Grow Perennials

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Growing Perennials Michigan State University Agricultural Experiment Station and Cooperative Extension Service Research Report Anne M. Hanchek, University of Minnesota; J. Lee Taylor, Pamela Allenstein, and Arthur C. Cameron, Michigan State University

Issued November 1994 33 pages

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Growing Perennials History of Perennials in the Landscape Perennials have long been popular with gardeners throughout the world because they are relatively easy to grow and offer diversity of color, form and bloom sequence. A border bed of only perennials was first suggest- ed in 1890 by George Nicholson, curator of the Royal Botanic Gardens at Kew, England. A movement began away from regi- mented rows of bedding plants in the flower beds of the mid- Victorian period (1870s) that Anne M. Hanchek, Assistant professor, Dept. of continued into the 1900s. Tender Horticultural Science, University of Minnesota bedding plants returned to favor J. Lee Taylor, Professor emeritus Pamela Allenstein, Former student, and in the early 1900s, and use of Arthur C. Cameron, Associate professor, perennials decreased, while Department of Horticulture, annuals in massed beds for sum- Michigan State University mer show attracted the public. The return to the use of perenni- North Central Regional als started about 1914 and con- Extension tinues today. Publication No. 556

Where to find it

Page Page History of Perennials in the Books for Further Reading ...... 16 Landscape ...... 1 Perennials with Special Features What are Perennials? ...... 2 (Table) ...... 17 Why use Perennials? ...... 3 Selecting Perennials ...... 19 Designing with Perennials ...... 4 Perennial Selection/Care Guide (Table) ...... 20 Color Guide (Table) ...... 7 Bloom Chart ...... 27 Putting It All Together ...... 9 Cross-reference Index ...... 29 Culture of Perennials ...... 10 Spring Freeze Map ...... 32 Getting Started ...... 11 Hardiness Zone Map ...... 32 Controlling Pests and Diseases . . . 15

1 The 19th century Today, limited space The maintenance Example British plant experts often makes it impos- required for perenni- What are Common name: William Robinson sible or undesirable to als also varies with Garden mum and Gertrude Jekyll devote an area entire- Perennials? the species. For exam- played prominent ly to growing only ple, chrysanthemum Botanical name: roles in popularizing one type of plant, and delphinium need Dendranthema the perennial border such as perennials. The term “perenni- attention each year, grandiflora and developing The trend is toward als” commonly whereas hosta, peony Synonym: guidelines for its mixed borders or means “hardy herba- and balloon flower Chrysanthemum X design. They grouped beds that include ceous ornamental generally require little morifolium border perennials trees, shrubs, peren- plants.” Hardy peren- care after they are together and tiered nials, bulbs, annuals nials are, with some established. A rela- Cultivars: them with the tallest and biennials. This exceptions, non- tively low–mainte- ‘MinnGopher’ plants (such as del- allows you to select woody plants having nance garden is possi- ‘Snowsota’ phiniums) in the plants that go well roots that live ble, but it requires ‘Mellow Moon’ back and lower grow- together to create through the winter careful selection of Most modern refer- ing plants in the year-round color and while the tops die plants well suited to ence books on peren- front to separate the interest. back to the ground, the climate and nials refer to the border from the lawn. particularly in north- planted in an appro- There is also a move- plants by botanical The border was set ern climates. priate location. ment toward less for- name, so learning to against the backdrop mal, low–mainte- This distinction sepa- The following peren- use these specific of a hedge, usually nance gardens. rates hardy perennials nials will be excluded names can help you yew or boxwood, or a Perennials may be from tender perenni- from this bulletin. find information weathered brick wall. planted directly in als and annuals, Trees and shrubs, more quickly and Careful selection and lawns or in ground which flower, set seed although they are accurately. placement combined covers, such as peri- and die in the perennials, have harmonious color winkle or English autumn frosts; and woody plant parts schemes and con- ivy—a practice also from biennials, that normally do not trasting forms to pro- known as “naturaliz- which take two years die back to the vide interest and a ing.” Perennials hav- to complete the life ground each winter. sequence of continu- ing a low, spreading cycle. In the first year Bulbs, tubers and ous bloom. habit may also be biennials form low corms have special- Perennial borders in used instead of more rosettes of leaves; the ized methods of food this form, however, traditional ground next year, they send storage and are usual- presented certain dis- covers. Dried flowers up flowering stems ly treated separately, advantages. They and leaves are left on and die. Many bien- as are ferns and the required a great deal the plants for winter nials seem to be less common wild- of space and atten- interest and for use in perennial simply flowers. tion and could be dried arrangements. because they reseed Perennials are usually viewed from only one More ornamental themselves easily. sold under their side. The background grasses are used, as Some perennials will botanical names hedge competed for well as massings of last almost indefinite- (genus, species, culti- light and slowed air one or a limited num- ly. Others tend to be var) by the more rep- circulation, encourag- ber of other perenni- short-lived and many utable nurseries. This ing the back row to als. By combining last only a few years. is because common lean forward unless many species, you Peony, daylily and iris names can be confus- staked. These faults can create a spectacu- are extremely long- ing: one plant may inspired the island lar display. lived, while have three different bed concept at columbine, shasta common names, or Bressingham Gardens daisy and lupine tend one common name in Norfolk, England, to be short-lived, may refer to three dif- in the 1950s. flowering for two or ferent plants. When planted in rela- three years. When However, every plant tively narrow islands, selecting plants, has only one unique the flowers could be remember that botanical name. viewed from all direc- “perennial” doesn’t Occasionally, these tions and shading by necessarily mean names are changed hedges or walls was “perpetual.” by plant scientists to eliminated. Taller better describe the specimens were plant. When that placed in the middle happens, the old of the bed, their name becomes a syn- height usually no onym for the new. more than half the width of the bed.

2 conditions are listed Why use on the right. Problem Area Beautification Guide A carefully planned Perennials? perennial garden pro- Wet Areas Fertile Soil Rocky Areas vides continuous Iris sibirica Astilbe Aquilegia Caring for perennials flowering from early Monarda didyma Delphinium Armeria maritima can be a type of cre- spring through late Viola odorata Dendranthema Aurinia saxatilis ative expression. fall. Ornamental grandiflora Perennials offer a grasses and other wide variety of forms, plants with persistent colors, textures and flowers have winter Dry Areas Infertile Soil For Naturalizing sizes. They are long- interest, too. Achillea Asclepias tuberosa Ajuga lived, compared with Combine perennials Asclepias tuberosa Baptisia australis Helianthus annuals, and can with annuals, ground Hemerocallis Gypsophila helianthoides require relatively low covers, shrubs and paniculata Tradescantia X maintenance. They trees to create a spec- andersoniana can also provide vig- tacular landscape that orous new stock for is continually chang- Low Plants Shade Tall Plants transplanting and ing in texture, form trading with neigh- and color. Artemisia Astilbe Eupatorium bors and friends. `Silver Mound’ Heuchera sanguinea maculatum Dianthus Hosta Phlox subulata Perennials are versa- Calamagrostis tile. From the thou- acutiflora sands of species and Hibiscus moscheutos varieties available, you can select perennials that will thrive in any type of site, from wet to dry, fertile to infertile, sun to deep shade. They often provide the solution for problem areas, such as steep slopes, hillsides and rocky outcroppings. Notable examples of perennials that will thrive in these special

3 DESIGNING WITH PERENNIALS

Why design at all? Step #1: as red maples, have a INFORMAL DESIGN Designing a perennial Determine the shallow root system flower garden and and will compete seeing it develop point(s) of with perennials for before your eyes can moisture. be rewarding. It takes viewing. time, knowledge and Place beds or borders Step #2: experience to prepare where they can be Consider exist- a good plan. The readily seen and planning stage is too admired. Try to locate ing conditions. often overlooked by them in areas of high Use the grid sheet on the impatient garden- visibility, such as the page 8 to sketch the er, and this results in front yard, near win- layout of your yard, a haphazard collec- dows, the porch or or create your own tion of plant materi- patio, while keeping grid using 1/4-inch als. The eye needs a in mind other factors graph paper and a sense of order. Too such as soil type, scale of 1/4 inch = 1 many variations in drainage, pH and foot. If the scale is sizes, shapes, colors light. Also consider insufficient, use 1/4 and textures create that certain trees, inch = 2 feet. With a confusion. Remember such as black walnut tape measure, deter- that the most spec- and butternut, pro- mine the size of the tacular gardens all duce a chemical in area you wish to begin with a carefully their roots that is plant. Carefully thought-out design toxic to many plants, record the location of that has strong lines including peonies. existing plants that and structure. Locate susceptible you want to keep and plants a minimum other permanent or distance of 60 feet temporary fixtures, from such trees. such as a compost Perennials with shal- pile, posts, a water low root systems are spigot, trash barrels, less likely to be affect- septic tanks and drain ed. Some trees, such field. Indicate any

USING A GRID: Five Steps in Sketch the layout of your yard, recording Designing a all existing features and plants. Perennial EXISTING YARD FORMAL DESIGN Garden

Step #1— Determine the point(s) of viewing. Step #2— Consider existing conditions. Step #3— Decide on style— either informal or formal. Step #4— Choose type of display. Step #5— Select plants.

4 Perennials are available in many heights, shapes and textures.

low or high points • Consider the style of display can break Plant Form Spread and shaded areas of of the house and up large, open areas. Each perennial has a the property. select the style of gar- A newly planted bed You do not need to general shape or Determine the soil den that will comple- can look rather bare if segregate perennials form. Basic forms are type(s) such as clay, ment it best. plants are spaced at in the garden. Many vertical or columnar, sand or loam; acid or recommended dis- can be naturalized such as delphinium; neutral; well drained Step #4: tances for mature along a stream, in mounded, such as or poorly drained. specimens. To avoid Choose type of lowlands or in dry astilbe; and horizon- this bareness, space Step #3: display. meadows so that they tal or prostrate, such plants closer together Decide on Three types of dis- look as if they are as creeping phlox. and transplant a few plays are commonly part of the natural Most perennials fall out of the bed as they style—either used for perennial landscape. Some can in between these become crowded. informal or gardens—the border, be naturalized in three forms. Use a This will also help the island bed and lawns or ground cov- variety of forms to control weeds. Or use formal. the naturalized area. ers, and a number create the most pleas- annual plants in bare An informal style fol- A border is a cultivat- can be used as ing effect. areas until the peren- lows the natural tered area that bounds ground covers them- Height nials grow into their rain by using curved, an expanse such as a selves. You can use allotted space. You flowing lines. It cre- lawn, walkway, drive- many wildflowers Perennials vary in also can cover bare ates balance without way or wall. If it is and ferns in such height from the tiny areas with a 2- to 4- being symmetrical flush against a wall or locations. Thymus pseudolanugi- inch layer of mulch. and highlights exist- hedge, the border Step #5: nosus (woolly The plants will fill in ing and future plant should not be any thyme)—about 1/2 the bare spaces as the specimens. A formal wider than 4 to 6 feet Select plants. inch tall—to the lofty garden matures over style uses straight, for ease of mainte- When selecting Hibiscus moscheutos a few years. geometric lines to nance. For a wider plants, make a list of (rose mallow)—up to Texture determine the shape border, plan a narrow your favorites. 8 feet tall. The stan- of the bed. It often path between the Consider the space dard method of This characteristic relies on symmetry, wall and the garden limitations of the site: arranging heights is refers to the overall i.e., matching one for access. The path would smaller, com- “stair-stepping.” appearance of a leafy side of the garden will be hidden from pact plants be appro- Shorter plants are plant, not to the feel with the other. The view and will priate? Should taller placed in front, medi- of it. Perennials are rectangular shape can improve air circula- plants with spreading um height plants in commonly grouped be repeated in other tion behind the habits be included? the middle and taller as coarse, medium or architectural ele- tallest plants, which Match the soil type, plants in the back. fine textured. Create ments, such as the should reduce disease light levels and site Break up this progres- spatial illusions by house, pool, lawn or problems. For a pleas- climate with the sion a bit to keep the using different tex- patio. ing relationship requirements of pre- garden interesting tures. Plants with and more natural. Be coarse textures appear Most decisions on between the depth of ferred plants. the border and the Carefully consider careful not to com- closer than they real- style are a matter of pletely hide smaller ly are, while those personal preference. size of the yard, do individual plant char- not allow it to exceed acteristics, as well as plants behind taller with fine textures Here are a few points specimens. recede into the dis- to consider: one-quarter of the the overall character total width of your of the garden. Several tance. Examples are: • If your property has yard. books and catalogs coarse texture—berge- no outstanding natu- nia, hollyhock, An island bed is a cul- on perennials are ral features and is rel- available and include Oriental poppy; atively flat, you may tivated area surround- medium texture— ed by an open pictures and other use either style. information that can astilbe, iris, rudbeck- expanse, such as a ia; fine texture— • If your yard is irreg- lawn. It is accessible help you select plants. `Silver Mound’ ularly shaped with from all sides, which artemisia, baby’s slopes, hills, rock out- makes it easier to breath, lavender. croppings or mature maintain. It admits specimen trees, the more sunlight and informal style is pre- encourages better air ferred. circulation. This type

5 6 Color select and arrange Warm, vibrant colors, ever, because they are viewing and in mass- species and cultivars such as red, orange quite intense and can es. Perennials are noted to create pleasing and and yellow, tend to overpower the rest of for their usually Many gardeners use harmonious displays. stand out in the land- your garden. Cool, short-lived but various color (For more informa- scape. They can also peaceful colors, such remarkable flower schemes. tion on color use, see make a distance seem as blue, green and color. Thus, an under- Extension bulletin shorter. For these rea- purple, tend to recede standing of color and NCR-211, Flower sons, use warm colors into the landscape. the relationship of Arranging, for sale as accents or for long- They are especially colors is important. only.) distance viewing. Use effective for close This will allow you to them carefully, how-

COLOR GUIDE

Blue to Purple Dianthus Hemerocallis Ajuga Dicentra Iris Gray to Blue Aquilegia Echinacea Ligularia Foliage Aster Eupatorium Lysimachia Achillea Brunnera Geranium punctata Artemisia Campanula Hemerocallis Oenothera Cerastium Centaurea Heuchera Papaver orientale Dianthus Using One montana Iris Rudbeckia Echinops Color Delphinium Lobelia cardinalis Sedum Festuca cinerea Erigeron Lychnis Trollius Gypsophila A monochromatic Hosta Paeonia Lavandula scheme includes dif- Iris Phlox White Sedum ferent flowers that have various tints Lavandula Physostegia Arabis albida Thymus and shades of a single Liatris Saponaria Aruncus color, such as blue. Linum perenne Aster Variegated Another popular Foliage color is white. Several Mertensia Yellow to Astilbe famous gardens are Nepeta Orange Cerastium Aegopodium fashioned around an Phlox Achillea Dendranthema Ajuga all-white theme, such Heuchera as the white garden at Platycodon ‘Coronation Dianthus Sissinghurst Castle in Salvia Gold’ Dicentra Hosta Kent, England, Tradescantia Anthemis Dictamnus Lamiastrum designed by Vita tinctoria Lamium Sackville-West after Veronica Echinacea World War II. Viola Asclepias Galium Miscanthus Choosing a particular tuberosa Goniolimon Polygonatum color can be especial- Aurinia saxatilis Pulmonaria ly effective in com- Pink to Red Gypsophila plementing the color Achillea Coreopsis Hosta Sedum of your house. millefolium Dendranthema Iberis Thymus Anemone Euphorbia Iris Using Armeria Gaillardia Leucanthemum Aster Geum Paeonia Several Astilbe Helenium Phlox Colors Centranthus Helianthus Veronica Dendranthema Heliopsis Yucca An analogous scheme uses two or more hues that are adjacent silver-leaved plants A polychromatic or neighboring on may be used to blend scheme includes any the color wheel, such areas where colors and every combina- as red, red-violet and meet. tion of colors. This violet. Another possi- type of design yields ble scheme is orange, A semi-chromatic a great variety of col- yellow-orange and color scheme divides ors and can be very yellow. the color wheel in festive. It is impor- half and uses any A complementary tant to note, howev- three adjoining col- scheme uses colors er, that even gardens ors, such as blue, vio- opposite each other of this type with let and red; or red, on the color wheel, seemingly haphazard orange and yellow. such as yellow and arrangements achieve This approach is very violet, red and green, their success only popular today. or orange and blue. through careful plan- White-flowered and ning.

7 Grid Sheet for Planning Your Garden

8 This bed is designed to provide continuous bloom Time and throughout the growing season. Duration of Bloom

Perennials vary considerably in when and how long they flower. A bloom chart, such as the one in the back of this bulletin (p. 27), will help you coordinate flowering periods to prolong a colorful display or to concen- trate color during a particular time. If you own a summer home, for example, you might want to plant an August-flowering perennial bed. If you live in your home year round, you might want to plan a garden for spring, summer and fall color. Although perennials can provide continuous bloom throughout the growing sea- Perennials son, there are usually three or four peak PUTTING IT ALL TOGETHER for periods when the display is at its best. Using the grid sheet, ments. Be sure to Beginners Remember also that determine the include your favorites perennials are grown approximate loca- as well as species that for other attributes tion, size and shape provide special attri- Achillea than flowers. Colorful of the perennial bed butes, such as fra- or interesting foliage or border. Draw an grance. Take into Arabis and fruit, unique outline of the bed account design fac- forms and fragrance alone on a second tors such as form, Brunnera also provide interest. sheet, using a larger spread and texture, as macrophylla In a garden timed for scale, such as 1 inch = well as cultural continuous bloom- 1 foot or 1/2 inch = 1 requirements, to cre- Coreopsis ing, expect to see a foot. Lightly pencil in ate a varied, interest- Dicentra fair amount of green approximate height ing display. Make up foliage with intermit- requirements of a tentative plant list spectabilis tent flowers, rather plants in certain and check availability many of each peren- Echinacea than a solid mass of in catalogs. Be sure to regions of the garden: nial you need, based purpurea color. (See the Bloom tallest plants in the repeat some perenni- on recommended Chart on page 27.) back of a border or in als to keep the garden plant spacings. Use Heliopsis unified in appear- the center of an groups of three to six helian- island bed. Keep in ance. Decide how for best results. mind your color thoides scheme and desired plant heights; consult Hemerocallis the table on selecting Hosta perennials (p. 20) to choose plants that Miscanthus meet these require- sinensis Nepeta Phlox subulata Physostegia virginiana Rudbeckia fulgida ‘Goldsturm’ Sedum ‘Autumn Joy’ 9 CULTURE OF PERENNIALS

intended. If this hap- Prepare pens, add additional soil or mulch. This Simple Tools for Perennial Culture the Soil can be a problem after rototilling, which fluffs up the soil. It’s a good idea to test your soil in the fall to Use a garden hose to determine the pH establish the outline and the nutrients of each bed or border. required. Your county The hose will not get Cooperative in the way of digging Extension Service as will a string and office can provide stakes. It can be information on how moved easily and is to take a soil sample especially useful and may be able to when laying out help interpret the curved or circular results. Soil tests con- beds. ducted by profession- Work the soil to a al laboratories are depth of 8 to 10 inch- generally more accu- es, or at least deep rate than those made enough to provide with inexpensive soil adequate space for testing kits. If you the plants’ root sys- wait until spring to tems—perhaps only a test the soil, it may few inches for a rock take a few weeks to garden. Incorporate obtain the results organic matter, such because soil testing as peat moss, com- labs are busiest at post or leaf mold at that time. this time—up to 4 Prepare beds in the inches, if available. fall before spring You can use hand planting so the soil tools or power tillers. can settle. If the bed site has poorly drained soil, You can prepare beds select species that will in the spring as long tolerate moist or wet as you allow suffi- sites (see Perennials cient time for the soil with Special Features to settle before you on page 18), raise the plant—at least 2 bed to improve weeks—or after one drainage or choose a good, soaking rain. If better site. you transplant in extremely loose soil, the crowns may end up an inch or so higher than you

Preparation of beds is important because it will be a long- term planting.

10 or aluminum sulfate soil the following increase plant hardi- Eliminate Fertilization as recommended by year to be sure the pH ness. Apply only a the soil test report, or is at the recommend- thin layer of mulch all Weeds is Important according to the rates ed level. If not, top- to heavier clay soils in Chart 2. Rates for dress the soil with because these soils do aluminum sulfate limestone or alum- not drain as rapidly and iron sulfate need inum sulfate. and may stay wet too You must eliminate You may need to to be five times those long. You may need To increase soil mois- all weeds during this apply fertilizer when given for sulfur. to add organic mulch ture retention, spread initial soil prepara- you prepare the beds. each year as it decom- Adding generous a 2- to 3-inch layer of tion period before Follow the recom- poses. Plastic mulch amounts of organic mulch over the sur- plants are added or mendations of the is not recommended. matter will also help face of newly pre- seeds are sown. soil test report. If you Rock mulch is best to lower soil pH and pared beds. Use bark Untold difficulties didn’t test the soil, used only in rock gar- keep it at the desired chips, leaf mold, pine arise when perennial apply a complete fer- dens. weeds, such as tilizer, such as 5-10-5, level. Normally, pH needles, well rotted bindweed or quack- at a rate of 2 pounds needs to be adjusted sawdust or compost. grass, grow through a (4 rounded cups) per only once, but it is This will also help carefully planted bed. 100 square feet. Work desirable to test the suppress weeds and Because of the diver- the fertilizer into the sity among perenni- soil as you prepare CHART 1. als, it is risky to the bed. Pounds of ground limestone needed per 100 chemically treat The ideal soil pH for weeds in close prox- square feet to raise pH to 6.5. most perennials is imity to valuable slightly acidic (6.0 to plantings. It may be 6.8). If the pH is too Soil pH Sandy loam Loam Clay loam possible, however, to low or too high (as treat individual weeds 5.0 8 10 15 determined by a soil with a herbicide rec- test), adjust it at the 5.5 6 8 10 ommended for use on same time you apply perennials. 6.0 3 4 6 fertilizer. To raise the Work the bed for one pH (make it more year before planting alkaline), add ground CHART 2. to kill all weed limestone as recom- Pounds of sulfur needed per 100 square feet seedlings as seeds ger- mended by the soil to lower pH to 6.0. minate. test report, or at the rates indicated in Chart 1. Soil pH Sandy loam Loam Clay loam To lower the pH 7.5 1.8 2.5 3.9 (make it more acidic), 7.0 1.4 2.0 3.1 add sulfur, ferrous 6.5 0.8 1.2 1.9 sulfate (iron sulfate) GETTING STARTED Many nurseries now freezing, and keep the bare-root plants most perennials is in Choosing offer perennials as packing material directly in the the spring because first-year seedlings in slightly moist. If the ground, if it’s work- the plants will estab- Perennials plastic “cell packs.” holding temperature able, in the corner of lish a good root sys- These plants might is not below 50°F, a garden or small tem before winter. take an extra year to watch the plants nursery. A light, This will also reduce establish, but the cost closely because they sandy, well drained the possibility of Perennials are avail- per plant is consider- may yellow and dete- soil is desirable. heaving, a common able in many forms: ably less. riorate if they are Cover plants with problem with poorly as seeds, as dormant kept longer than one slitted row covers or established perennials Try to choose only bare-root plants, in to two weeks. Wrap similar plant protec- in northern climates. fresh, green plants seedling packs like the plants loosely in tors until the danger You can also plant that are bushy and annuals, in 4- and plastic and keep in a of hard frost has new divisions in late compact. If plants 6-inch pots, and in refrigerator if you passed. Be sure the summer, but be sure have flowers, remove 1-gallon containers. have room. If not protectors are venti- the roots have at least them at planting Larger plants repre- carefully protected lated, or remove a month to develop time. sent a considerably from desiccation, the them on sunny or before cold weather larger investment Mail-order businesses plants will deteriorate warm days. Then sets in. A few peren- than their smaller generally wait to ship very quickly. move plants to their nials are at their best counterparts. dormant plants until permanent location. when planted in Another way to han- However, they will the weather is suit- Or, if small, allow August: bearded iris, dle newly purchased produce a full look able for planting. them to grow for a Oriental poppy, bare-root plants is to sooner and you may However, many of year before trans- peony and many pot them in contain- see each plant’s these companies planting. woodland wildflowers and grow them in foliage and possibly operate in southern ers. Potted perennials a protected area, a Many perennials are flowers before you states and plants can be planted any coldframe, a cool relatively trouble-free purchase it. Although sometimes arrive time during the grow- greenhouse or similar and grow best in a more wildflowers and when snow is still on ing season. structure until you loose, moderately fer- ferns are becoming the ground in the can safely plant them tile loam with ade- available, you usually north. In such cases, in their permanent quate moisture. The have to obtain the store dormant plants location. Or plant best time to plant more unusual ones in a cool, dark loca- from specialized tion where the tem- nurseries. perature stays above

11 medium, either scat- and move the con- Fertilizing lowing spring. Be sure Growing tered (broadcast) or tainers to a cooler to watch for mice and in rows, and cover location (60 to 65°F) Seedlings rabbits. Perennials them with the recom- in bright light to Fertilize the plants as mended amount of harden seedlings. soon as the leaves growing medium expand, using a com- from Seed You can also start (usually about two to plete fertilizer such as Transplant- seeds in outdoor three times the diam- 20-10-20 at the rec- seedbeds either in an Many perennials can eter of the seed). ommended rate and ing to the easily be grown from open or a protected frequency listed on seeds, such as Label the containers area, such as a cold- the product label. If Garden columbine, delphini- and water very care- frame. The seedbed the frequency is listed um and rudbeckia. fully to avoid wash- should have porous, as once a month, you ing away the seeds. well drained soil that The best time to Use small pots or should probably fer- Use a fog-type nozzle you have prepared tilize more frequently transplant young trays containing cell or let the containers thoroughly, leveled, plants, whether packs to start seeds. at reduced rates, e.g., stand in a shallow tamped with the back once a week at one- grown from seeds or A standard, well tub of water to avoid of a rake and leveled cuttings, is in early drained growing fourth the monthly disturbing the seeds. again before seeding. rate. Watch for pests, spring after the soil medium works well After preparing the has thawed but the Place the containers such as diseases, for most perennials. bed, sow the seeds plants are still dor- in a warm location insects and mice Seed packets should and cover, following mant. This is usually where the soil tem- (when overwintering include essential directions on the seed 4 to 6 weeks before perature is at least in coldframes). You information, such as packet. Moisten the the average date of 70°F. Cover with plas- may want to use a when to sow, how seedbed with a fog- the last freezing tem- tic to keep the medi- fungicide to help deeply, germination type hose nozzle and perature in the um moist. As soon as control damping-off temperature and be careful not to spring. (See the most of the seeds in addition to using a other information. wash away the seeds. Spring Freeze map, have germinated, sterile growing medi- Sow seeds at the rec- page 32, for average remove the plastic um. ommended rate and times for your loca- time (spring, summer Transplant seedlings tion.) or fall) in a sterile to larger containers (4 to 5 inches) as soon Use stakes to mark as root systems have where the plants will go before you set SOWING SEEDS: COVER & WATER: developed throughout the growing them out. Be sure to medium. Overwinter allow enough space. seedlings of most Dig holes in prepared species in a protected beds using a trowel or location, such as a spading fork. Make coldframe, until final the holes large transplanting the fol- enough so that roots have plenty of room and plant at a depth to accommodate each

STAKING TALL PLANTS:

TRANSPLANTING YOUNG PLANTS:

12 phinium, false indigo Zones 4 to 6, divide MULCHING: and globe thistle. The plants in the spring flowers won’t be as while they are still numerous on the dormant. This avoids regrowth, but cutting subjecting the newly back does result in a divided plants to longer, although not harsh winter temper- continuous, flower- atures and reduces ing period. the chances of heaving. The method of division varies among Propagation types of perennials. In general, vigorous Methods new shoots from the outside of a clump are preferred for replanting, but you can use all shoots, if Dividing desired. Many vigorous peren- To make digging easi- nials crowd them- er, water the bed well selves and require a few days before- root system. Firm the ing spring after the at the time of plant- dividing every few hand if the soil is dry. soil around the roots danger of severe frost ing can provide suffi- years. Also, the most Before dividing, so there are no empty has passed. A winter cient nutrients for aggressive types can prune the plants by spaces between roots mulch can help unre- many years and elim- escape and choke out half if stems are still and soil. Water thor- liably hardy plants inate the need for fer- other plants around present. Dig out the oughly. survive the winter. tilizer. Exceptions are them. Dividing is entire clump. Divide Staking Tall astilbe, chrysanthe- often done in the fall the healthy living mum, delphinium, in warmer areas of portions into smaller Maintenance Plants lupines and summer the country, but in clumps by working You may have to phlox, which should stake tall plants as be fertilized every they grow. Stake each year. If plants are not stem individually vigorous and foliage is light green or yel- DIVIDING PLANTS: Water the perennial instead of trying to tie them all together. lowish, applying a garden when soil nitrogen-based fertil- becomes dry. This Tie the plant to the stake with plastic izer would probably will vary with soil be beneficial. type. Watch new beds strips or wire covered for signs of wilting. with a plastic coating. Weed Control Young, newly planted Make a double loop of the wire with one Cultivate perennials perennials will need as frequently as need- more frequent water- loop around the plant and the other ed to control weeds. ing than mature, Most weeds can be established plants. around the stake. This keeps the stem killed by using an Water thoroughly action hoe or a simi- and try not to splash from rubbing against the stake. For tall, lar tool (see illustra- water on the foliage. tion of tools). Work Use a trowel to check arching plants, make or purchase circular the top half-inch of the soil for mois- the soil. If you culti- ture—soil should be rings and attach them to the stakes to vate much deeper, moist 4 to 5 inches you can injure plant deep. It is better to support plants and to maintain their natu- roots. Frequent, shal- water thoroughly and low cultivation is bet- less frequently than ral form. A three- legged support called ter than occasional, to apply many super- deep cultivation. Try ficial waterings. a peony hoop is less obstructive than not to walk in the Apply a 2-inch layer poles in the garden. beds while weeding. of mulch over the Tomato cages can be Soil can be easily bed or border every used in the same way. compacted, which spring, tapering it off limits root growth. gradually near each Fertilizing Blooming plant. You may apply If desired, apply fertil- a layer of winter izer as growth begins “Dead-head”—that is, mulch 4 inches deep in the spring. Because remove old flower after the soil is frozen many soils have ade- heads—after bloom- to a depth of 2 inch- quate phosphorus ing unless the fruits es. This helps prevent and potassium but are ornamental. This winter injury, espe- are deficient in nitro- prolongs the flower- cially heaving. If you gen, use a complete ing period of many apply mulch too fertilizer every 3 or 4 perennials, especially early, rodent prob- years and supplement dianthus, coreopsis lems may develop. it with a nitrogen- and shasta daisy. Use an open, fluffy based fertilizer other A few species will material, such as pine years. However, most bloom a second time boughs, pine needles perennials are not if the stems are cut or excelsior over the heavy feeders. back after flowering. entire bed. Remove Organic matter added Examples are del- this layer the follow-

13 OTHER METHODS OF PROPAGATION

Propagation by stem cuttings: Dendranthema grandiflora (Garden mum)

Propagation by rhizome division: Iris (Bearden iris)

Propagation by root cuttings: Phlox paniculata (Garden phlox)

Propagation by crown division: Dicentra spectabillis (Old-fashioned bleeding heart)

14 them apart with your fingers or making small cuts with a knife. Divide large, CONTROLLING DISEASES dense clumps using two spading forks back-to-back. In general, replace one or AND PESTS two healthy divisions in the original hole and plant the others Three types of pesti- Leaf blotch can be elsewhere. Prevention cides are used on caused by other fungi Insects perennials: fungicides as well. Brown spots Some species have for diseases, insecti- are a common prob- large taproots and cides for insects and lem on peony, iris should not be divided miticides for spider and mum. or moved unnecessar- mites. These are usu- The most common Although most peren- Root rots (fungus, ily. Examples are ally applied as dusts insects that attack nials have few major bacteria) can be seri- baby’s-breath, bal- or sprays. Some come perennials are aphids, disease or insect prob- ous problems for loon flower, butterfly ready to use. beetles, caterpillars, lems, several pests perennials in moist weed and lupine. leafhoppers, spider can attack them. soil. The best solution mites, thrips and, Other These pests vary in is to improve soil occasionally, tar- type and severity drainage, especially Propagation Diseases nished plant bugs. from area to area and over winter, or move Methods year to year. You can the plant to a more Aphids are small, There are several control most of them suitable location. sucking insects that other ways to propa- effectively if you fol- are concentrated at Powdery mildew gate perennials. You low these general rec- Of the many diseases the tips of young (fungus) covers leaves can propagate ommendations: that attack perenni- shoots, on stems and with a whitish sub- chrysanthemums by als, aster yellows, on the undersides of • Buy plants that are stance. Avoid over- stem and root cut- botrytis blight, pow- leaves. free of diseases and crowding and plant- tings; iris by rhizome dery mildew and rust insects. ing in wet or shady Beetles feed on pieces; anemone and are the most serious. perennial phlox by • Buy disease-resis- locations. It often leaves, stems and root cuttings; and tant species when Aster yellows occurs on monarda, flowers. (mycoplasma) causes phlox and delphini- peonies and bleeding- available. Caterpillars usually the yellowing of leaf um. heart by taking roots feed on leaves. • Keep your garden tips and flowers, also with one or more Rust (fungus) causes free of weeds, fallen stunting of the plant Leafhoppers are “eyes.” Consult other reddish brown spot- leaves, and diseased and abnormal small, leaping insects gardeners, catalogs or ting on leaves, young or insect-infested growth. Leafhopper that feed on many books for more stems and flower plants. insects carry this dis- kinds of plants by details on specific parts. Rust is com- ease from plant to sucking sap. methods. • Remove seriously mon on hollyhocks. plant. Asters, mums, diseased or insect- Spider mites are very statice and some oth- infested plants as tiny pests that feed ers can get aster yel- soon as you notice on leaves and stems. lows. them. Look for fine webs to • Apply fungicides The only cure is to indicate their pres- and insecticides only remove the infected ence. They are usual- as needed. plants and to control ly located on the leafhoppers. undersides of leaves. If a serious problem Mites thrive in hot, Botrytis blight (fun- develops, consult dry weather. They are gus) is a gray mold your local garden very difficult to see that attacks leaves, center or Cooperative without a magnifying stems and flowers. Extension office for glass (look for move- Most flower petals are the best control ment). Shaking the susceptible, especially methods. Select natu- leaves over a white peony flowers in wet ral or processed pesti- paper is another way weather and shasta cides by studying the of determining their daisy in late summer information below presence. and on pesticide con- during times of heavy tainer labels. Follow dew. Thrips are very small label directions for insects, sometimes dilution and care in with wings, that suck handling. sap. Leaves may be finely mottled. Thrips will attack growing points and flowers.

15 BOOKS FOR FURTHER READING

Armitage, Allan M. Giles, F.A. Keith, Sinnes, A. Cort, and Herbaceous Rebecca McIntosh Michael D. McKinley. Additional Information Perennial Plants. and All About Athens, Ga.: Varsity Donald C. Saupe. Perennials. Press, 1989. Herbaceous San Francisco, Calif.: Many publications For more informa- Perennials. Ortho Books, are available on tion, contact: Billington, Cecil. Reston, Va.: Reston Chevron Chemical Ferns of Michigan. perennials, wild- American Publishing Company, Company, 1981. flowers, ferns and Cranbrook Institute 1980. Horticultural of Science Bulletin Smith, Helen V. related topics, and a Society No. 32. Bloomfield Harper, Pamela, and Michigan few are listed. Several Box 105 Hills, Mich.: The Frederick McGourty. Wildflowers. gardening magazines Mount Vernon, Cranbrook Press, Perennials: How to Cranbrook Institute include articles on VA 22121 1952. Select, Grow and of Science Bulletin perennials, often on Enjoy. 42, Bloomfield Hills, specific kinds or The A.H.S. has a list Bloom, Alan. Tucson, Ariz.: HP Mich.: The species. Nursery cata- of plant societies and Perennials for Your Books, Inc., 1985. Cranbrook Press, logs and libraries are national horticultural Garden. 1961. additional sources of organizations. Chicago, Ill.: Hudak, Joseph. information. Perennial Plant Floraprint USA, 1981. Gardening with Snyder, Leon C. Association Perennials. Native Plants for Many gardeners spe- Bloom, Alan. cialize in growing one Room 217 Beaverton, Ore.: Northern Gardens. Howlett Hall Alpines for Your Timber Press, 1985. Chanhassen, Minn.: or more species of Garden. perennials, and there 2001 Fyffe Court Andersen Columbus, OH 43210 Chicago, Ill.: Loewer, H. Peter. Horticultural Library are even organiza- Floraprint USA, 1981. Growing and Press, 1991. tions devoted to Membership is limit- Decorating with perennials or certain ed to nursery people Clausen, Ruth R., and Grasses. Still, Steven. groups of plants, such and professional hor- Nicolas H. Ekstrom. New York, N.Y.: Herbaceous as chrysanthemums, ticulturists. Perennials for Walker and Ornamental Plants. daylilies, delphini- American Gardens. Company, 1977. Champaign, Ill.: ums, hostas, penste- Andersen New York: Random Stipes Publishing mons, irises, peonies, Horticultural House, 1989. Meyer, Mary Company, 1982. primroses, ferns, Library Hockenberry. herbs, rock gardens Minnesota Landscape Cox, Jeff, and Ornamental Thomas, Graham and wildflowers. Arboretum Marilyn Cox. Grasses— Stuart. 3675 Arboretum The Perennial Decorative Plants Perennial Garden Drive Garden. for Home and Plants. Chanhassen, Emmaus, Pa.: Rodale Garden. England: J.M. Dent, MN 55317 Press, 1985. New York, N.Y.: 1981. 612/443-2440 Drew, John K. Charles Scribner’s Sons, 1975. Wilson, Jim. The Source List of Pictorial Guide to Landscaping with Plants and Seeds, Hardy Perennials. Phillips, Harry R. Wildflowers. compiled by the Kalamazoo, Mich.: Growing and Boston: Houghton library, lists nurseries Merchants Publishing Propagating Wild Mifflin, 1992. carrying specific culti- Co., 1984. Flowers. vars of many perenni- Chapel Hill, N.C.: als. University of North Carolina Press, 1985.

16 PERENNIALS WITH SPECIAL FEATURES

Monarda didyma SHORTER TALLER Oenothera missouriensis • PERENNIALS PERENNIALS Physostegia virginiana • indicates perennials that are good for rock Achillea X ‘Coronation Gold’, 4-5 feet Primula spp. gardens Aconitum spp., 3-5 feet Rudbeckia fulgida • Aegopodium podagraria, 12 inches Anemone X hybrida, 2-4 feet Salvia spp. • Ajuga spp., 6 inches Anthemis tinctoria, 2 feet Saponaria ocymoides • Aquilegia spp., 12-36 inches Aruncus dioicus, 5 feet Thalictrum Arabis albida, 12-18 inches; spreading • Asclepias tuberosa, 2-3 feet Tradescantia X andersoniana Armeria maritima, 6 inches • Aster novae-angliae, 2-5 feet Trollius hybrids Artemisia schmidtiana, 12-36 inches Baptisia australis, 3-4 feet Aster alpinus, 6-12 inches • Belamcanda chinensis, 3 feet Astilbe X arendsii, 12-24 inches; mound Calamagrostis X acutiflora, 4-6 feet PERENNIALS Aubretia deltoidea, 6 inches • Centaurea montana, 2-3 feet Aurinia saxatilis, 6-12 inches • Centranthus ruber, 2-3 feet FOR SHADY SITES • indicates drought tolerant Bergenia cordifolia, 12-18 inches Delphinium X elatum, 2 1/2-5 feet Astilbe X arendsii • Brunnera macrophylla, 12-18 inches Dendranthema grandiflora, 2-4 feet Bergenia cordifolia • Campanula carpatica, 12 inches • Dicentra spectabilis, 2-3 feet Brunnera macrophylla • Cerastium tomentosum, 6-12 inches • Dictamnus albus, 3 feet Convallaria majalis Ceratostigma plumbaginoides, 6 inches Echinacea purpurea, 3-5 feet Dicentra spp. Convallaria majalis, 6-12 inches Echinops ritro, 3-4 feet Geranium spp. • Dianthus spp., 6-18 inches • Eupatorium coelestinum, 2 feet Hemerocallis Dicentra eximia, 12-18 inches Geum quellyon, 2-2 1/2 feet Heuchera sanguinea Doronicum caucasicum, 12 inches; mound Helenium autumnale, 3-5 feet Hosta Epimedium spp., 9 inches • Helianthus X multiflorus, 3-5 feet Iris sibirica Euphorbia epithymoides, 12-13 inches • Heliopsis helianthoides, 3-4 feet Mertensia virginica • Festuca cinerea, 12 inches; mound Hemerocallis, 1 1/2-4 feet Myosotis spp. Gaillardia X grandiflora, 6-24 inches Hibiscus moscheutos, 5-8 feet Polygonatum spp. • Galium odoratum, 6 inches Iris hybrids, 2-3 feet Primula spp. Geranium spp., 6-18 inches • Iris sibirica, 2-4 feet Thalictrum spp. Helleborus spp., 12-18 inches Liatris spp., 2-5 feet Trollius hybrids Heuchera sanguinea, 12-30 inches Ligularia spp., 3-6 feet Viola spp. Hosta, 12-48 inches Limonium latifolium, 2 feet Iberis sempervirens, 6-12 inches • Linum perenne, 2 feet Incarvillea delavayi, 12-18 inches Lobelia cardinalis, 2-3 feet PERENNIALS FOR Iris hybrids, 4-15 inches • Lupinus hybrids, 3-4 feet Lamiastrum galeobdolon, 6-18 inches Lysimachia punctata, 3 feet HOT, DRY SITES Lamium maculatum, 6 inches Miscanthus sinensis, 4-6 feet Achillea spp. Lavandula angustifolia, 12-36 inches Monarda didyma, 2 1/2-3 feet Anthemis tinctoria Leontopodium alpinum, 6 inches • Paeonia hybrids, 2-3 feet Arabis albida Leucanthemum X superbum, 12-48 inches Papaver orientale, 3-4 feet Armeria maritima Liriope spicata, 12 inches Pennisetum alopecuroides, 3-6 feet Artemisia spp. Myosotis spp., 12 inches; trailing Phlox paniculata hybrids, 2-4 feet Asclepias tuberosa Nepeta X faassenii, 12-18 inches Physostegia virginiana, 2-4 feet Aurinia saxatilis Oenothera missouriensis, 12 inches; Rodgersia spp., 3-4 feet Baptisia australis spreading Rudbeckia fulgida, 2-3 feet Centaurea montana Opuntia humifusa, 6 inches Sidalcea malvaeflora, 3 feet Coreopsis spp. Penstemon spp., 6-30 inches Thalictrum spp., 3-6 feet Dianthus deltoides Phlox subulata, 3-6 inches • Yucca filamentosa, 4-6 feet Echinops ritro Polygonatum spp., 12-36 inches Euphorbia epithymoides Polygonum affine, 12 inches; spreading Gaillardia X grandiflora Potentilla spp., 6-12 inches • Gypsophila paniculata Primula spp., 6-12 inches • PERENNIALS FOR MOIST Hemerocallis Prunella X webbiana, 12 inches; spreading Lavandula angustifolia Pulmonaria saccharata, 12-24 inches; TO WET SITES Liatris spp. spreading • indicates tolerant of clay or heavy soils Lychnis chalcedonica Salvia spp., 12-36 inches Aster novae-angliae • Oenothera missouriensis Saponaria ocymoides, 8 inches • Astilbe X arendsii • Penstemon spp. Scabiosa caucasica, 12-18 inches Euphorbia epithymoides • Rudbeckia fulgida Sedum spp., 3-12 inches • Heliopsis helianthoides • Salvia spp. Sempervivum spp., 6 inches • Hibiscus moscheutos Saponaria ocymoides Stokesia laevis, 12-18 inches Hosta • Sedum spp. Thymus spp., 3-12 inches Iris sibirica Veronica spp. Veronica spp., 6-30 inches • Lobelia cardinalis Viola spp., 12 inches; mound Mertensia virginica

17 PERENNIALS WITH SPECIAL FEATURES NATIVE NORTH PERENNIALS FOR CUT PERENNIALS FOR AMERICAN PERENNIALS FLOWERS NATURALIZING Achillea millefolium • indicates also good for dried arrangements Achillea millefolium Aquilegia canadensis Achillea spp. • Ajuga spp. Artemisia ludoviciana Anemone X hybrida Aquilegia spp. Aruncus dioicus Anthemis tinctoria Asclepias tuberosa Asclepias tuberosa Artemisia ludoviciana • Baptisia australis Aster novae-angliae Aster spp. Cerastium tomentosum Aster novi-belgii Astilbe X arendsii • Convallaria majalis Baptisia australis Centaurea montana • Coreopsis lanceolata Chelone spp. Convallaria majalis • Dicentra spp. Coreopsis spp. Coreopsis spp. • Echinacea purpurea Dicentra eximia Delphinium X elatum • Heliopsis helianthoides Echinacea purpurea Dendranthema grandiflora Hemerocallis Erigeron speciosus Dianthus spp. Hosta Geranium maculatum Echinacea purpurea • Liatris spp. Helenium autumnale Echinops ritro • Lobelia cardinalis Heliopsis helianthoides Gypsophila paniculata • Monarda didyma Hibiscus moscheutos Helianthus X multiflorus Phlox subulata Liatris spp. Heliopsis helianthoides Physostegia virginiana Lobelia cardinalis Hemerocallis Rudbeckia fulgida Mertensia virginica Heuchera sanguinea • Tradescantia X andersoniana Monarda didyma Hosta Veronica spp. Oenothera tetragona Iris Viola spp. Oenothera missouriensis Leucanthemum X superbum Opuntia humifusa Liatris spp. Penstemon spp. Lupinus hybrids LOW MAINTENANCE Phlox spp. Lychnis chalcedonica • Polygonatum commutatum Miscanthus sinensis • PERENNIALS Achillea X ‘Coronation Gold’ Polygonatum biflorum Monarda didyma Asclepias tuberosa Potentilla tridentata Paeonia hybrids Bergenia cordifolia Rudbeckia spp. Papaver orientale • Brunnera macrophylla Viola cucullata Pennisetum alopecuroides • Calamagrostis acutiflora Viola pubescens Penstemon spp. Campanula spp. Phlox paniculata hybrids Coreopsis verticillata Physostegia virginiana Dicentra spectabilis PERENNIALS WITH Pyrethrum roseum Echinacea purpurea Rudbeckia fulgida • Echinops ritro FRAGRANT FLOWERS Salvia spp. Heliopsis helianthoides Sedum ‘Autumn Joy’ • OR FOLIAGE Hemerocallis spp. Trollius hybrids Artemisia spp. Hosta spp. Veronica spp. Convallaria majalis Iris sibirica Viola spp. • Dianthus X allwoodii Liatris spp. Echinacea purpurea Limonium latifolium Hemerocallis Paeonia hybrids Hosta Papaver orientale Lavandula angustifolia Platycodon grandiflorus Monarda didyma Sedum `Autumn Joy’ Paeonia lactiflora Phlox paniculata hybrids Salvia spp. ORNAMENTAL Thalictrum spp. Thymus spp. GRASSES Viola spp. Calamagrostis acutiflora Festuca cinerea Miscanthus sinensis Pennisetum alopecuroides

18 SELECTING PERENNIALS Names Height Light Level Guide Each perennial has a The height of peren- single, specific botan- nials varies consider- Level Location Amount of sun or shade ical name that ably from species to Sun Open beds, south- or west- No more than 3 hours of shade includes a genus, species, and from one facing beds which is capitalized, particular environ- followed by a species, ment to the next. Part shade East-facing beds At least 6 hours of full sun which is written in Also, many dwarf cul- Shade North-facing beds, Essentially no full sun lowercase letters. tivars are available. woodlands Perennials may have Plants will often be one or several differ- taller in shade or in ent common names rich soil. The guide areas of the region. Hardiness can often Special Notes that differ from one gives the common For plants grown for be improved by region to another. range for plants in foliage, such as some planting in well This category Frequently, the genus flower. Foliage height ornamental grasses, drained soil and includes miscella- is used as a common may be much less. this is the period of using a winter mulch. neous care instruc- name, such as del- significant ornamen- tions, suggestions for phinium, hosta or Spread tal value. Division/ use and special features, as well as unde- iris. When many It is necessary to Light Propagation sirable characteristics. species within a sin- allow sufficient room The recommen- Most perennials pre- Plants that self-seed gle genus are being for perennials to dations given are fer full sun to light may be propagated discussed, the abbre- develop properly. based on needs for shade. Some tolerate by transplanting viation “spp.” follows Spread tells you the rejuvenating plants different light levels, seedlings. However, the genus. mature spacing rec- and controlling size, and a few require the new plants may ommended between not simply propaga- To help you use the either full sun or deep not be true to type. the center of one tion. The best time of tables in this bulletin shade. The guide plant and the center year to divide a par- and order perennial indicates the opti- of the next. For a ticular plant is given, stock, a cross-refer- mum light level or complete look sooner, as well as an average ence index is includ- range of light levels plant closer together of how frequently it ed at the back of this for each plant. Three and remove extra should be divided. A bulletin (p. 29) that light levels are used: plants before crowd- blank in this column lists common names sun, part shade and ing occurs. indicates that the spe- followed by botanical shade. names. Bloom Period cific plant does not Hardiness need to be divided Colors The time and dura- except for propagation of flowering for a The number listed in tion. “No” indicates These include cur- the table indicates rently available flow- given perennial is that the plant should important to consider the minimum hardi- not normally be er colors. New culti- ness zone (see hardi- vars are released when designing a gar- divided. den. Actual dates of ness zone map on every year that will page 32) recommend- add to this list. Many bloom can vary up to 3 weeks from year to ed for growing a par- seed and nursery cat- ticular plant. It is alogs indicate the lat- year, depending on the weather. Regional based on the USDA est selections avail- map of climate zones. able. For plants climatic conditions, location of the gar- Average annual mini- grown primarily for mum air tempera- foliage, the selection den and proximity to large lakes can also tures for Zone 3 are: and care guide lists -40°F to -30°F; foliage color. influence this timing. The dates given are Zone 4: -30°F to for the central part of -20°F; Zone 5: -20°F the north central to -10°F; Zone 6: region (Detroit, -10°F to 0°F. Chicago, Dubuque). This system is only These dates will vary an approximate indi- by at least 1 month cation because it is earlier farther south based on minimum or 1 month later in air temperatures and the northernmost not on soil temperatures belowground where most perennials overwinter.

19 PERENNIAL SELECTION AND CARE GUIDE Mature Division Other Flowering spread and (time of year; Special notes Botanical name common height form Bloom Hardiness frequency in (cultural uses, (Common name) name(s) Color (feet) (inches) period Light (zone) years) major pests, etc.) Achillea X ‘Coronation Gold’ Fern-leaf yarrow Yellow 2-4 36; mound Mid-June- Sun 3-9 Spring; 3-4 Dead-head to (‘Coronation Gold’ yarrow) October prolong flowering. Aromatic foliage. Excellent dried flower. Achillea millefolium and hybrids Pink, white, 1 1/2-3 24; spreading Late June- Sun 3-9 Spring; 2-3 Can be invasive. (Common yarrow) red, yellow, mound September Dead-head to salmon prolong flowering. North American native. Aconitum spp. Aconite Blue, yellow 3-5 12-24; August- Sun to 3-7 No All parts of the (Monkshood) Wolfsbane mound October part shade plant are poisonous. Grows well in moist soil. Needs cool nights. Aegopodium podagraria Bishop’s weed Green or 1 12; May-June Any 3-10 Any Green form often (Goutweed) variegated mound invasive. Variegated foliage form is not as invasive. Commonly used as a ground cover in areas where it can be kept from spreading. Ajuga spp. Carpet bugle Blue, purple, 1/2-1 9-24; April-June Any 3-9 Any Cultivars are (Bugleweed) white spreading available that have variegated or purple foliage. Commonly used as a ground cover. Can be invasive. Anemone X hybrida, A. vitifolia, Japanese anemone Pink, white 2-4 18-24; August- Sun to 4-8 Will not grow well A. hupehensis mound October part shade in areas with dry (Windflower) summers or wet winters. Protect from wind; mulch in winter. Has attractive seedheads. Syn. A. japonica. Anthemis tinctoria Yellow chamomile Yellow, white 2 18-24; June- Sun 3-7 Spring; 2 Prune back in late (Golden Marguerite) mound September summer; self-seeds. Foliage is fragrant. Dead-head to prolong flowers. Aquilegia spp. All colors 1-3 12; May-July Sun to 3-9 No Is short-lived but (Columbine) mound part shade self-seeds. Dead- head to prolong flowering. Subject to leaf miner. Grows best in moist soils. Some are North American natives. Arabis albida Wall cress Pink, white 1/2 12-18; April-June Sun to 4-7 Ground cover. (Rock cress) spreading part shade Prune back to 3 inches after flowering. Needs good drainage. Armeria maritima Sea thrift Pink, red, 1/2-1 6-12; May-June Sun 4-8 Grows best in sandy (Thrift) Sea pink white spreading soil. Clumps tend to rot in moist or heavy soils. Tolerates salt. Artemisia ludoviciana Silver foliage 2-4 24; Silver foliage Sun 4-9 Excellent dried (Silver king, silver queen) mound May-October flower. North American native. Artemisia schmidtiana Wormwood Silver foliage 1-2 18; Silver foliage Sun 3-7 Spring; 3 Grown only for its (‘Silver Mound’ artemisia) mound May-October foliage, which is also fragrant. Soil must be well drained. Do not fertilize. Cut back each season. Aruncus dioicus White 5 36-60; June-July Part shade 2-7 Prefers moist soil. (Goat’s-beard) mound to shade North American native. Asclepias tuberosa Orange 2-3 12; June-August Sun 3-9 No Tolerates poor, (Butterfly weed) mound sandy, dry soil. Stems emerge slowly in spring. Attracts butterflies. Has attractive seed pods. North American native. Aster alpinus Purple, blue, 1/2-1 24; May-June Sun 4-7 Short-lived. Needs (Alpine aster) pink mound well drained soil.

20 PERENNIAL SELECTION AND CARE GUIDE Mature Division Other Flowering spread and (time of year; Special notes Botanical name common height form Bloom Hardiness frequency in (cultural uses, (Common name) name(s) Color (feet) (inches) period Light (zone) years) major pests, etc.) Aster novae-angliae, Michaelmas daisy Blue, pink, 2-5 24-48; September- Sun 4-8 Spring; 2 Grows best in rich, Aster novi-belgii New England aster purple, red, mound October well drained soil. (Hardy aster) white Pinch back in late spring. Aster yellows and powdery mildew are common problems. North American native. Astilbe X arendsii False spirea Pink, red, 2-4 12-24; June- Shade 4-9 Spring; 3 Grows best in deep, (Astilbe) white mound August fertile soil high in organic matter. Protect from wind. Aubrieta deltoidea Purple 1/2 18-24; April-June Sun to 4-8 Ground cover. Trim (Purple rock cress) spreading part shade back halfway after flowering. Prefers well drained soil. Aurinia saxatilis Goldentuft alyssum Yellow 1/2-1 12; May Sun to 3-7 No Long-lived. Trailing (Basket-of-gold) trailing part shade habit. Syn. Alyssum saxatile. Baptisia australis Wild indigo Blue 3-4 24-48; May-June Sun to 3-9 Self-seeds. Pods are (False indigo) mound part shade attractive. North American native. Belamcanda chinensis Orange 3-4 12-24; July- Sun 5-10 Spring; 2 Self-seeds. Iris borer (Blackberry lily) upright September can be a problem. Clusters of black seeds are attractive. Bergenia cordifolia Pink, white, 1-1 1/2 12; May Part shade 3-8 Spring; 4 Slugs can be a (Bergenia) red basal to shade problem. Foliage leaves often damaged by winter or spring frost or drought. Brunnera macrophylla Blue 1-1 1/2 12-18; April-June Part shade 3-7 Self-seeds and can (Siberian forget-me-not) spreading to shade be invasive. Tolerates dry soil and tree roots. Calamagrostis acutiflora Golden 4-6 36; June-frost Sun to 4-9 Non-spreading (Feather reed grass) seedheads vertical part shade ornamental grass. Very easy but very showy. Needs no staking. Campanula carpatica Bluebells Blue, white 1 12; June- Sun 3-8 Needs good (Carpathian harebell) basal leaves August drainage. Campanula glomerata Bluebells Blue, white, 1-2 12-18; June- Sun to 3-8 May need staking. (Clustered bellflower) violet mound September part shade Brilliant massed flowers. Centaurea macrocephala Yellow 3-4 24; July Sun 3-7 Basal leaves. (Golden century) upright Excellent cut flower. Centaurea montana Blue, white, 2 12; June- Sun 3-8 Spring; 2 Cut back after (Mountain bluet) pink mound September flowering. Centranthus ruber Jupiter’s-beard Pink, white 2-3 24; May-August Sun to 4-8 Spring; 3 Tolerates poor soil. (Red valerian) mound part shade Self-seeds easily. Cerastium tomentosum White 1/2 18-24; May-June Sun 2-7 Spring; 2 Trim back after (Snow-in-summer) spreading flowering. Silver foliage. Can be invasive. Dies back in hot weather. Ceratostigma plumbaginoides Blue 1/2-1 12-18; July- Sun to 5-9 Spring; 3 Mulch in winter. (Leadwort) spreading September part shade Shoots emerge late. Chelone spp. Pink, white 2-3 12-24; August- Sun to 3-8 Tolerates moist soil. (Turtlehead) mound October part shade North American native. Chrysogonum virginianum Goldenstar Yellow 1/2-1 24; April- Any 5-9 Spring; 4 Ground cover. (Green-and-gold) spreading September Prefers moist soil. Convallaria majalis White, pink 1/2-1 6; dense May-June Part shade 2-7 Flowers are fragrant. (Lily-of-the-valley) clump to shade Berries are poisonous. May be invasive. Coreopsis grandiflora, C. lanceolata Butter daisy Yellow 1 1/2-3 12; June- Sun 3-9 Spring; 2-3 Dead-head to (Lance-leaf coreopsis) Tickseed mound October prolong bloom period. Powdery mildew can be a serious problem. North American native. Coreopsis verticillata Yellow 1 1/2-3 24; July- Sun 3-9 Doesn’t need dead- (Thread-leaf coreopsis) mound October heading. North American native.

21 PERENNIAL SELECTION AND CARE GUIDE

Mature Division Other Flowering spread and (time of year; Special notes Botanical name common height form Bloom Hardiness frequency in (cultural uses, (Common name) name(s) Color (feet) (inches) period Light (zone) years) major pests, etc.) Dendranthema grandiflora Hardy All colors 1-4 12-36; August- Sun 4-9 Spring; 2-3 Aphids, aster (Mum) chrysanthemum except blue mound or October yellows, powdery spreading mildew and rust are common problems. Heavy feeder; grows best in well drained soil with high organic matter. Plants can be moved in full bloom. Syn. Chrysan- themum X morifolium. Dianthus X allwoodii Grass pink Pink, red, 1/2-1 1/2 12-15; June- Sun 4-8 Spring; 3-4 Grows best in a (Cottage pinks) Pink salmon, basal August fertile, well drained, Hardy carnation white slightly alkaline soil. Flowers are fragrant. Some will reseed. Prune lightly after flowers fade. Some are short-lived. Dianthus deltoides Pinks Pink, red, 1/2-1 24; June Sun 3-9 Needs good (Maiden pink) white mat drainage. Dicentra eximia Wild bleeding-heart Pink, red, 1-1 1/2 12; May-July Part shade 3-9 Grows best in a rich, (Fringed bleeding-heart) white mound well drained soil kept moist in the summer. Mulching is desirable. North American native. Dicentra spectabilis Pink, white 2 24; May-June Part shade 2-9 Spring or Grows best in a rich, (Bleeding-heart) arching to shade late summer well drained soil stems kept moist in the summer with mulching. Goes dormant in summer. Dictamnus albus Pink, white 3-4 24; May-June Sun 3-8 No Touching any part of (Gas plant) vertical the plant may result in dermatitis. Fragrant foliage. Slow growing. Syn. D. fraxinella. Doronicum caucasicum Yellow 1-1 1/2 12; April-May Sun to 4-7 May go dormant in (Leopard’s-bane) mound part shade summer. Syn. D. cordatum. Echinacea purpurea Pink, white 3-5 18-24; July- Sun to 3-8 Spring; 3-4 Grows best in well (Purple coneflower) mound September part shade drained soil. Fragrant flowers. Excellent cut flower. North American native. Echinops ritro Blue 3-4 24; July- Sun 3-8 Spring; 3-4 Tolerates dry soil. (Globe thistle) mound October Attracts bees. Epimedium spp. Pink, white, 1/2-1 12; May Part shade 3-8 Ground cover. (Barrenwort) yellow, red spreading to shade Tolerates competition from tree roots. Erigeron speciosus Purple, pink 1 1/2- 12; June- Sun 2-8 Spring; 2-3 Dead-head to (Daisy fleabane) 2 1/2 mound November prolong flowering. North American native. Eupatorium maculatum, Purple, 4-7 36; September Sun to 2-8 Needs moist soil. E. purpureum white, pink upright part shade Fragrant leaves. (Joe-pye weed) North American native. Eupatorium coelestinum Hardy ageratum Blue, white 2 12-24; September- Any 5-9 Spring; 3 Stems emerge slowly (Mist flower) mound October in late spring; spreading. Euphorbia epithymoides Chartreuse 1-1 1/2 12-18; April-May Sun 4-8 Long-lived. Milky sap (Cushion spurge) yellow mound may irritate skin. Syn. E. polychroma. Festuca cinerea Silver-blue 1 (foliage) 12; April-October Sun 4-10 Ornamental grass. (Blue fescue) foliage mound (foliage) Gaillardia X grandiflora Solid or 1/2-3 24; June- Sun 2-10 Spring; 1 Short-lived. Aster (Blanket flower) bicolor red mound September yellows and powdery and yellow mildew are problems. Requires well drained soil. Galium odoratum White 1/2 12; May-June Part shade 4-8 Ground cover. (Sweet woodruff) spreading to shade Prefers moist soils. Has fragrant foliage. Syn. Asperula odorata.

22 PERENNIAL SELECTION AND CARE GUIDE Mature Division Other Flowering spread and (time of year; Special notes Botanical name common height form Bloom Hardiness frequency in (cultural uses, (Common name) name(s) Color (feet) (inches) period Light (zone) years) major pests, etc.) Geranium spp. Cranesbill Blue, pink, 1/2-1 1/2 12-24; April- Sun to 3-8 Spring; 2-4 Tolerates alkaline (Hardy geranium) purple, red, mound August part shade soil. Prefers moist white soil. Some are North American natives. Geum quellyon Orange, red, 2-2 1/2 12-18; May- Sun 5-7 Soil should be rich in (Avens) yellow basal September organic matter leaves and well drained. Short-lived. Mulch to overwinter. Goniolimon tartaricum White 1 1/2 24; July Sun 4-9 No Excellent dried (German statice) mound flower. Gypsophila paniculata Pink, white 2-3 24-36; June-frost Sun 3-9 No Grows best in a well (Baby’s-breath) mound drained, alkaline soil (pH 6.8-7.5). Excellent cut or dried flower. Helenium autumnale Orange, 3-5 18; August- Sun 3-8 Spring; 3 Tolerates wet soils. (Sneezeweed) yellow mound October Do not fertilize. North American native. Helianthus X multiflorus Yellow 3-5 24; August- Sun 4-8 Spring; 2 May require staking. (Perennial sunflower) upright October Does not set seed. Heliopsis helianthoides Perennial sunflower Orange, 3-4 24-48; July- Sun 3-9 Spring; 2 Long-lived. North (Heliopsis) Oxeye yellow upright October American native. mound Excellent cut or dried flower. Helleborus niger, H. orientalis Christmas rose Green, pink, 1-1 1/2 12; March-May Part shade 4-9 Grows best in rich (Hellebore) Lenten rose white mound to shade soils that are consistently moist. Hemerocallis spp. and cultivars Orange, 1 1/2-4 18-36; June- Sun to 3-9 Very easy to grow (Daylily) pink, red, upright September part shade and trouble-free. yellow, clump Newer cultivars lavender, spread less and cream flower more. Heuchera sanguinea Pink, red, 1-2 12; arching May-August Part shade 3-8 Spring; 3 Grows best in well (Coralbells) white stems to shade drained, moist soil. Mulch to reduce heaving during winter. Hibiscus moscheutos Pink, red, 5-8 24-30; July-August Sun 4-9 A large, shrubby, (Rose mallow) white mound coarse-textured plant. Has very large flowers. North American native. Hosta spp. and cultivars Plantain lily Purple, 1-4 30-36; June- Part shade 3-9 Unneeded Full sun may scorch (Hosta) Funkia white mound September to shade leaves. Grows best in moist soil. Grown for variegated foliage—white, yellow, blue, green. Has fragrant flowers. Iberis sempervirens Evergreen candytuft White 1/2-1 12-18; April-June Sun to 3-9 No Leaves are (Candytuft) mound part shade evergreen. Self- seeds but may not be true to variety. Propagate by cuttings. Incarvillea delavayi Pink 1-1 1/2 12-18; April-June Sun to 5-7 Avoid Mulch in winter. (Hardy gloxinia) mound part shade Slow to emerge. Iris kaempferi Blue, pink, 2-3 18-24; Late June- Sun to 4-9 Late summer; 3 Iris borer is a com- (Japanese iris) purple, white vertical July part shade mon pest. Needs moist, slightly acid soil. Cut back to 6 inches in fall. Iris hybrids German iris All colors 1/2-3 1/2 12-15; May-June Sun 3-10 After blooming; Susceptible to iris (Bearded iris) upright 2-4 borer and soft rot. Cut back to 6 inches in fall. Some cultivars rebloom in fall. Iris sibirica Blue, pink, 1 1/2-4 18-24; May-June Sun to 3-9 Spring when Cut back to 6 inches (Siberian iris) white, upright part shade necessary in fall. Tolerates yellow, moist soil. purple Lamiastrum galeobdolon Yellow archangel Yellow 1/2-1 1/2 12-18; May- Any 3-9 Spring; 2 Ground cover. (Golden dead nettle) spreading early June Variegated foliage. Can become invasive. Lamium maculatum Pink, white 1/2-1 12-18; May- Part shade 3-8 Spring; 2 Ground cover. (Spotted dead nettle) spreading early June Variegated forms are available. Can become invasive.

23 PERENNIAL SELECTION AND CARE GUIDE

Mature Division Other Flowering spread and (time of year; Special notes Botanical name common height form Bloom Hardiness frequency in (cultural uses, (Common name) name(s) Color (feet) (inches) period Light (zone) years) major pests, etc.) Lavandula angustifolia English lavender Purple, white 1-3 18; June- Sun to 5-9 No Trim back in spring. (Lavender) True lavender mound September part shade Tips are often killed over winter. Fragrant. Leontopodium alpinum White, 1/2-1 6-12; July-August Sun 4-9 Silver foliage. Mulch (Edelweiss) yellow basal to overwinter. Not foliage especially showy. Short-lived. Easy from seed. Requires excellent drainage. Leucanthemum X superbum White 1-4 12-24; June- Sun to 4-9 Spring; 2 Short-lived. Do not (Shasta daisy) mound September part shade crowd. Self-seeds, but not true to variety. Dead-head to prolong flowering. Syn. Chrysanthemum X superbum; C. maximum. Liatris spicata Prairie gay feather Purple, white 2-5 12-24; July-early Sun to 3-9 North American (Blazing-star) vertical September part shade native. Excellent cut flower. Ligularia spp. Groundsel Yellow 3-5 36-48; July-August Part shade 3-7 Spring; 3 Prefers moist, rich (Ligularia) Senecio upright soil and cool temperatures. Linum perenne Common blue flax Blue 1-1 1/2 12; May-August Sun 4-9 No Mulch to overwinter. (Perennial flax) mound Self-seeds. Requires good drainage. Limonium latifolium Perennial statice Purple 2 18-24; July-August Sun 3-9 No Salt tolerant. Short- (Sea lavender) basal lived. Requires foliage excellent drainage. Excellent dried flower. Liriope spicata Purple, white 1-1 1/2 12; July-August Sun to 5-8 Evergreen ground (Creeping lilyturf) clump part shade cover with black berries. Slugs can be a problem. Mulch in winter. Lobelia cardinalis Indian pink Red 2-4 12-18; July- Part shade 2-9 Grows best in moist, (Cardinal flower) vertical September acid soil and is short-lived. A summer mulch is desirable. Will tolerate full sun in moist soil. North American native. Lupinus hybrids All colors 3-4 18-24; May-June Sun to 3-6 No Grows best in acid (Lupine) upright part shade soils that are well drained and moist. Sensitive to hot summers. Short-lived but reseeds. Powdery mildew and rust are serious problems. Derived from North American species. Lychnis chalcedonica Red 1 1/2-3 12; June-early Sun 3-9 Tolerates wet soil. (Maltese-cross) mound September Lysimachia punctata Yellow loosestrife Yellow 2-3 18; June- Any 4-8 Spring; 3 Prefers a moist, (Garden loosestrife) mound September organic soil. Good for naturalizing. Can become invasive. Mertensia virginica Blue 1/2-2 12; April-May Part shade 3-9 No Foliage dies down in (Virginia bluebells) mound to shade July. North American native. Miscanthus sinensis Maiden grass Brown, white 3-7 24-48; Late Sun 4-10 Spring; 3 An ornamental grass. (Eulalia grass) vertical September- to part shade Some variegated November forms. Plumes remain throughout winter. Monarda didyma Wild bergamot Pink, red, 2 1/2-3 12-24; June- Sun 4-9 Spring; 2 Grows best in moist (Bee balm) Oswego tea white, mound August soils. It has lavender fragrant foliage and may become invasive. Powdery mildew and rust are common problems. North American native. Myosotis spp. Blue 1/2 12; May-August Part shade 3-8 Unneeded Prefers moist soil. (Forget-me-not) trailing Short-lived. Allow to self-sow for continued presence in garden.

24 PERENNIAL SELECTION AND CARE GUIDE Mature Division Other Flowering spread and (time of year; Special notes Botanical name common height form Bloom Hardiness frequency in (cultural uses, (Common name) name(s) Color (feet) (inches) period Light (zone) years) major pests, etc.) Nepeta X faassenii, N. mussinii Blue 1-1 1/2 24; May- Sun 3-8 Spring; 2 Fragrant foliage. (Catmint) mound September Attracts bees. Oenothera tetragona Yellow 1-3 12; June- Sun 3-8 Short-lived but (Sundrop) mound August showy. North American native. Oenothera missouriensis Ozark sundrops Yellow 3/4-1 1/2 12; June- Sun 3-8 Spring; 4 Stems emerge slowly (Evening primrose) spreading September in late spring. Good drainage in winter is important. North American native. Opuntia humifusa Yellow 1/2-1 24; June-July Sun 4-10 A hardy cactus; (Prickly pear) spreading tolerates poor soil. North American native, very prickly. Pods and fruits are edible. Paeonia hybrids Chinese peony Pink, red, 2-3 24-36; May-June Sun 2-10 May require staking. (Peony) Herbaceous peony white mound Grows best in deep, fertile soil. Papaver orientale Orange, 1 1/2-3 18-24; June Sun 2-7 No; after foliage Foliage dies down (Oriental poppy) pink, red, mound dies down only after flowering. white if necessary. Resents disturbance. Pennisetum alopecuroides Reddish 3-6 36; August- Sun 5-10 Mulch in colder (Fountain grass) brown mound early areas. Slow to October emerge. Good cut flower. Penstemon spp. Orange, 1/2-3 12-18; June- Sun to 3-7 Spring; 2 Short-lived. Mulch to (Beard-tongue) pink, purple, mound August part shade overwinter. Requires red, white well drained soil. North American native. Phlox maculata Spotted phlox Pink, white 2-3 24; June- Sun 3-9 North American (Phlox) mound August native. Mildew resistant. Phlox paniculata hybrids Summer phlox Blue, pink, 2-4 18; July- Sun to 3-8 May need staking. (Garden phlox) purple, red, vertical September part shade Grows best in white moist, well drained soil high in organic matter. A heavy feeder with fragrant flowers. Powdery mildew and rust are common problems. Derived from North American native. Phlox subulata Moss phlox Blue, pink, 1/2 18-24; April-June Sun to 2-9 Trim back after (Creeping phlox) red, white mat part shade flowering. Evergreen ground cover in warmer zones. Physalis alkekengi Japanese-lantern Orange seed 1 1/2 24; July-August Sun 3-9 Spring; 1 Self-seeds. May (Chinese-lantern plant) pods spreading become invasive. Physostegia virginiana Obedience Pink, white 2-4 24; July- Sun to 2-9 Spring; 2 May become (Obedient plant) False dragonhead mound October part shade invasive. North American native. Platycodon grandiflorus Blue, pink, 1 1/2-4 12-24; July- Sun to 3-8 No Long-lived. May (Balloon flower) white upright September part shade require staking. Emerges late in spring. Prefers acid soil. Polemonium caeruleum Greek valerian Blue 1 1/2-2 9-18; May-August Any 2-7 Prefers moist soil. (Jacob’s-ladder) mound Remove dead flowers to promote flowering. Polygonatum spp. King Solomon’s- White 1-4 12-36; May-June Shade 3-9 Long-lived. (Solomon’s-seal) seal arching Variegated types are stems available. Some species are native to North America. Polygonum affine Fleece flower Pink, red 1/2-1 12; May- Sun to 3-7 Spring; 2 Ground cover. Can (Smartweed) spreading October part shade be invasive. Potentilla spp. Five-fingers Pink, red, 1/2-2 12-24; May-August Sun- 3-8 Many are evergreen (Cinquefoil) yellow, white trailing part shade ground covers in zones 5 or warmer. Some are North American natives. Primula spp. All colors 1/2-1 6-12; April-June Varies 2-8 Spring; 2 Delicate flowers. (Primrose) basal Usually prefers a foliage moist soil high in organic matter. Good rock garden plants.

25 PERENNIAL SELECTION AND CARE GUIDE

Mature Division Other Flowering spread and (time of year; Special notes Botanical name common height form Bloom Hardiness frequency in (cultural uses, (Common name) name(s) Color (feet) (inches) period Light (zone) years) major pests, etc.) Prunella X webbiana Pink, red, 1/2-1 12; June-July Sun to 3-8 Ground cover. (Self-heal) white spreading part shade Related to Prunella vulgaris, a lawn weed. Pulmonaria saccharata Bethlehem sage Blue, pink 1-1 1/2 12-24; April-June Part shade 3-8 Variegated leaves. (Lungwort) spreading to shade May go dormant in summer. Pyrethrum roseum Painted daisy Pink, red, 1-3 12; June-July Sun to 3-7 Spring or fall; 2 Short-lived. Needs (Pyrethrum) white mound part shade support. Cut back to a few inches after flowering. A winter mulch should be used to reduce heaving. Syn. Chrysanthemum coccineum. Rodgersia spp. Pink, red, 3-6 48-64; June- Part shade 4-7 Coarse, attractive (Rodgersia) white mound August to shade foliage. Prefers moist soil. Very large accent plant. Rudbeckia fulgida ‘Goldsturm’ Orange coneflower Yellow with 2-3 24; July- Sun 3-9 Spring; 3 Self-seeds, but (Black-eyed Susan) black centers mound September seedlings aren’t true to type. One of the best perennials available. North American native. Salvia spp. Sage Blue, purple, 1-3 12-24; June- Sun 3-9 Easy to grow. (Perennial salvia) white mound September Tolerates dry soil. Saponaria ocymoides Pink, white 1/2-1 1; June- Sun 2-7 Cut back after (Soapwort) spreading September flowering. Requires good drainage. Scabiosa caucasica Scabious Blue, purple, 1-1 1/2 12; June- Sun 3-7 3-4 Resents wet soil. (Pincushion flower) white mound September Slow growing. Sedum X ‘Autumn Joy’ Pink to red 1-2 12-18; August- Sun to 3-10 A succulent. Flowers (`Autumn Joy’ sedum) mound October part shade attract bees. Long- lived. Sedum spp. Pink, red, 1/4-1 1/2 6-18; June- Sun 3-8 Succulent ground (Stonecrop) white, yellow spreading September cover. Red foliage types are available. Sempervivum spp. Houseleek Purple, white 1/2 9; mat July-August Sun 3-8 A succulent. Leaves (Hen-and-chickens) Liveforever are in a basal rosette. Grown primarily for its foliage. Sidalcea malvaeflora Checker-mallow Pink, white 3 12-24; June- Sun 4-7 Spring; 3-4 Short-lived. Dislikes (Checkerbloom) mound August heat. Stokesia laevis Cornflower aster Blue, white 1-1 1/2 12-18; July- Sun to 5-9 Mulch to overwinter. (Stokes’ aster) mound September part shade Resents wet soil. Thalictrum spp. Lavender, 3-5 24-36; June- Sun to 3-7 Long-lived. Used (Meadow rue) yellow, white mound August part shade best as background plants. Prefers moist soil. Thymus spp. Pink, white, 1/4-1 12; June- Sun 4-10 Ground cover. (Thyme) blue spreading August Fragrant, sometimes variegated foliage. Edible herb. Tradescantia X andersoniana Blue, pink, 1 1/2-3 15-30; June- Any 4-9 Spring; 2 May become (Spiderwort) purple, white mound August invasive. Cut back to ground in fall. North American native. Trollius hybrids Yellow, 2 24-36; June Sun to 4-6 Avoid Grows best in rich, (Globeflower) orange mound part shade moist soils. Cut back foliage in late summer. Veronica spp. Blue, pink, 1/2-4 12-18; June- Sun to 3-8 Spring; 4 Tolerates wet soils. (Speedwell) purple, white mound or August part shade Intense blue flowers. spreading Viola spp. Sweet violet Blue, purple, 1/2-1 12; April-June Part shade 4-9 Spring; 3 Grows best in moist (Violet) Garden violet red, white, mound to shade soils high in organic yellow matter. Flowers are fragrant. Some species are North American natives. Yucca filamentosa White 3-5 24; July-August Sun 4-10 Propagated by (Adam’s-needle) vertical offsets from crown. Drought tolerant. Needs good drainage.

26 BLOOM CHART

E = Early M = Middle * Times are approximate for the middle of USDA Zone 5. L = Late

February March April May June July August September October Perennial E M L E M L E M L E M L E M L E M L E M L E M L E M L Ajuga spp. X X X X X X Arabis albida X X X X X X X Aubrieta deltoidea X X X X X X X X X Bergenia cordifolia X X X X X X Brunnera macrophylla X X X X X X X X X Ceratostigma plumbaginoides X X X X X X Chrysogonum virginianum X X X X X X X X X X X X X X X X X X Doronicum caucasicum X X X X X X Euphorbia epithymoides X X X X X X Festuca cinerea X X X X X X X X X X X X X X X X X X X X X Geranium spp. X X X X X X X X X X X X X X X Helleborus niger, H. orientalis X X X X X X X X X Iberis sempervirens X X X X X X Incarvillea delavayi X X X X X X X X X Mertensia virginica X X X X X X Phlox subulata X X X X X X Primula spp. X X X X X X Viola spp. X X X X X X Aegopodium podagraria X X X X X X Aquilegia spp. X X X X X X X X X Armeria maritima X X X X X X Aurinia saxatilis X X X Baptisia australis X X Centranthus ruber X X X X X X X X X X X X Cerastium tomentosum X X X X X X Convallaria majalis X X X X X X Dianthus X allwoodii X X X X X X X X X X X X X X Dicentra eximia X X X X X X X X X X X X X X X Dicentra spectabilis X X X X X X Dictamnus albus X X X X X X Epimedium spp. X X X Galium odoratum X X X X X X Geum quellyon X X X X X X X X X X X X X X X X X X Heuchera sanguinea X X X X X X X X X X X X Iris hybrids X X X X X X X X X X Iris sibirica X X X X X X Lamiastrum galeobdolon X X X Lamium maculatum X X X Lupinus hybrids X X X X X X Myosotis spp. X X X X X X X X X Nepeta X faassenii, N. mussinii X X X X X X X X X X X X X X X X X X Paeonia hybrids X X X X X X X X X Polemonium caeruleum X X X X X X Polygonatum spp. X X X X X X Polygonum affine X X X X X X X X X X X X X X X X X Potentilla spp. X X X X X X X X X Trollius hybrids X X X X X X Achillea millefolium and hybrids X X X X X X X X X X Achillea X ‘Coronation Gold’ X X X X X X X X X X X X X X Anthemis tinctoria X X X X X X X X X X X X X X X Artemisia schmidtiana X X X X X X X X X X X X Aruncus dioicus X X X X X X X X X Asclepias tuberosa X X X X X X X X X Astilbe X arendsii X X X X X X X X X Calamagrostis acutiflora X X X X X X X X X X X X Campanula glomerata X X X X X X X X X X X X Centaurea montana X X X X X X X X X X X X Coreopsis grandiflora, C. lanceolata X X X X X X X X X X X X X X X Delphinium X elatum X X X X X X X X X X X X X X X Erigeron speciosus X X X X X X X X X X X X X X X

27 BLOOM CHART

February March April May June July August September October Perennial E M L E M L E M L E M L E M L E M L E M L E M L E M L Festuca cinerea XX X X Gaillardia X grandiflora X X X X X X X X X X X X X X X Gypsophila paniculata X X X X X X X X X X X X Hemerocallis spp. and cultivars X X X X X X X X X Iris kaempferi XX X X Lavandula angustifolia X X X X X X X X X X X X Leucanthemum X superbum X X X X X X X X X X X X Linum perenne X X X X X X X X X Lychnis chalcedonica X X X X X X X X X X Monarda didyma XX X X Oenothera missouriensis X X X X X X X X X X X X Opuntia humifusa X X X Papaver orientale X X X X X X Penstemon spp. X X X X X X X X X Prunella X webbiana X X X X X X Pyrethrum roseum X X X Salvia spp. X X X X X X X X X X X X X X X Saponaria ocymoides X X X X X X X X X X X X Scabiosa caucasica X X X X X X X X X X X X Sidalcea malvaeflora X X X X X X Thymus spp. X X X X X X Tradescantia X andersoniana X X X X X X X X X Veronica spp. X X X X X X X X X Belamcanda chinensis X X X X X X X X X Ceratostigma plumbaginoides X X X X X X X X X Echinacea purpurea X X X X X X X X X Echinops ritro X X X X X X X X X X X X Heliopsis helianthoides X X X X X X X X X X X X Hibiscus moscheutos X X X X X X Leontopodium alpinum X X X X X X Liatris spicata X X X X X X X Limonium latifolium X X X X X X Ligularia spp. X X X X X X Liriope spicata X X X X X X Lobelia cardinalis X X X X X X X X X X X X Lysimachia punctata X X X X X X Phlox paniculata X X X X X X X X X Physalis alkekengi X X X X X X Physostegia virginiana X X X X X X X X X Platycodon grandiflorus X X X X X X X X X X X X Rodgersia spp. X X X X X X Rudbeckia fulgida ‘Goldsturm’ X X X X X X X X X Sempervivum spp. X X X X X X Stokesia laevis X X X X X X X X X Thalictrum spp. X X X X X X Yucca filamentosa X X X X X X Aconitum spp. X X X X X X X X X Anemone X hybrida, A. vitifolia, A. hupehensis X X X X X X X X X Dendranthema grandiflora X X X X X X X X X Helenium autumnale X X X X X X Helianthus X multiflorus X X X X X X Hosta spp. X X X X X Pennisetum alopecuroides X X X X X X X Sedum X ‘Autumn Joy’ X X X X X X X X X Aster novae-angliae XX X X Eupatorium coelestinum X X X X X X Miscanthus sinensis XX X X

28 CROSS-REFERENCE INDEX

Aconite/Aconitum Creeping phlox/Phlox subulata Heliopsis/Heliopsis helianthoides Adam’s-needle/Yucca filamentosa Cushion spurge/Euphorbia epithymoides Hellebore/Helleborus Alpine aster/Aster alpinus Daisy fleabane/Erigeron speciosus Hen-and-chickens/Sempervivum Astilbe/Astilbe Daylily/Hemerocallis Herbaceous peony/Paeonia hybrids ‘Autumn Joy’ Sedum/Sedum X ‘Autumn Delphinium/Delphinium Hosta/Hosta Joy’ Edelweiss/Leontopodium alpinum Houseleek/Sempervivum Avens/Geum quellyon English lavender/Lavandula angustifolia Indian pink/Lobelia cardinalis Baby’s-breath/Gypsophila paniculata Eulalia grass/Miscanthus sinensis Jacob’s-ladder/Polemonium caeruleum Balloon flower/Platycodon grandiflorus Evening primrose/Oenothera missouriensis Japanese anemone/Anemone Barrenwort/Epimedium Evergreen candytuft/Iberis sempervirens Japanese iris/Iris kaempferi Basket-of-gold/Aurinia saxatilis False dragonhead/Physostegia virginiana Japanese-lantern/Physalis alkekengi Beard-tongue/Penstemon False indigo/Baptisia australis Joe-pye weed/Eupatorium maculatum, Bearded iris/Iris hybrids False spirea/Astilbe X arendsii E. purpureum Bee balm/Monarda didyma Feather reed grass/Calamagrostis acutiflora Jupiter’s-beard/Centranthus ruber Bellflower/Campanula Fern-leaf yarrow/Achillea X ‘Coronation King Solomon’s-seal/Polygonatum Bergenia/Bergenia cordifolia Gold’ Lance-leaf coreopsis/Coreopsis Bethlehem sage/Pulmonaria saccharata Five-fingers/Potentilla Lavender/Lavandula angustifolia Bishop’s weed/Aegopodium podagraria Fleabane/Erigeron speciosus Leadwort/Ceratostigma plumbaginoides Black-eyed Susan/Rudbeckia fulgida Fleece flower/Polygonum affine Lenten rose/Helleborus Blackberry lily/Belamcanda chinensis Forget-me-not/Myosotis Leopard’s-bane/Doronicum caucasicum Blanket flower/Gaillardia X grandiflora Fountain grass/Pennisetum alopecuroides Lily-of-the-valley/Convallaria majalis Blazing-star/Liatris spicata Fringed bleeding-heart/Dicentra eximia Liveforever/Sempervivum Bleeding-heart/Dicentra spectabilis Funkia/Hosta Lungwort/Pulmonaria saccharata Blue fescue/Festuca cinerea Garden loosestrife/Lysimachia punctata Lupine/Lupinus hybrids Bluebells/Campanula Garden peony/Paeonia hybrids Maiden grass/Miscanthus sinensis Bugleweed/Ajuga Garden phlox/Phlox paniculata hybrids Maiden pink/Dianthus deltoides Butter daisy/Coreopsis Garden violet/Viola Maltese-cross/Lychnis chalcedonica Butterfly weed/Asclepias tuberosa Gas plant/Dictamnus albus Meadow rue/Thalictrum Candytuft/Iberis sempervirens Gay-feather/Liatris Michaelmas daisy/Aster Cardinal flower/Lobelia cardinalis German statice/Goniolimon tartaricum Mist flower/Eupatorium coelestinum Carpathian harebell/Campanula carpatica Globe thistle/Echinops ritro Monkshood/Aconitum Carpet bugle/Ajuga Globeflower/Trollius hybrids Moss phlox/Phlox subulata Catmint/Nepeta X faassenii, N. mussinii Goat’s-beard/Aruncus dioicus Mountain bluet/Centaurea montana Checkerbloom/Sidalcea malvaeflora Golden century/Centaurea macrocephala Mum/Dendranthema grandiflora Checker mallow/Sidalcea malvaeflora Golden dead nettle/Lamiastrum galeobdolon New England aster/Aster Chinese-lantern plant/Physalis alkekengi Golden Marguerite/Anthemis tinctoria Obedience/Physostegia virginiana Chinese peony/Paeonia hybrids Goldenstar/Chrysogonum virginianum Obedient plant/Physostegia virginiana Christmas rose/Helleborus Goldentuft alyssum/Aurinia saxatilis Orange coneflower/Rudbeckia fulgida Cinquefoil/Potentilla Goutweed/Aegopodium podagraria ‘Goldsturm’ Clustered bellflower/Campanula glomerata Grass pink/Dianthus Oriental poppy/Papaver orientale Columbine/Aquilegia Greek valerian/Polemonium caeruleum Oswego tea/Monarda didyma Common blue flax/Linum perenne Green-and-gold/Chrysogonum virginianum Oxeye/Heliopsis helianthoides Common yarrow/Achillea millefolium Groundsel/Ligularia Ozark sundrops/Oenothera missouriensis Coralbells/Heuchera sanguinea Hardy ageratum/Eupatorium coelestinum Painted daisy/Pyrethrum roseum Cornflower aster/Stokesia laevis Hardy aster/Aster Peony/Paeonia hybrids ‘Coronation Gold’ yarrow/Achillea X Hardy carnation/Dianthus Perennial flax/Linum perenne ‘Coronation Gold’ Hardy chrysanthemum/Dendranthema Perennial larkspur/Delphinium Cottage pink/Dianthus grandiflora Perennial salvia/Salvia Cranesbill/Geranium Hardy geranium/Geranium Perennial statice/Limonium latifolium Creeping lilyturf/Liriope spicata Hardy gloxinia/Incarvillea delavayi Perennial sunflower/Helianthus X multi- Harebell/Campanula florus, Heliopsis helianthoides

29 CROSS-REFERENCE INDEX

Phlox/Phlox maculata ‘Silver Mound’ artemisia/Artemisia Wall cress/Arabis albida Pincushion flower/Scabiosa caucasica schmidtiana Wild bergamot/Monarda didyma Pink/Dianthus Silver queen/Artemisia ludoviciana Wild bleeding-heart/Dicentra eximia Plantain lily/Hosta Smartweed/Polygonum affine Wild indigo/Baptisia australis Prairie gay-feather/Liatris spicata Sneezeweed/Helenium autumnale Windflower/Anemone X hybrida Prickly pear/Opuntia humifusa Snow-in-summer/Cerastium tomentosum Wolfsbane/Aconitum Primrose/Primula Soapwort/Saponaria ocymoides Wormwood/Artemisia schmidtiana Purple coneflower/Echinacea purpurea Solomon’s-seal/Polygonatum Yarrow/Achillea millefolium Purple rock cress/Aubrieta deltoidea Speedwell/Veronica Yellow archangel/Lamiastrum galeob- Pyrethrum/Pyrethrum roseum Spiderwort/Tradescantia X andersoniana dolon Red valerian/Centranthus ruber Spotted dead nettle/Lamium maculatum Yellow chamomile/Anthemis tinctoria Rock cress/Arabis albida Spotted phlox/Phlox maculata Yellow loosestrife/Lysimachia punctata Rodgersia/Rodgersia Stokes’ aster/Stokesia laevis Rose mallow/Hibiscus moscheutos Stonecrop/Sedum Sage/Salvia Summer phlox/Phlox paniculata hybrids Scabious/Scabiosa caucasica Sundrops/Oenothera Sea lavender/Limonium latifolium Sweet violet/Viola Sea pink/Armeria maritima Sweet woodruff/Galium odoratum Sea thrift/Armeria maritima Thread-leaf coreopsis/Coreopsis verticillata Self-heal/Prunella X webbiana Thrift/Armeria maritima Senecio/Ligularia Thyme/Thymus Shasta daisy/Leucanthemum X superbum Tickseed/Coreopsis spp. Siberian forget-me-not/Brunnera macrophylla True lavender/Lavandula angustifolia Siberian iris/Iris sibirica Turtlehead/Chelone Silver king/Artemisia ludoviciana Violet/Viola Virginia bluebells/Mertensia virginica

30 Grid Sheet for Planning Your Garden

31 North Central Regional Extension publications are subject to peer review and prepared as a part of the Cooperative Extension activities of the 13 land-grant universities of the 12 North Central states, in cooperation with the Extension Service-U.S. Department of Agriculture, Washington, D.C. The following states cooperated in making this publication available. University of Illinois *Michigan State University North Dakota State Univ. University of Wisconsin Ag. Publication Office Room 10B Ag Hall Extension Communications Cooperative Extension Publications 69 Mumford Hall East Lansing, MI 48824-1039 Box 5655, Morrill Hall Rm. 245 Urbana, IL 61801 (517) 355-0240 Fargo, ND 58105 30 N. Murray St (217) 333-2007 (701) 237-7881 Madison, WI 53715-2609 (608) 262-3346 Purdue University University of Minnesota Ohio State University Publication Mailing Room Distribution Center Publications Office 301 S. Second Street 3 Coffey Hall, 1420 Eckles Ave. 385 Kottman Hall Lafayette, IN 47901-1232 St. Paul, MN 55108-6064 2021 Coffey Rd. (317) 494-6795 (612) 625-8173 Columbus, OH 43210-1044 (614) 292-1607 Kansas State University University of Missouri South Dakota State Univ. Distribution Center Extension Publications Ag Comm. Center Umberger Hall 2800 McGuire Box 2231 Manhattan, KS 66506-3400 Columbia, MO 65211-0001 Brookings, SD 57007-0892 (913) 532-5830 (314) 882-2792 (605) 688-5628

*Publishing state For copies of this and other North Central Regional Extension publications, write to: Publications Office, Cooperative Extension Service, in care of the university listed above for your state. If they do not have copies or your state is not listed above, contact the publishing state as specified. Programs and activities of the Cooperative Extension Service are available to all potential clientele without regard to race, color, sex, national origin, religion, age or disability. In cooperation with NCR Educational Materials Project Issued in furtherance of Cooperative Extension work, Acts of Congress of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture and Cooperative Extension Services of Illinois, Indiana, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota and Wisconsin. Gail Imig, director, MSU Extension, East Lansing, Michigan 48824.

Major Rev. 11:94-35M-LJ-IN, Price 50¢, Single copy free to Michigan residents. File: Gardening – Flowers.

32 Growing CORRECTIONSHEET Perennials

The flowers listed in the This bed is designed to provide continuous bloom through- illustration at the top of out the growing season. page 9 in NCR 556, “Growing Perennials” are ANNUALS. Following is the correct version for PERENNIALS. We are sorry for any difficulties this has caused.

North Central Regional Extension Publication No. 556

(Correction Sheet, Feb. 1995)