Hypothesis Was Formulated That the Cause of Black Shoots Lies in The
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no. 8 / November 2005 This Flower Bulb Research Program Newsletter is published by the hypothesis was formulated that the cause of black of freezing damage is high. This method is devel- Royal Dutch Wholesalers Association for Flowerbulbs and Nurserystock shoots lies in the temperature in the soil and during oped by PPO. in cooperation with Dr. Bill Miller of Cornell University. storage before freezing. A correlation was observed Information: [email protected] between the losses by black shoots and a temporary increase in soil temperature after a period of low temperatures, especially in lilies grown in France. Producing and Using Bulbous Plants for Mixed Its job is to be round and robust so it can basically The problem also occurs in lilies grown in Holland. Planters fill in between plants and cover the media in the In that case the temperatures during transport and container. The second plant is the “spiller”. Its job is storage are probably the cause. The physiological By Dr. Terri Starman, Texas A&M University to drape over the side of the container and softens explanation of the problem is that the relatively low 100% damage the container’s hard edge and add an element of line soil temperatures in fall gradually break the dor- by black shoots in Everyone knows that container gardens are the latest and length to the mixed planting. The third plant is Oriental lilies in mancy of the shoot. Any rise in temperature, even the greenhouse in gardening craze. They have been popular for several the “thriller”. Its job is to attract the consumer’s eye temperatures like 5 to 8 °C, induces the development August by storing years now but they are forever evolving. The first and delight them so that they will be happy and buy of the new shoot. the bulbs at 10 to container gardens were produced in color bowls more container gardens in the future. A fourth plant 12 °C for 3 weeks with colorful seed propagated annuals planted may be needed as another “filler” to help fill in Once this development has started it cannot be before freezing. around a Dracaena ‘Spikes’ plant. Kathy Pufahl can and/or add some height depending on the container Photo: VWS stopped and freezing these bulbs will result in black be credited with opening our eyes to using more di- size. shoots. verse and unusual types of plants, particularly herba- ceous perennials, mixed with the annuals. She was a A bulbous plant can make a great “thriller” plant in a In an experiment carried out by the export company whiz at cramming these new and different plants container garden when it has a large colorful flower VWS it was found that Oriental lilies that were fro- into gorgeous containers. At this time I see three like a lily, amaryllis or dahlia; when it pops out of zen immediately upon arrival half of January new trends in container gardening and the evolution the ground with a splash of color like a tulip or daf- showed no black shoots when the bulbs were forced of container gardens will no doubt continue. The fodil; when it has an unusual flower form like a calla in a greenhouse in August. When the bulbs were first new trend is the increased manufacturing inno- or Eucomis; or, when it has an unusual foliage form stored at 2 °C for 3 weeks before freezing a low per- No freezing dam- vations of upscale containers made of more weather or texture like Incarvillea or Begonia. Bulb plants centage of the bubs showed black shoots in August. age by black resistant materials like those made with resins. are also thrilling in container gardens because of shoots in lilies Decorative containers are selling like “hot cakes” as their beautiful and unusual flower colors. For exam- Storing the bulbs at 10 to 12 °C for 3 weeks before that were frozen freezing caused 100% black shoots. These results immediately people’s living spaces extend out from the homes ple, black flowers are very popular for making eye- confirm the idea that a temporary rise in temperature upon arrival (half and into their gardens. Decorative containers be- popping mixed plantings. during the cold storage before freezing is the cause of January). come part of the furnishings in garden rooms. of the problem. From this experiment it can be con- (Photo 1). An example of Eucomis 'Bicolor' show- cluded that in many cases Oriental bulbs should be The second trend I see is using all of the different ing-off as a “thriller” is in this container garden. An- frozen as soon as possible after harvest. When the horticultural classifications of plants mixed in the other interesting feature of this container garden is bulbs must be stored for some time before freezing same container. In addition to the seed annuals and that a microclimate was achieved within it. The or transported this must be d one at temperatures as herbaceous perennials come grasses, herbs, woody taller, sun-loving plants provided shade to the shade- close to zero as possible. Whether a batch of bulbs Address: Address: shrubs, vegetative annuals, tropicals, succulents, loving plants below them. Plants accompanying the Contact Bill Miller: and, yes, bulbs. That is what our experiment was Eucomis are Southern Maidenhair Fern, Huechera is sensitive to black shoots can be determined by Dept. of Horticulture measuring the breaking index of shoot juice during Cornell UniversityDept. of Horticulture Weeresteinstraat 120 about a year ago and what this article is about – to 'Amber Waves', Ajuga 'Black Scallop', Begonia the period between harvest and freezing. The break- 134 Plant ScienceCornell Building University P.O Box 170 take a look at using bulbs in mixed plantings. (See 'Fimbriola Orange', Hosta 'Fragrant Bouquet', Co- ing index is an indicator for the amount of sugar in Ithaca,134 NY Plant 14853 Science Building 2180 AD Hillegom Experiment below). leus 'Sedona', Tatting Fern, Japanese Painted Fern, USA the shoot, acting as anti-freezing agent. When the Ithaca, NY 14853 Phone: +31 252 53 50 80 Streptocarpella ‘Concord Blue’and Impatiens sugar level increases during this period (multiple USA Fax: +31 252 53 50 88 Now that containers have become as beautiful as the 'Infinity Salmon’. measurements), the lilies can be frozen safely. When Phone: + 1 0016072272780: [email protected] plants, a third new trend is to simplify the plantings. a decrease in sugar level is measured dormancy is Fax: + 1 0016072559998: One way to simplify a container garden is to use just broken, shoot development has started and the risk [email protected] three plant species. One plant is the “filler”. Research Nesletter | 2005 Research Newsletter | 2005 winter and spring as well. Nothing gives the feeling Dahlias, Zantedeschia, Eucomis, Hippeastrom, In- that spring is in the air better than spring-blooming carvillea, Begonia, and Lilium were potted with 1 bulbs, but there are also lots of bulbs that bloom in bulb per 6" (15 cm) standard pot. Crocosmia and fall and summer too. Gladiolus were potted 2-3 bulbs per 6" (15 cm) azalea pot. Imp. Orchid Nanus, Leucocoryne, and (Photo 3). Here is an example of a container garden Calachortus were potted 3 bulbs per 4.5" (11 cm) that emphasizes the spring season by using a mix- geranium pot. ture of spring plants including tulips, cosmos, dusty Miller and violas. Photo 1. (Photo 2). In this container garden, beautiful Calla Photo 10. 'Schwarzwalder' is complemented by Begonia 'Sinbad', Eranthemum 'Ebony', Dahlia 'Gallery Art Mar. and we continued making containers once per Fair', Coleus 'Merlot', Ajuga 'Black Scallop', week until 21 May. Mixed containers were made Helichrysum 'Silver Spike', Guara 'Pink Fountain', with fully-grown flowering bulbs and companion Photo 3. Pelargonium 'Pink Bicolor', and Impatiens ' Infinity plants. This was done initially because we didn't Pink'. 2. Unusual flowers and foliage. know what color the bulb flowers would be or their Contrast makes container gardens interesting. Con- growth habit. Later with knowledge of the color and plant form of the bulb species, we made some mixed trast is developed by varying the shape, size, tex- Photo 9. tures and color of flowers and foliage. There are so container gardens when the bulbs were emerging. In many various shapes of flowers in bulbous plants. All genera received clear water irrigation from pot- the mixed plantings, we used an average of nine ting until emergence. After emergence they re- plants per 14" (36 cm) container. (Photo 4). Just look at the diversity of foliage forms ceived 200 ppm (mg/liter) 15-16-17 until 24 Mar. Please visit our web-site at http://aggie- in this container garden using Calla 'Captain Ro- when the fertilizer was changed to 20-10-20. They horticulture.tamu.edu/floriculture/container- mance', Leucocoryne 'Andes', Incarvillea 'Del Pink', were grown at 65 °F day / 55 °F night (18 °C day / garden/index.html to learn more about producing Coleus 'Dipt in Wine', Heuchera 'Amber Waves', 13 °C night) from 12 Feb to 17 Mar. and 75 °F day / mixed plantings and see all of the container gardens Dahlia 'Gallery Cezanne', Salvia 'Tri Color', Lamium 65 °F night (24 °C day / 18 °C night) after that. The with bulbs that were made in this experiment. 'Pink Pewter', and Gaura 'Ballerina Blush'. first planting of bulbs received no chemical plant growth regulators. The Dahlias and Lilies in the sec- Problem of black shoots in Oriental Lilies closer ond planting received a 4 ppm (mg/liter) Arest to a solution drench, 1.5 weeks after potting. By Henk Gude and Hans Kok, Applied Plant Photo 2.