Growing Hardy Orchids in the Pacific Northwest

By: Lee Neff

Lee Neff is a garden writer and occasional contributor to Pacific Horticulture. She lives and gardens in Kingston, Washington, where…

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A large patch of Cypripedium  formosanum thriving at Heronswood. Photographs by Lynne Harrison

A large patch of Cypripedium formosanum thriving at Heronswood. Photographs by Lynne Harrison

Growing hardy orchids is not for gardeners unwilling to take absurd and sometimes costly risks. In fact, one must steel oneself for either quick or lingering death and accept responsibility for both. Still, the glamour and pride of humbly sharing with an astonished visitor blooming orchids—orchids that live outside year ’round—make it possible to damn the cost and accept such loss. At times, it is best just to embrace one’s annoying need to boast and move ahead. After all, human beings may have collected orchids for over 4000 years, and there are plenty of indoor gardeners whose orchid collections thrive without a drop of humility.

My own infatuation with growing hardy orchids began when I visited my sister Penny in Western Massachusetts one May, years ago. On the hill where she lives, in the pine woodland around her home, there were hundreds of native pink lady’s slippers (Cypripedium acaule) in bloom, their dark pink pouches rising only a few inches above the deep pine duff. As sisters, Penny and I have wisely cultivated different talents; the fact that she, little interested in gardening, had such a display of glamorous, enchanting lady’s slippers filled me with envy. It occurred to me at the time, to dig up a few plants and fly them back to Seattle, but to my modest credit, I did not succumb to that temptation.

This elegant lady’s slipper seems to have been introduced into gardens in the eighteenth century; yet, it is still considered one of the most difficult cypripediums to grow. Most of my early inquiries into growing it in this region resulted in either disappointing doubts or tales of hope that ultimately dwindled into failure, so I have not tried to grow C. acaule. A few others are growing it successfully in this region. Steve Doonan, who grows pots and pots of cypripediums from tiny seedlings, says that success with C. acaule depends upon giving it abundant light and moisture as well as an extremely well drained, peaty, highly acidic growing medium (pH of 4.5 to 5).

Instead, I kept my eyes open for other orchids to try, and, over the years, without belaboring the deaths alluded to above, I have begun to collect a number of orchids that have lived long enough in my garden to allow me to state that I “grow” them.

Showy lady’s slipper (Cypripedium reginae)

Showy lady’s slipper (Cypripedium reginae)

Cypripedium

In the genus Cypripedium, I have tried three species: showy lady’s slipper (C. reginae), large yellow lady’s slipper (C. parviflorum var. pubescens), and C. formosanum. All cypripediums are deciduous and hail from North and Central America, Europe and Asia. I purchased a plant of large yellow lady’s slipper (until recently included within C. calceolus) at a Washington Park Arboretum plant sale six years ago. I know just how long I have had it, because, each year, it adds one more stalk of flowers to its expanding clump. Native to eastern North America, this species has sepals and petals of greenish yellow, streaked with brown, rather than the dark maroon sepals and petals of its European cousin, C. calceolus.

Both of these lady’s slippers are among those reputedly easiest to grow, a list that includes the other two species I have tried (showy lady’s slipper and Cypripedium formosanum), as well as C. kentuckiense and C. henryi, which I have not attempted yet. Hand-carried back from its native American Midwest eight or nine years ago, my plant of showy lady’s slipper flowered well enough during its first two years in my garden that I believed it was “settling in nicely.” But, in subsequent years, it dwindled, and I fear may now have to be counted among the deceased. Originally planted in a brightly lit patch of woodland, it was increasingly shaded as the woodland matured; when I try C. reginae again, I will remember that it requires much more light to grow and flower well.

A plant of Cypripedium formosanum, recently obtained from Heronswood Nursery, looks as if it is happy, but I am watching it carefully for signs of sulking. About this species, Dan Hinkley explains: “Cypripedium formosanum is remarkable in our climate. We find that dividing it regularly is the key. Also, replenish the soil with organic matter at the time of division.” Hinkley provides lots of fertilizer; Helen Dillon, gardening in Dublin, Ireland, says she is successful with this species by not fertilizing it. The large patch of C. formosanum thriving at Heronswood might incline one toward Hinkley’s approach. In my garden, fertilizing usually consists of an annual dressing of good compost. And, although C. parviflorum var. pubescens has grown consistently with that provision, a more lavish diet might produce more enthusiastic flowering for C. formosanum.

Richie Steffen grows a number of cypripediums in pots at the Miller Botanical Garden in Seattle and offers the following formula for success: moist, well-drained, rich soil; lots of leaf-mold; a little grit or gravel mixed in with the soil; bright light (even good, morning sun); regular fertilization; and no competition. In other words, these orchids enjoy all the coddling we can give them. In the case of my diminished showy lady’s slipper, less sun than ideal, less water than ideal, and perhaps less sweet lime (calcium carbonate) than ideal may have conspired to dampen its enthusiasm. Hinkley also believes that the species needs more heat than we can provide; “it blossoms for us but does not sing.”

Of course, you could just try growing all cypripediums in pots, as Doonan and Steffen do. And why not try the West coast natives, mountain lady’s slipper (C. montanum) and C. californicum? Doonan obtains tiny mail-order seedlings and grows them in wide clay pots, with the bottoms knocked out to provide perfect drainage but with shade cloth placed in the bottom of the pots to hold in the soil. His recipe for success includes planting these babies an inch deep in sandy, gritty soil and protecting them from extra water by keeping them under plastic in winter. Guarding against slugs and other critters is also critical. With lots of luck, careful observation, conscientious tending, and prayer, you might end up with a choir!

A vigorous hybrid spotted orchid (Dactylorhiza x grandis) flowering against Aruncus dioicus in the gardens at Heronswood Nursery

A vigorous hybrid spotted orchid (Dactylorhiza x grandis) flowering against Aruncus dioicus in the gardens at Heronswood Nursery

The modest spikes of common spotted orchid (Dactylorhiza fuchsii) against the bold leaves of a corn lily (Veratrum)

The modest spikes of common spotted orchid (Dactylorhiza fuchsii) against the bold leaves of a corn lily (Veratrum)

Dactylorhiza

Deciduous orchids found in boggy grassland habitats in Asia, North America and Europe, Dactylorhiza species flower in tints of pink, from pale to fuchsia, in late spring or early summer; many have attractive dark green leaves with rich maroon spots. Having grown and divided common spotted orchid (D. fuchsii) for over ten years, I feel confident in proclaiming that it has thrived in my garden in partial shade, with an annual dose of compost and infrequent summer water. It divides easily in fall or early spring and makes a welcome gift. However, Hinkley comments on Dactylorhiza, in general, at Heronswood: “We find they need to be moved to new places in the garden on a regular basis, as they seem to begin declining if left in the same place, even if we replenish the soil at the time of division (which they also respond to).” With new species now more available for purchase, success with one of these lovely orchids can only encourage us to try others.

Epipactis gigantea ‘Serpentine Night’ displays purplish foliage and curiously colored flowers

Epipactis gigantea ‘Serpentine Night’ displays purplish foliage and curiously colored flowers

Epipactis

My patch of dactylorhizas is located near an expanding colony of Epipactis gigantea ‘Serpentine Night’. This is a selection of the stream orchid (E. gigantea) that grows wild from British Columbia south to California and east to South Dakota, Utah and Texas; discovered by Roger Raiche on the serpentine site known as The Cedars, north of San Francisco, its dark red foliage is a good contrast to that of the Dactylorhiza. Not as small as the tiny, individual Dactylorhiza blossoms, the blooms of the low-growing Epipactis are a remarkable combination of greenish yellow, purple, and orange brown. In my garden, this genus has done well as long as it has received enough light. A patch of E. gigantea planted in deeper shade has grown much more slowly and flowered with less enthusiasm.

Calanthe x Kozu hybrids (C. discolor x C. izu-insularis)

Calanthe x Kozu hybrids (C. discolor x C. izu-insularis)

Calanthe

About five years ago, I purchased two Calanthe x Kozu hybrids (C. discolor x C. izu-insularis) from a local nursery. These Japanese hybrids were not in flower, and their evergreen foliage did not immediately recommend them. But it was impossible to resist orchids that were reputedly not too difficult to grow. I planted them in bright shade and moist soil. One has stood up and cheered; the other just putters along. When their leaves get a bit tatty looking, I remove the outer ones, which may not do them much good, but seems not to have done them great harm. These Calanthe hybrids, and others from Japan that have been offered more recently, come in a wide variety of colors—red, white, pink, or yellow—reflecting the species used in their creation. Part of their charm is their variability.

Several years ago, I added Calanthe discolor and C. tricarinata to the same garden area that had nurtured the Kozu hybrids. Once again, I have had mixed success. Calanthe discolor, with its small wine red and white flowers, has prospered, whereas C. tricarinata, which promises stunning yellow green flowers with reddish brown lips, has merely limped along. Perhaps the calanthes that have been less successful here want a bit more light or a bit more fertilizer, as Steffen suggests for cypripediums.

Pleione formosana, from eastern China and Taiwan, may be only barely hardy in many parts of the Pacific Northwest

Pleione formosana, from eastern China and Taiwan, may be only barely hardy in many parts of the Pacific Northwest

Pleione

Looking, as Hinkley states, “like bright magenta cautleyas on the woodland floor,” Pleione formosana and its hybrids have proven to be less picky than feared in my garden. Reputedly interested in regular water in the summer and dry conditions in winter, they have adjusted to infrequent water in the summer and the shelter of a large, old camellia for winter protection. From Taiwan and mainland China, these small plants, which grow from greenish, brown, or black pseudobulbs, produce impossibly large flowers in shades of pink and white. Of borderline hardiness in my garden near Lake Washington, they seem to need greater winter protection at higher or cooler elevations.

An eastern American native  orchid, Spiranthes cernua var. odorata

An eastern American native orchid, Spiranthes cernua var. odorata

Spiranthes

Although it languished a year or two before flowering, the East Coast native, Spiranthes cernua var. odorata, has now bloomed for two years in a lightly shaded garden spot that receives regular water. Reputed to be the southern form of S. cernua (which may also be S. odorata), this variety grows from Virginia to Florida and is highly recommended by Plant Delights Nursery (of Raleigh, North Carolina) as an easy-to-grow garden orchid. It grows by underground rhizomes into sizeable clumps in damp spots in the wild. In addition to its pleasant fragrance, it has pristine white blossoms and September flowering to recommend it.

Chinese ground orchid (Bletilla striata) has never thrived in the author’s garden, but does so elsewhere in the Pacific Northwest and in Northern California

Chinese ground orchid (Bletilla striata) has never thrived in the author’s garden, but does so elsewhere in the Pacific Northwest and in Northern California

Failures

Sad to say, I have not yet been successful with Calypso bulbosa, Goodyera oblongifolia, Piperia elegans, or Chinese ground orchid (Bletilla striata), even though the last named is reputedly one of the easiest hardy orchids to grow, and the first three are native to this part of North America. Each of these species requires something that I have not provided—a grittier soil or more regular water, perhaps association with a particular mycorrhiza, or better protection from slugs.

Out there, somewhere, among the more than 30,000 species of orchid in this world, may be other species that would love to grow in Northwest gardens. The challenge is to find them—grown from seed or tissue culture, since collecting wild plants is in most instances illegal and, if not, should be. With persistence, we may find more of these bewitching plants to grow and to brag about; with care, we may ensure that these exotic beauties are enjoyed by gardeners and collectors for another 4000 years.