Caring For Native American Lady Slipper Orchids

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Q. I have a small—very small—patch of Lady Slippers growing in my semi-shady garden that I'd like to encourage. What should I do to make them feel at home; even multiply? Thanks!

---Julia in Berwyn, PA

A. Julia's question immediately made me think of Dr. Bill Mathis: author of "The Gardener's Guide to Growing Hardy Perennial Orchids", owner of The Wild Orchid Company (a Pennsylvania-based enterprise that supplies 100% cultivated versions of the fragile treasures; none collected from the wild), and most importantly, a lifelong lover of these great plants.

His response to Julia's question? "What kind of Lady Slipper? There are several different varieties, and they all require different conditions." Luckily, the subject line of Julia's email specified yellow Lady Slippers. "That's good", he replied; "they're the easiest of the native terrestrial orchids to care for."

But before we get to that care, a short orchid tutorial. Most of the world's orchids are epiphytes; plants that cling to things like trees with big strong aerial roots. They are not parasites; they take no nutrients from the plants they cling to—they just hang onto them. This is why most houseplant orchids are sold with their roots nestled in big chunks of bark; the vast majority of epiphyte-type orchids would die if their roots were smothered in any kind of soil.

But a small percentage of the world's orchids have evolved to naturally grow in soil (although Dr. Mathis stresses that the roots of these orchids look much the same as those of the tree-hugging epiphytes, and share a similar need for exposure to air and superb drainage). These "terrestrial" orchids occur worldwide, with a nice handful of species native to the U.S. Of these American natives, the best known are the various Lady Slipper orchids, of which there are numerous varieties, with common names that include yellow, pink, 'showy' and 'Kentucky' Lady Slippers.

Dr. Mathis explains that the basic requirements for yellow Lady Slippers are excellent drainage and some shade during the day. How much shade depends on where they're growing; they can take almost full sun at the Northern limits of their range (USDA Zone 4), need dappled shade or semi-shade in the middle of their range (Zones 5 and 6), and require almost deep shade at their far Southern extreme (around Zone 7). "They won't survive South of that, unless you're up in the mountains or some other cool microclimate," he explains; "they just can't take the heat.

"Now, if these yellow Lady Slippers just 'showed up' in the garden, don't change a thing," insists Dr. Mathis, explaining that the seeds of these orchids are so small they can blow into new areas on a windy day from a natural site, or be carried to new sites by wildlife. "If such seeds did make their way there, germinated, and the plants grew on their own, the site is already perfect", he explains. "Just keep chemical fertilizers away from them; these Lady Slippers are very low-nutrient plants, and an otherwise 'normal' application of something like Miracle-Gro or Osmocote could kill them.

"No matter how they got there, it's a good idea to water them during Spring and Summer droughts", he continues, explaining that "they need excellent drainage, but long periods of dryness can kill them." He adds that the shredded leaf mulch that I {quote} 'love so much' can do double duty here—"as a light mulch over top of the plants for winter protection and around them during the growing season to retain soil moisture and keep weeds at bay.

"Now, if she bought the plants, I suggest she deadhead the flowers as soon as they start to fade to prevent seed production", he continues. "The act of creating those tiny seeds sucks a lot of energy out of the plant, and the odds are a million to one against those seeds germinating at a created site, no matter how ideal the site may be for adult plants.

"BUT if the plants did just 'show up', it means that the conditions are perfect for seed germination," he explains. "So I'd still deadhead the majority of the flowers, but I would also allow a few to progress and produce seed. And I'd hand pollinate them with something like a flat toothpick or a Q-Tip to insure a good seed set. Then be patient; the seed germinates pretty quickly, but the young plants will be 'subterranial' for several years before you see any above-ground leaves."

This need for the seed to fall in exactly the right kind of place, with exactly the right kind of symbiotic soil organisms naturally present, is one of the many reasons you should never take any native orchids from the wild, he adds. "Left undisturbed, a native colony will self-seed and grow over time. But if you take those plants to a new location, the plants themselves often die; and even if they don't, no new seeds will ever germinate there. And there are plenty of sources for gardeners to obtain legal, ethical, healthy, ready-to-plant cultivated Lady Slippers; there's no need to take plants from the wild, and millions of reasons not to."