns ns Sedum forsterianum ns ns ns Sedum reflexum 0.0024 ns ns Sedum selskianum ns ns ns Sedum spurium ns ns ns

Table C-4. Levels of significance of effects and interactions for germination rates for the 2011 module study on day 32. Values are P-values, ns = not significant at α = 0.05. Plant Species PEG Concentration Length of Priming PEG x Priming Time Sedum acre ns ns ns Sedum forsterianum ns ns ns Sedum reflexum ns ns ns Sedum selskianum ns ns ns Sedum spurium ns 0.013 ns

Table C-5. Levels of significance of effects and interactions for germination rates for the 2011 Root Cellar roof study on day 12. Values are P-values, ns = not significant at α = 0.05. Plant Species PEG Concentration Length of Priming PEG x Priming Time Sedum acre ns ns ns Sedum forsterianum ns ns ns Sedum reflexum ns ns ns Sedum selskianum ns 0.0016 ns Sedum spurium ns ns ns

Table C-6. Levels of significance of effects and interactions for germination rates for the 2011 Root Cellar roof study on day 34. Values are P-values, ns = not significant at α = 0.05. Plant Species PEG Concentration Length of Priming PEG x Priming Time Sedum acre ns ns ns Sedum forsterianum 0.01 ns ns Sedum reflexum ns ns ns Sedum selskianum ns ns ns Sedum spurium ns ns ns

VITA Kathryn Lyn McDavid

EDUCATION:

The Pennsylvania State University, University Park, PA 16802 Ph.D. in Horticulture; GPA of 3.95; 2007-2012 The Pennsylvania State University, University Park, PA 16802 B.S. in Horticulture with Biology minor; GPA of 3.5; 2004-2007

EXPERIENCE AND ACTIVITIES:

International Plant Propagators’ Society (IPPS) Publicity Committee member, 2012 Posters and Research Grants Committee member, 2009-2012 Coordinator of Undergraduate Recruiting for the Penn State Horticulture Department, 2009-2012 Penn State Undergraduate Horticulture Recruiter and Representative on the Student Recruitment and Enrollment Committee, 2009-2012 Penn State College of Agricultural Sciences Recruiting and Marketing Committee member, 2010- 2012 Penn State College of Agricultural Sciences Instruction and Curricular Affairs Committee graduate student representative, 2010-2011 Teaching assistant for Perennial Plant ID, Plant Propagation, and Flower Arranging courses at Penn State, 2005-2009

PUBLICATIONS AND PRESENTATIONS:

Fivek, M.; Ziegler, J.; and McDavid, K. (2012). How do you know if your marketing is effective? Presented at National Agricultural Alumni and Development Association (NAADA) Conference in Lexington, Kentucky. Sanford, K.; Sanford, D.; and Berghage, R. (2008). Multi-Campus Plant Propagation Course. Combined Proceedings of the International Plant Propagators’ Society 58: 381-384.

HONORS AND ACHIEVEMENTS:

Gamma Sigma Delta Honor Society member, inducted 2009 Pi Alpha Xi Honor Society member, inducted 2005 American Society for Horticultural Science Outstanding Horticulture Student, 2007 American Society for Horticultural Science Collegiate Scholar’s Award, 2006 President’s Award for Freshman, 2004

MEMBERSHIPS:

International Plant Propagators’ Society (IPPS) member, 2008-2012 American Society for Horticultural Science (ASHS) member, 2008-2012 Perennial Plant Association (PPA) member, 2008-2012