Bulletin of the American Rock Garden Society
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Bulletin of the American Rock Garden Society Volume 48 Number 2 Spring 1990 Cover: Physaria alpina Painting by Carolyn Crawford, of Arvada, Colorado. A photograph by Panayoti Kelaidis served as her model. Bulletin of the American Rock Garden Society Features Drabas for an Alpine Spring, by Jeanie Vesall 83 Germination in Crucifers, by Norman C. Deno 89 Pot that Draba!, by Lee Morris Raden 95 Discovering Drabas with the Hand Lens, by Dick Bartlett 101 Color Forms of Rocky Mountain Erysimums, by Robert Price 109 Physarias: April's Garden Gold, by Panayoti Kelaidis 111 The California Garden, by Hariand Hand 125 How I Began to Garden and Began Again, by Marjory Harris 131 Departments Troughs: Alpines in the Fog Belt, by Wallace Wood 138 Journal Articles 140 Plant Portrait: Aethionema oppositifolium, by Anita Kistler 145 Books 146 Obituaries 147 Errata 149 Draba polytricha 82 Bulletin of the American Rock Garden Society Vol. 48(2) Drabas for an Alpine Spring by Jeanie Vesall Native Minnesotans revel in the the tightly fitted limestone crevice beds length and severity of our winters. As crowded with miniature cushions. gardeners, we stoically suffer, con• Plants such as lewisias, saxifrages, and tenting ourselves with seed lists and drabas were new to us. These were study weekends. An unseasoned Feb• the plants we wanted to grow. ruary thaw finds many of us roaming But pleasing alpines among the the edges of our snowy gardens boulders of our garden proved to be a attempting to alleviate a raging case challenge. The scale was wrong and of "cabin fever." For Minnesota the soil too fat. In our early enthusi• gardeners spring's arrival will always asm, we carefully collected plant be a miracle. souvenirs from the mountains, only to My husband David and I first have them immediately succumb. shared our interest in alpine wild flow• One particular plant did survive, a ers on our honeymoon, backpacking small, white-flowered draba from the in Glacier National Park. Exquisite Bighorn Mountains. Surely this genus flowers were everywhere on the heels must be particularly adaptable. Was of the retreating snow. No Minnesota this more than beginners' luck? We spring was ever like this. Years later decided to try more species of this we learned that there were special group. gardeners who had tamed some of Now, in late March or early April these plants. We made our decision: the tiny, crowded buds on the draba we would be rock gardeners. cushions bring the first hint of spring. We planted our first rock garden As the bright yellow and white blos• with the colorful, predictable phloxes soms open, bees from our hive visit and dianthus. Yet touring the gardens often. And, if the weather is just of local experts we found that large right, Saxifraga oppositifolia is in mats of color were not the center• full flower at the same time, creating pieces. Instead, we were fascinated by perfect color harmony on a miniature 83 scale. These first flowers in our rock raised bed constructed of close-fitting garden rate a boastful call from David Mississippi River limestone is equally to a rival gardener. successful. This bed is built up over a In the wild, drabas are an evolu• mound of limestone gravels of several tionary successful genus of over 250 sizes, coarse sand, peat moss, and species mostly found in the moun• assorted rocks. As the tiny plants are tains and boreal regions of the North• positioned in the crevices, we remove ern Hemisphere. Particularly well some of the basic soil mixture and represented in western North Ameri• refill around the plant with an unmea• ca, Europe, and Turkey, drabas favor sured concoction of mostly limestone rocky and gravelly areas without and granitic grit, and much smaller much competition from other plants. proportions of our sugar-fine acid While some gardeners, including sand, oak leaf mold, and a dash of Ingwersen, may dismiss many drabas bonemeal. The bonemeal, which we as of "only botanical interest," we used most consistently last year, enjoy the subtle differences in foliage seemed to improve flowering provid• and flower. Unlike so many rock ed it was at the very bottom of the plants, the genus has a purity unadul• planting hole, out of reach of our terated by the meddling of horticul- resident raccoons. The raised bed turalists. Even natural hybrids are faces south but receives some midday uncommon. I like an alpine plant that shade. still retains its wild form. We water the raised bed thorough• After several years of growing ly once a week and more often if the drabas, we would rate them among weather is hot and windy. During the the most dependable of all alpine hottest part of the summer, we mist cushion plants. These small, brilliantly the garden in the morning in addition flowered buns are easy to grow and to regular watering. Sharp drainage are able to survive a wide variety of assures the plants a longer, healthier conditions, making them a good life, and the cushions assume a char• choice for a beginning rock gardener. acteristic mounding form. In our Unlike some high alpine plants, many large, boulder-strewn scree bed, drabas display the same beautiful planting in pockets of soil with a form and flower in the garden as they good dose of grit in the individually do in their natural habitat. The best prepared holes also encourages con• place to showcase these tiny plants is densed growth. a trough, raised bed, or rocky crevice. Most of the drabas remain Most draba species develop a deep disease- free with any of these grow• taproot and appreciate the protected ing conditions. Weekly fungicide root run of a crevice. The cushions spraying during the heat and humidity are supported by the surrounding of our summers keeps the tightest, rock and thick gravel mulch and fuzziest plants healthy. As in the wild, quickly assume their tight alpine drabas like their own space in the habit. garden. We have had some losses For the same reasons, some when the foliage of other plants drabas do well in our tufa bed. Our touches the cushions. And ants 84 Bulletin of the American Rock Garden Society Vol. 48(2) tunneling below the cushions need to is the method of choice for bringing be dealt with quickly. plants home from the wild. Our first selections of drabas were Catalog and seedlist writers, limited to the offerings from various having exhausted all the possible mail-order nurseries, but we quickly descriptions of yellow, fuzzy cushions, built a collection of plants from the leave the beginner with a blurred numerous species listed in seed ex• picture of which drabas to choose. changes. The whole genus is highly Botanical taxonomy doesn't make variable in the wild, and species over• this choice any easier. The tiny size of lap and intergrade. Therefore, the plants and the numerous similari• gardeners should try the same species ties between the species can lead to from several different sources and questionable identification or none at select the seedlings with the best all. Thus, one of our favorites from characteristics. the Wallowas, a choice cushion of Drabas are not difficult from seed. wooly, gray rosettes, is still known to Germination, even of older seed, is us simply as Draba sp. It was a nice rapid, with no cold treatment needed. gift from the Vanderpoels of Barring- David starts the seeds in our base• ton, Illinois. By trying many species ment under lights. As with all our we have, however, discovered that alpine seedlings, he transplants them there are drabas for every gardener. when very tiny (first true leaves) to a Some are easy and good-looking, gritty mix. Because I have an abun• others impossibly difficult to grow and dance of seedlings, I can plant drabas extremely choice. throughout the crevice bed, giving it While some might say it is not the the look of an alpine bunnery. best of the North American drabas, Garden-grown drabas occasionally set D. \ncerta is easy and one of our lots of seed. Collecting it is good favorites. Our plants came from seed insurance against the loss of some of gathered during a memorable trek to the shorter-lived species. Self-sown Mt. Townsend on the Olympic Penin• seedlings occur, too. Even sowing sula with the Lowrys, Phil Pearson, seed directly into a crevice or piece of and Steve Doonan. The gray-green tufa will often produce plants. cushions are looser and more open Cuttings are also an effective than some, but the large, light yellow method of propagation. The trickiest flowers are produced in abundance. part is removing a bit of the cushion Draba paysonil var. treleasii, from with a razor while leaving fingers the same trip, is now, after two sum• intact. I have rooted cuttings taken in mers in the crevice bed, a minute late summer in clay pots filled with fuzzball of twelve rosettes. Tom coarse sand and protected with a Vanderpoel, another aficionado of plastic cup in the coldframe. In mid• the genus, rates D. paysonii (see summer last year, I succeeded by photo, p. 100) as the finest North placing the whole pot of cuttings in a American draba. He saw it in perfec• sealed zip-locking bag under the base• tion on Clay Butte in the Beartooth ment lights, a much cooler place than Mountains of Wyoming. Flowering out-of-doors. Either seeds or cuttings along with Saxifraga oppositifolia Drabas for an Alpine Spring 85 on a steep scree, the ancient 4" cush• Another common draba of the ions were covered with huge, American West, D.