Collector and nurseryman Darrell Probst is uncovering new gems in this familiar genus
by TOM FISCHER photography by RICHARD W. BROWN
Just when you think you’ve finally gotten a grasp on the major perennial groups, something comes along to send seismic rumblings through your tidy little world. Three new species of turquoise-blue corydalis. A smoke tree with blazing yellow foliage. Or, to get to the matter at hand, a whole new group of diverse and fascinating epimediums, with flowers, foliage, and growth habits unlike any most of us have ever seen. If you thought that epimediums were nothing more than pleasant, rather unexciting groundcover plants, useful for filling up those out-of-the-way dry, shady spots, get ready. Darrell Probst has a few surprises for you.
A tall, solidly built man with a shock of blond hair and an easygoing manner, Probst seems at first an unlikely proselytizer for this unsung group of plants. Until, that is, we reach the growing area at his nursery, Garden Vision, which is tucked into a winding, woodsy road in the north-central Massachusetts town of Hubbardston. As we walk past row upon row of raised beds, each covered with billowing mounds of foliage and partly shaded by limbed-up pines and oaks, Probst’s pace slows; his eyes start darting from plant to plant. Pausing by a plant with particularly shiny foliage, Probst stops dead in his tracks. “Look at the gloss on that,” he says, in the tones of the hopelessly smitten. “That green keeps getting darker but stays just as polished the whole season.”
Opposite: Probst not only collects new epimediums, he also hybridizes them and makes selections of more familiar varieties. The striking bicolor ‘Be My Valentine’, shown here, is a compact selection of E. ?youngianum. Above: Darrel Probst at his nursery, Garden Vision. Below: Probst with a seedling of the Chinese species E. wushanense.
Garden Vision is the mother lode of epimediums—all told, there are some 1,500 different varieties growing here. Even though I’m visiting in June—not a time of year I associate with blooming epimediums—many of the clumps are still covered with sprays of delicate flowers in yellow, white, pink, or lilac. Some are just late bloomers. But others are rebloomers, a phenomenon present only among certain newly discovered or imported Chinese species; on top of that, all but two of these newcomers have evergreen foliage. Probst has traveled to China three times since 1996 to collect epimediums. It’s probably safe to say that he now has the most extensive collection of Chinese species in the country. As word of these plants has penetrated gardening circles, the buzz has grown.
The reason becomes clear when you take a closer look at some of the forms of E. wushanense, a plant Probst calls the “holy grail” of epimediums. In the wild, E. wushanense is typically three feet tall, and produces hundreds of bronze-yellow blossoms in a single burst in spring—in other words, a lovely and distinctive plant. On a trip to eastern Sichuan in 2001, however, Probst hit the epimedium jackpot. On one mountain he came across a group of E. wushanense that had two bracts on the pedicel behind each flower. Since each bract produces a flower, that meant that, in a few weeks, there would be two more flowers for each original flower, plus there would eventually be two more bracts behind each of the second-string flowers. One plant in the group even produced four extra bracts per pedicel. You do the math. “I… knew at the time,” Probst writes in his chatty, tantalizing catalog, “that I probably would never find anything that exceeded it in the rest of my life.”
TREASURES FROM THE EAST
At this point I’m beginning to understand why Probst is so intoxicated with the possibilities offered by the Chinese species. China, it turns out—and specifically eastern Sichuan—is the center of distribution for the genus. In 1938, the year that the renowned botanist William T. Stearn wrote the first version of his then-definitive monograph on epimediums (an updated version was published last summer by Timber Press), only 13 species were known to exist in China. Since that time, 26 new species have been discovered there—21 of them since 1990. Epimedium wushanense is, understandably, one of the stars, but there are other gems as well: for example, a tiny species new to science (its closest relative appears to be E. campanulatum), which is a mere two and a half inches high, with cup-shaped, butter-yellow flowers; and E. fargesii, whose flowers, borne on foot-long panicles, look like three-quarter-inch lavender stars, but on closer inspection turn out to be bicolor, with white or lavender sepals and dark purple spurs. Nor are flowers the only attraction. Epimedium ilicifolium, a species discovered in 1998, bears spiny, narrow, evergreen leaflets reminiscent of some hollies (ilicifolium means “holly-leaved”). Other species have foliage that is rounded, heart-shaped, or elongated, smooth- or spiny-edged; matte or glossy; and rimmed or splotched with red or purple. In short, the Chinese epimediums constitute a large basket of genetic goodies, which is precisely why they appeal to Probst. He has plans.
Opposite: Like many Chinese epimediums, E. stellatulum is highly variable; the starry flowers are usually white, but the width of the leaflets can vary from medium to extremely narrow. Above right: A Japanese selection of E. ?youngianum. Right: An herbarium sheet showing a pressed specimenof an extremely narrow-leaved Chinese species new to science—and as yet unnamed.
Caring for Epimediums
EPIMEDIUMS ARE FUNDAMENTALLY SHADE LOVERS, although the degree of shade they need will vary depending on where you live (less in the cool Pacific Northwest; more in Denver). In his Massachusetts garden, Probst tries to make sure that his plants get no more than five hours of direct sun a day; any more causes leaf scorch. That said, epimediums will bloom most heavily and increase most rapidly where they get at least a couple of hours of direct or bright indirect sun.
Epimediums will grow in most soils, provided they are well drained and reasonably moisture-retentive. While epimediums are moderately drought tolerant once established, they must be kept well-watered during their critical first year. Some of the more drought-tolerant species and hybrids are: E. alpinum, E. xcantabrigiense, E. xperralchicum, E. pinnatum subsp, colchicum, E. pubigerum, E. xrubrum, E. xversicolor, and E. xwarleyense.
Although epimediums can be planted and divided in spring, Probst says that fall planting and division usually yield better results. Plants that go into the ground in fall should be mulched to prevent heaving during the winter. Probst considers the epimediums he offers to be fully hardy through USDA Zone 5. –T.F.
I’ve been breeding them for about seven years now,” he says. “These plants have amazing potential. The more I’ve found out about them, the more herbarium specimens I’ve looked at, the more excited I’ve become. The Chinese epimediums have characteristics I haven’t seen anywhere else. And with all the new species being discovered…” His voice trails off as he contemplates what glories the future may hold. Besides their genetic richness, epimediums have another advantage over other shade-loving perennials—their ease of culture. “Of all the different perennials I’ve grown,” Probst says, “they’re the one group where if you don’t divide them, you don’t water them, you don’t fertilize them, they just keep going. Whereas with plants like astilbes or pulmonarias, if you don’t divide them every three years, they either rot and die or they just stop blooming.” (See “Caring for Epimediums,” opposite.)
THE NEW HYBRIDS
Probst’s breeding program has already borne promising fruit. One of the most attractive is a cross between E. davidii and E. platypetalum, two yellow-flowered species. Probst likes to make the same cross using different clones of the parent species in order to increase the odds of getting truly outstanding offspring. Probst points to one of the seedlings and says, “See how much better this is? It’s much more floriferous.” And so it is; in fact, it puts its nearby siblings to shame. For Probst, this heavy-blooming hybrid is a vindication of his practice of collecting multiple clones of each species, which enables him to maximize the genetic resources at his disposal. Even within a single species, Probst tells me, there’s a huge amount of variation. For example, while most individual clones of E. davidii have medium yellow flowers, some, like Probst’s prized ‘Ghostly Desire’, are pale butter yellow; and while most clones bloom primarily in spring, there are others that bloom and produce new foliage continuously throughout the summer (provided they get enough water). By having a large pool of desirable characteristics from which to choose, Probst has a much greater chance of creating top-notch hybrids. As he says of his efforts, “We make sure they’re really good plants before they go out. It might not be to our financial advantage in the short run, but in the long run people will trust what we’re doing.”
Opposite: Named in 1991, the Chinese E. calcaratum is still rare in cultivation. The relatively large, bell-shaped flowers are unusual in that they consist almost entirely of petals; the sepals appear only as small, dark brown wings. The emerging foliage is blackish brown. Above and below: Different populations of Epimedium davidii vary greatly in their vigor and floriferousness.
Although Probst’s collecting began as a purely personal interest, it has recently taken on a wider scope. “One of my goals,” he says, “in obtaining blocks of the same species from different locations was to learn about the variation within the genus. But an equally important goal was to preserve them here for the horticultural and scientific communities. And I think the best way to do that is to propagate and distribute them.” Probst’s mission has gained urgency from the rapidity with which the plants” habitats are disappearing. “I visited one area in China in the fall of 2000,” Probst recalls, “where there were lots of epimediums. When I went back in the spring of 2001, the local farmers had gone through and dug up everything and just trashed it all on the side. But at least they’re growing food; we do the same thing and put up strip malls.”
THEME AND VARIATIONS
Even though the new Chinese epimediums are the cream of Probst’s collection, they are by no means the only representatives of the genus at Garden Vision. There are also hundreds of the more (or less) familiar species and cultivars—clones of E. grandiflorum, E. Xversicolor, and E. Xyoungianum, for example—all of them, as Probst is quick to point out, correctly identified and labeled. As his catalog proclaims, “Be assured that when you order E. grandiflorum ‘Silver Queen” from this catalog, you will get the true cultivar and not some other variety incorrectly labeled (which I have received so many times myself).” During my visit, my eye was caught by one of Probst’s new E. Xyoungianum selections, ‘Be My Valentine’. A compact, six-inch plant, its flowers had glowing cherry-red inner sepals, white petals flushed with rose, and short white spurs. Seconds later I was trying to figure out where I’d put it in my garden. Or did I want one of the E. davidii clones, or maybe E. fargesii? Some friends of mine in Seattle, both of them superb plantsmen and garden designers, confided in me recently that they think epimediums are going to be the new “it” plant. If that’s true—and it wouldn’t surprise me—then Darrell Probst has about as much “it” as any gardener could wish for, and fortunately, he’s sharing it with the rest of us.
Dividing an Epimedium
1 Dig up the plant you’re going to divide.
2 Remove the clump gently—try to keep the root system as intact as possible.
3 Using a hose, rinse the soil off the roots. Make sure the water pressure isn’t too high.
4 With a pair of sharp secateurs, cut through the rhizome.
5 Each division should have some foliage and at least a two-inch section of rhizome. Replant in a shady spot in well-drained, moisture-retentive soil. See “Caring for Epimediums,” page 50, for further information.
If You Go
Garden Vision nursery is not usually open to the public, but does hold Open Nursery Weekends during peak bloom time in mid-May. Call 978–928–4808 for dates, hours, and directions. For a copy of the Garden Vision catalog, write Garden Vision, 63 Williamsville Road, Hubbardston, MA 01452, or e-mail darrellpro@earthlink net.