Introduction to Hardy Orchids for the Perennial Garden
Everybody knows and loves the exotic, tropical orchids (e.g., phalaenopsis, and cattleya), but wouldn't it be nice to have an orchid that lives outside in temperate zones? It might surprise you to know that there are many beautiful terrestrial orchids for temperate zones 5-9 that are actually very easy to grow such as bletilla and calanthe. Other genera worth experimenting with in temperate climates include aplectrum, pogonia, calopogon, cephalanthera, cymbidium, epipactis, goodyera, habenaria, pleione, spiranthes, and tipularia. We will not address epiphytic (non-soil growing) orchids in this article and cypripediums (hardy lady slipper orchids) are covered in a separate article.
We at Plant Delights Nursery and Juniper Level Botanic Gardens grow many wonderful and rare orchids for the Southeast. We have 171 taxa of hardy orchids growing in our garden and are always pushing the boundaries and trying out species to determine if they can survive our North Carolina summers and winters.
History of the Cultivation and Collection of Orchids
Orchids belong to a huge plant family called Orchidaceae. There are over 880 genera and 30,000 species in the family. Almost 10% of all known plants in the world are orchids...and you thought they were rare! Based on the complexity of their flower morphology and highly specialized habitats and life cycles, orchids are considered to be the most highly evolved of the monocots (plants that germinate with only one leaf). The name Orchidaceae is derived from one of its genera (orchis), which in turn is derived from the Greek word "orkhis", meaning testicle, as orchis species produce a pair of bulbs the size and shape of dog testicles...I'm not making this up! Gardeners have flocked to this charismatic group and horticulturists have bred or selected over 100,000 registered hybrids and cultivars of orchids and possibly four times as many unregistered hybrids.
Orchids are widespread on every continent except for Antarctica. North America has at least 20 native genera of cold tolerant orchids, and our home state of North Carolina is home to 60 native orchid species. Orchids grow in every habitat except for deserts and on glaciers, with 90% of the orchid genera being tropical.
Orchids have been coveted and grown for centuries. Over 2500 years ago the Chinese philosopher, Confucius, grew orchids and wrote poetry and music about them. The earliest written music that still exists today is Confucius' Youlan orThe Solitary Orchid. About 2200 years ago, the Greek Father of Botany, Theophrastus, was the first to use the term "orchid" in his book, Historia de Plantis (aka Enquiry into Plants). Two thousand years ago, the Greek botanist Dioscorides wrote a medical book, Materia Medica, describing how to use orchids as an aphrodisiac. In medieval Europe, a philosophy known as the "doctrine of signatures" held that a plant's appearance indicated how mankind should use it; thus, orchids became widely used to enhance male sexual prowess. North American orchids made their way to Europe on the ships of Columbus and Cortez during the Age of Discovery. In 1885, The Royal Horticultural Society in England started the first Orchid Society and in 1921, the American Orchid Society formed.
Orchid collecting remained small scale until the nineteenth century when an orchid frenzy erupted in Europe. The orchid obsession was fueled in part by the 1851 publication of The Orchid Grower's Manual by B.S. Williams which taught growers how to properly care for and propagate orchids. The Victorian era of orchid madness is known as theorchidelirium, and it rivaled the Dutch tulip mania of the 1500s. Wealthy orchid fanatics sent collectors and explorers all over the world to bring back rare and beautiful species to be sold at auction for outrageous prices. Collectors mounted expensive expeditions that were shrouded in secrecy, misinformation, danger and violence. Today, our obsession with orchids is supported by a billion-dollar industry that propagates massive numbers in tissue culture laboratories.
Orchids are primarily used as ornamental plants with a few exceptions. The spice vanilla is derived from the seed pods of the orchid genus vanilla. The genus orchis produces rhizomes that are ground into a powder called salep and used as flour. Occasionally, orchid flowers are used as a salad garnish in fancy restaurants and orchids are also popular cut flowers. Their ethnobotanical applications include their use as an aphrodisiac (orchis bulbs), to staunch blood flow (bletilla rhizomes), to reduce fertility in women (ansellia), and as a sedative and anti-anxiety medicine (cypripedium rhizomes).
Orchid Anatomy and Morphology
Hardy orchids are generally herbaceous perennials that form a small clump. Although many tropical orchids are epiphytic (live in tree branches) or lithophytic (live in the cracks of rocks), most winter hardy orchids are terrestrial and live in soil. Orchid roots tend to be short, fleshy, thick, fragile, and occur near the soil surface. Some species produce specialized thick underground stems called rhizomes that spread out and spawn new plantlets near the parent. Other species produce structures that may look like a round bulb, or a flattened corm. The rhizomes, bulbs, and corms are all referred to as pseudobulbs. Pseudobulbs are thick fleshy stems that may form under or above the ground. New leaves and flowers arise from the pseudobulbs for one growing season. After one season, the leafless pseudobulbs are then called backbulbs. The backbulbs remain attached to the crown of the plant for a few years to provide energy, but they eventually deteriorate.
How to Grow Orchids in Your Garden
Most hardy orchids are woodland, grassland or forest edge species, with only a few tolerating direct sun. As a general rule, hardy orchids like well-drained, cool, moist soils. The combination of well-drained and moist soil often confuses gardeners. Imagine a sponge that has been squeezed out. It is both well drained (lots of air in it) and moist (lots of water in it). In order to provide well-drained, cool, moist soil it is best to mix compost with your native soil. We recommend a nutrient rich soil with a pH between 6.2 and 6.5, in which not only orchids, but most garden plants tend to thrive. As long as the soil is nutritionally balanced, no additional fertilizers should be needed unless directed by a soil test. If needed, use an all organic blend is recommended.
Once your bed is finished, carefully plant your hardy orchid so that you do not break any of the fragile roots. Spread the roots out as widely as possible. It is best if the crown of the plant is at ground level or just slightly below since planting it too deep invites crown rot. Provide a covering of mulch to keep in moisture and keep the soil cool. If your soil is organically active and not unbalanced by chemicals, slugs and snails should be kept in check.
Hardy orchids require a period of cold winter vernalization, but the roots do not like to freeze and thaw repeatedly. Place 2-4 inches of mulch on the bed after the first hard freeze to insulate and even out the temperature swings. Keep other more aggressive plants that may compete for nutrients away from hardy orchids. Small or medium sized hostas are good companion plants, as well as clump forming ferns, epimediums, helleborus, cyclamen, trillium and other woodland dwellers. Since orchids are usually shallow rooted, do not use hoes for weed elimination.
How to Propagate Orchids
Cypripedium, bletilla, calanthe, and cymbidium will all form clumps if they are happy. While the clumps do not need regular division, they can be divided to produce more plants. The clumps should be carefully dug so as to not damage the very fragile fleshy roots. The new plantlets can be teased apart or cut apart with a knife.
Rhizomes (if produced) can be cut with a knife as along as there is at least one healthy bud per cutting. Although this can be done in early summer, my favorite time is in the winter...assuming the ground in your area isn't frozen.
Orchid backbulbs have dormant buds that will become active again when separated from the pseudobulb and planted. Backbulb propagation works best for aplectrum, bletilla, calanthe, cymbidium, calopogon, and tipularia. Be patient, since it may take a couple of seasons to produce a meaningful sized plant.
It is extremely difficult to grow orchids from seed, not only because the seeds are the size of dust, but because most seeds have no endosperm and most seedlings do not form cotyledons. In the wild, orchids require a specific symbiotic mycorrhizal fungus to provide sugars, hormones, and other growth factors to the seedling until it is large enough to survive on its own. Orchids can be grown from seed without the fungus (asymbiotically) in sterile tissue culture labs today thanks to a specialized process developed in 1922 by Dr. Lewis Knudson of Cornell University.
This process starts with seed pods that have been allowed to ripen for several months until they are three fourths ripe. Immature pods (and seeds) are preferred because the mature seeds are dormant and contain germination inhibitors that require a cold period to overcome. The pods are surface sterilized in bleach then flamed with alcohol. The pods are cut open with a sterile scalpel, and scraped to remove the dust-like seeds. The seeds are surface sterilized and placed into jars containing a special growth mix of agar, sugars, hormones, and nutrients (the "Knudsen formula"). Bletillas grown from seed can flower in as little as 3 years, but most other hardy orchids take 6-8 years from seed to flower. Now you understand why hardy orchids can be so pricey!
Bletilla (Chinese Ground Orchid)
The name Bletilla literally means "little Bletia" which is a New World orchid genus that it resembles. In turn, bletia is named for a Spanish botanist and apothecary, Don Luis Blet. Bletilla goes by the common name Ground Orchid.
In climates where they are winter hardy, Bletilla is the easiest hardy orchid to start with because it is very adaptable to a wide range of environments. The genus contains 8 species that are native to Asia. Three species, the pink flowered Bletilla formosana, the yellow flowered Bletilla ochracea and rose-purple flowered Bletilla striata are common in horticulture. Mature bletilla form a series of inflorescences (racemes) for up to 10 weeks in the spring or early summer. Each inflorescence arises at the tip of a stem and has 3-10, 1.5" wide, nodding florets.
Bletilla also have shallowly pleated (plicate), narrow leaves that are attractive even when the plant is not in flower. The plants are deciduous and grow to about 1.5' tall. In their native environment, they grow in dappled shade under a canopy of tall grasses but they adapt well to a wide range of woodland sites. In the garden, bletilla prefer evenly moist, well-drained soils and a position in half-day sun or light shade. Bletilla are fairly drought tolerant, but the growth rate slows dramatically when they aren't kept moist. When they are growing well, they quickly form large clumps.
At the northern end of their hardiness range bletilla need a winter covering of mulch to protect the roots. At the southern end of their range they may emerge early during warm spells, and are thus susceptible to late freezes. When possible, plant them in a cooler spot in your garden to delay their spring emergence.
There are over 40 cultivars and hybrids of Bletilla that have been selected for flower color or variegated leaves. Breeders are focusing on increasing flower size and the number of florets per inflorescence, creating plants with more outward facing flowers, and improving the color of the white flowered forms. The foremost breeder of Bletilla is Richard Evenden of Spalding, UK, who is responsible for most of the hybrids. Other prominent breeders include Dr. William Mathis of Wild Orchid Co. of Carversville, Pennsylvania and the folks at Jewell Orchids of Colbert, Georgia. Several Japanese cultivars have been imported to the US market and are becoming more widely available.
List of Bletilla Species
Bletilla formosana (Taiwan Ground Orchid)Bletilla formosana hails from Taiwan, Japan's Ryuku Islands, and the Chinese provinces of Gansu, Guangxi, Guizhou, Jiangxi, Shaanxi, Xizang, and Yunnan from 2000'- 9500' elevation, where it can be found in grasslands and evergreen forests. The linear green leaves are topped in late spring and early summer with 18-24" tall flower spikes, ending in 1-6 pale pink flowers. Most of the Bletilla formosana in commerce isn't particularly winter hardy, but based on its natural range, there are certainly some high elevation forms that need to be brought into cultivation and should be much more winter hardy. (Hardiness Zone 8-10, at least)
Bletilla ochracea (Golden Chinese Ground Orchid) Bletilla ochracea hails from evergreen forests and grasslands from 1000'- 7500' elevation in Vietnam and the Chinese provinces of Gansu, Guangxi, Guizhou, Henan, Hubei, Hunan, Shaanxi, Sichuan, and Yunnan. Similar to the more common Bletilla striata, these counterparts are a bit more finicky in the garden. Growing much slower than its relatives, Bletilla ochracea prefers a moist but well-drained woodland soil. In spring, the stalks emerge from the underground pseudobulb each bearing two long, pleated green leaves. In early to mid-May in NC, the clumps are topped with 18" tall stalks of 1" light yellow flowers with a lip that can range from light lavender to dark yellow. I have read reports of Zone 5 hardiness, but have yet to see confirmed temperature data of plants withstanding -20F without snow cover. (Hardiness Zone 7b-8)
Bletilla ochracea 'Chinese Butterfly' Strain (Chinese Butterfly Ground Orchid) The 20" wispy flower stalks emerge from below-ground pseudobulbs, and top the iris-like pleated leaves in June. Each flower stalk is topped with 3-5 small, creamy yellow flowers, each highlighted with a purple and yellow speckled lip. Bletilla ochracea is a slow grower, more finicky than Bletilla striata...moist rich soil and morning sun or high, filtered, light shade are best. This Linda Guy introduction is from Sichuan, China, and seems more vigorous than other Bletilla ochracea that we have tried in the past. (Hardiness Zone 7b-8 at least)
Bletilla striata (Chinese Ground Orchid) Bletilla striata has a wide native distribution that includes Japan, Korea, Burma, and the Chinese Provinces of Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Sichuan, and Zhejiang, where it can be found between 300' and 10,000' elevation in grasslands and evergreen forests. This hardy and very easy-to-grow terrestrial orchid has upright, heavily textured, iris-like 10" long by 1" wide green leaves and forms a slowly spreading clump. In early spring, stalks to 15" tall of very small Cattleya-like lavender flowers are held atop the foliage. The rhizomes spread slowly and eventually form a nice mass to 2' wide in 5 years. Bletilla striata grows best in moist to damp soils, although it is amazingly drought tolerant. We get many reports of Zone 5 hardiness, but cannot confirm its survivability at -20F without snow cover. (Hardiness Zone 6-9)
Bletilla striata 'Alba' (White Chinese Ground Orchid) This is the solid white-flowered form of the hardy Bletilla striata orchid. The two deeply veined, medium-green leaves arise in early spring, followed immediately by the narrow flower spike emerging between them. In early May in NC, the 15" spike is clothed with 1" pure white flowers. When grown from seed, seedlings often have a purple flush to the petals. Under good conditions, expect a 2' wide patch in 5 years. (Hardiness Zone 6-9)
Bletilla striata 'Albostriata' (White Striped Chinese Ground Orchid) This is one of a few white-edged forms of the commonly grown ground orchid. Two opposite, iris-like, pleated leaves emerge from each pseudobulb in early spring. As the leaves emerge edged in a narrow band of white, the flower spike arises through the center and then opens a few inches above the foliage. The flowers are rich purple in early spring, April for us. (Hardiness Zone 6-9)
Bletilla striata 'Big Bob' (Big Bob Chinese Ground Orchid) This selection with William Mathias of the Wild Orchid Company has a much taller flower spike that reportedly tops 36" tall, although our plants and those of others in the Southeast have never produced flower spikes taller than 18". The 2" rose-lavender blooms with white and dark lavender highlights are produced in early to mid-spring. (Hardiness Zone 6-9)
Bletilla striata 'First Kiss' (First Kiss Chinese Ground Orchid) There are a number of white-edged leaf forms of the hardy orchid, most without valid names. Our form, Bletilla 'First Kiss', has the same deeply-veined, long green leaves that emerge from a central stem in late March. In late April in NC, the stems are topped with small white orchid-like flowers with a flush of purple on the lip. This vigorous grower will quickly make a colony when grown in rich, moist soil. In the South, a bit of shade is helpful, while full sun farther north makes a better floral show. (Hardiness Zone 6-9)
Bletilla striata 'Gotemba Stripes' (Gotemba Stripes Chinese Ground Orchid)(Gotemba Stripes Chinese Ground Orchid) This Japanese selection of Bletilla striata boasts yellow striped foliage, topped in spring with typical spikes of lavender flowers. Bletilla striata 'Gotemba Stripes' is a much slower grower that the other cultivars. (Hardiness Zone 6-9)
Bletilla striata 'Innocence' (Innocence Chinese Ground Orchid) Bletilla striata 'Innocence' is a seedling selection from Nebraska's Bluebird Nursery that produces spikes of white flowers with a light lavender lip. (Hardiness Zone 6-9)
Bletilla striata 'Junpaku' (Junpaku Chinese Ground Orchid) (Junpaku Chinese Ground Orchid) More than likely, this is the correct name for the cultivar Bletilla striata 'Alba', which has pure white flowers. (Hardiness Zone 6-9)
Bletilla striata 'Kuchibeni' (Kuchibeni Chinese Ground Orchid) This hard to find but easy-to-grow cultivar from Japan is distinguished by its two-toned flowers. The upper part of the flower is white, while the lip is a contrasting purple. The foliage and growth habit are the same as in the species. (Hardiness Zone 6-9)
Bletilla striata 'Lips' (Lips Chinese Ground Orchid) This unusual Japanese selection has a purple-pink flower with 3 lips per flower instead of one...still quite rare. (Hardiness Zone 6-9)
Bletilla striata 'Murasaki Shikibu' (Murasaki Shikibu Chinese Ground Orchid) This unique selection of Bletilla striata has pale lavender flowers with a darker lip which appears bluish to the eye. In our experience, Bletilla striata 'Murasaki Shikibu' is not as vigorous as the typical species. (Hardiness Zone 6-9)
Bletilla striata 'Soryu' (Soryu Chinese Ground Orchid) Bletilla 'Soryu' is very similar to Bletilla 'Murasaki Shikibu' with blue-lavender flowers. (Hardiness Zone 6-9)
Bletilla szetschuanica and Bletilla yunnanensisare two species that are now theorized to be natural hybrids of Bletilla formosana and Bletilla ochracea, according to the Flora of China.
List of Bletilla Hybrids
Bletilla 'Brigantes' (Brigantes Chinese Ground Orchid) This 1994 Richard Evenden introduction is a seed grown cultivar from a cross between Bletilla striata x Bletilla ochracea. The plants have rose-purple petals and sepals, highlighted by a purple lip with yellow markings. (Hardiness Zone 7-9, guessing)
Bletilla 'Coritani' (Coritani Chinese Ground Orchid) This 1993 Richard Evenden hybrid is a cross of Bletilla formosana x ochracea. (Hardiness unknown)
Bletilla 'Kate' PP 19,878 (Kate Chinese Ground Orchid) Bletilla 'Kate' is a clonal selection of Bletilla 'Yokohama' (Bletilla striata x Bletilla formosana) from William Mathias of Wild Orchid Company. Mature clumps of Bletilla 'Kate' can produce 40" tall flower spikes with up to 35 flowers each. The light lavender flowers are highlighted by a yellow lip. Hardiness Zone 6 -9)
Bletilla 'Yokohama' (Yokohama Chinese Ground Orchid) This seed grown cultivar, first produced by N. Suzuki in 1956, is a hybrid of Bletilla striata and Bletilla formosana that produces 18" stalks of light lavender flowers. (Hardiness Zone 7-9)
Bletilla Penway Series The UK National Collection holder, Richard Evenden, created a series of hybrids, most of which are marketed under the Penway names (as an homage to the road that he lives on).
-- Bletilla 'Penway Dragon' (Penway Dragon Chinese Ground Orchid) A 1994 introduction, Bletilla formosana x szetschuanica, with lavender pink flowers and a white lip. (Hardiness unknown)
-- Bletilla 'Penway Imperial' (Penway Imperial Chinese Ground Orchid) A 2000 introduction, Bletilla striata x yunnanensis, color not known. (Hardiness unknown)
-- Bletilla 'Penway Paris' (Penway Paris Chinese Ground Orchid) A 1994 introduction, Bletilla striata x szetschuanica, with light lavender flowers and a purple lip. (Hardiness unknown)
-- Bletilla 'Penway Princess' (Penway Princess Chinese Ground Orchid) A 1994 introduction, Bletilla striata x szetschuanica, with light lavender flowers, a yellow lip, and red speckles. (Hardiness unknown)
-- Bletilla 'Penway Rainbow' (Penway Rainbow Chinese Ground Orchid) A 2000 introduction, Bletilla 'Yokohama' x ochracea, with cream flowers and a yellow lip flecked purple. (Hardiness unknown)
-- Bletilla 'Penway Rose' (Penway Rose Chinese Ground Orchid) A 2000 introduction, Bletilla ochracea x yunnanensis, with light lavender flowers and a yellow lip. (Hardiness unknown)
-- Bletilla 'Penway Starshine' (Penway Starshine Chinese Ground Orchid) A 2000 introduction, Bletilla 'Yokohama' x szetschuanica, with light lavender flowers, a yellow lip, and dark purple accents. (Hardiness unknown)
-- Bletilla 'Penway Sunset' (Penway Sunset Chinese Ground Orchid) A 1994 introduction, Bletilla szetschuanica x ochracea, with light cream flowers and a yellow lip with purple flecks. (Hardiness unknown)
Calanthe (Calanthe Orchids)
Calanthe is a large genus with over 150 species, although only 7 species are grown in temperate gardens. Calanthe are widely distributed from tropical Africa to tropical and subtropical Asia, the Pacific islands and Australia. Calanthe flowers encompass the colors of red, orange, brown, yellow, and cream. The genus name Calanthe is derived from the Greek word kalos (beautiful) and anthos (flower). The first recorded man-made orchid cross of any kind was made in this genus. John Dominiyi, the father of modern orchid breeding, crossed Calanthe masuca and Calanthe furcata to create Calanthe 'Dominiyi' in 1856.
Calanthes are one of the easiest hardy terrestrial orchid genera to grow. Calanthes are composed rosettes of large, flat, evergreen and semi-evergreen leaves and bloom in the early spring with a spectacular display of flower spikes. In the wild they grow in lightly shaded to densely shaded forests. I've seen them growing in Korea in the dense shade of Japanese hollies, where it was nearly too dark to see. In the garden, they can tolerant anything from dark shade to early morning sun. Although calanthes are fairly drought tolerant, they grow and flower much better in rich, evenly moist, organic soils.
List of Calanthe Species
Calanthe aristulifera (Mt. Kirishima Calanthe Orchid) One of the rarest of the Japanese endemic species, Calanthe aristulifera hails from the mountains of Japan's Kyushu Island. Calanthe aristulifera forms an 18" wide clump of pleated, evergreen leaves, topped in mid-spring with 15" tall flower spikes lined with small light pink flowers. (Hardiness Zone 7-9)
Calanthe discolor (Discolor Calanthe Orchid) The Japanese native Calanthe discolor emerges from the pseudobulb with 2-3 heavily pleated 6" long by 2" wide leaves. As the bulb offsets, the clumps can get quite wide. The foliage, which is evergreen to 15 degrees F, is topped in mid-spring with 10" stalks of tiny mahogany flowers with pure white lower lips...a very easy-to-grow addition to that special spot in the woodland garden. (Hardiness Zone 6b-9)
Calanthe discolor 'Eco Rose' (Eco Rose Discolor Calanthe Orchid) This Don Jacobs selection has flowers with rose colored petals and a pinkish white lip. (Hardiness Zone 6b-9)
Calanthe discolor 'Eco White' (Eco White Calanthe Orchid) Many years ago, we obtained this superb Asian orchid from Don Jacobs of Eco Gardens. Don purchased the plant in Japan back in the early 1980s. What thrilled us was that this hardy orchid has been the fastest multiplying of the Calanthe in our garden. Calanthe 'Eco White' is a selection of the Japanese native Calanthe discolor. In late spring, the pleated green leaves lay flat to form a nice background for the spikes of white lipped flowers backed with chartreuse green petals. (Hardiness Zone 6b-9)
Calanthe kawakamiense (Taiwan Calanthe Orchid) The evergreen, ground-hugging, olive-green foliage gives rise in early spring to 3' tall flower spikes of large, fragrant, bright yellow flowers. This is a stunning plant in flower, but unfortunately the winter hardiness leaves a bit to be desired. (Hardiness Zone 8b-10)
Calanthe nipponica (Golden Spiritual Calanthe Orchid) A rare, high-altitude (8000') Japanese species that hails from the mountains on Hokkaido and Kyushu as well as southeast Xizang, China. The 10" tall flower spike produces 4-5 pale yellow and green flowers. (Hardiness Zone 5-8)
Calanthe reflexa (Natsu-ebine Orchid)Unlike many of the other hardy calanthe, this one is a summer bloomer. The narrow-pleated, evergreen leaves lie outward, making a 15" wide rosette. In mid-to-late summer, the clumps are topped with lightly fragrant, two-toned, pink-and-white flowers (Hardiness Zone 7-9)
Calanthe sieboldii (Ki-ebine Hardy Calanthe Orchid) (syn. Calanthe striata) This hard-to-find Japanese native terrestrial orchid has been a superb performer and one of our favorite calanthes. The evergreen foliage (except below 10 degrees F) composes a vigorous 15" tall by 15" wide clump of deeply pleated leaves. In spring, the bloom stalks rise from the ground to reach 15". Along the scape are dozens of small pansy-like flowers of bright yellow. (Hardiness Zone 7-9, possibly colder)
Calanthe tricarinata (Hardy Monkey Calanthe Orchid) An early spring-flowering orchid, Calanthe tricarinata is topped with wonderful 15" tall spikes of stunning yellow flowers with reddish-brown lips. The foliage is evergreen in mild winters but may become deciduous when temperatures approach 10 degrees F. (Hardiness Zone 6-9)
Calanthe Hizen Hybrids (Hizen Calanthe Orchid)This series of hardy orchid hybrids from Japan (Calanthe discolor x Calanthe aristulifera) form basal rosettes of heavily pleated olive green leaves. The 8" flower spike emerges in early spring and contains up to a dozen flowers, each creamy-to-light pink with a darker pink/purple lip. (Hardiness Zone 7-9)
Calanthe sieboldii Takane Hybrids (Takane Hybrid Calanthe Orchid) These Asian hybrids of Calanthe sieboldii make a tropical-looking clump of 8" long by 2" wide pleated green leaves. In spring, the clumps are topped with 8" long stalks of brilliant yellow and orange flowers. (Hardiness Zone 7-9a)
Calanthe Kozu Spice Hybrids (Kozu Spice Hybrid Calanthe Orchid) Hybridized for flower shows in Japan, these hardy terrestrial orchids (Calanthe discolor x Calanthe izu-insularis) are now available in the US. These are perfect candidates for the woodland garden, the evergreen pleated leaves mature in the fall and remain during most winters. In spring, the 1' flower stalks emerge, then become clothed in flowers with a wonderful clove-like scent. The flower color may include bicolor combinations of white and red, yellow and red, pink and red, etc. (Hardiness Zone 7-9, possibly colder)
Spiranthes (Lady's Tresses)
The genus Spiranthes is commonly called Lady's Tresses, which refers to its braid-like spiral of small flowers. It is a genus of around 30 species that has a worldwide distribution in the northern hemisphere. The majority of species are native to North and Central America. The genus name is derived from the Greek "speira" (spiral) and "anthos" (flower). The spiral is often so tight it is hard to discern, but some individuals have beautiful, long, curving, spiral architecture. Only a handful of Spiranthes species are considered to be showy enough to grow in the garden. Spiranthes flower color is typically white but may be pale yellow or pink. Spiranthes produces 1' tall spikes than can have up to 50 tiny, tubular flowers arranged in a spiral. They are all fall bloomers with the exception of Spiranthes vernalis (Spring Lady's Tresses) and Spiranthes aestivus (Summer Lady's Tresses). The most commonly grown species are Spiranthes ochroleuca and the fragrant Spiranthes cernua. The species do not readily cross with each other because they have different chromosome numbers but there are a few naturally occurring site-specific hybrids.
Spiranthes prefer full sun in the North but they like protection from midday sun in the Southeast. In its native habitat, Spiranthes grows in moist soils,bogs, and swamps in meadows, fields, and forests. We have had good luck growing it in normal well-prepared garden soil with regular irrigation. Spiranthes spreads slowly via runners when it is happy.
Spiranthes cernua var. odorata (Nodding Ladies' Tresses) (syn. Spiranthes odorata) This native orchid is the southern form of Spiranthes cernua, ranging from Virginia south to Florida. The ground-hugging, dark-green rosettes spread slowly by underground rhizomes, creating a nice colony when growing in native habitats such as moist soils, bogs, or swamps. In mid-September, the insignificant rosettes produce incredible 1' tall spikes spiraled with small, white bell-shaped flowers, emitting a delightful fragrance often described as a cross between vanilla and jasmine. (Hardiness Zone 3-9)
Wintergreen Single-leaf Orchids
The single-leaf wintergreen orchids (aplectrum, cremastra and tipularia) each form a large single solitary leaf in the fall that persists through the winter and finally dies off just before the flowers arise in the spring or summer. This trait is common in the orchid family and occurs when summer temperatures or summer water availability are not conducive to summer survival.
Aplectrum hyemale (Adam-and-Eve Orchid)Scattered from Canada through North Carolina, and south into Georgia, grows one of the strangest plants that I remember as a kid.... the Adam-and-Eve orchid. This bizarre orchid produces a solitary, large, 8" tall green and white vertically striped leaf that remains up from fall until late spring. In spring, the 15" tall spike of tiny yellow to yellow-green flowers emerges... it's really dainty, so plant it near the path. Adam-and-Eve orchid grows best in moist shade, although summer drought during dormancy is not a problem. (Hardiness Zone 2-8)
Cremastra appendiculata (Handle Orchid) Native to China, Korea, Taiwan, India, Vietnam, Thailand, and Japan from 3000' - 6000' elevation, this rare and endangered, but fairly easy-to-grow late-spring-blooming orchid has stalks of peach-colored flowers in early summer. The large 1' long green leaf emerges in fall and persists all winter. (Hardiness Zone 6b-9)
Cremastra unguiculata (Handle Orchid) This Japanese native to Hokkaido, Honshu, and Shikoku is rarely seen in the cultivation. The 3-4" long green leaf, often purple spotted, grows in the winter and goes summer dormant. In summer, the lightly fragrant flowers composed of a white lip and tan petals dangle from the 10" tall flower stalk. (Hardiness Zone 6-8)
Cremastra variabilis (Variable Handle Orchid)Native from Russia south to Northern China and Japan, Cremastra variabilis grows in high altitude grassy openings in forests. The 8" flower spike that tops the leafless clump in early summer holds 10-20 1.5" flowers that are purple/pink and fragrant. The foliage emerges in fall and persists all winter. (Hardiness Zone 6-9)
Tipularia discolor (Cranefly Orchid) Most folks have never seen the dozen pale pink tiny flowers on a single 1' tall flower stalk in late summer after the leaves die back. What folks usually see instead is the 3" long olive green to dark purple leaf that emerges in fall and grows all winter. Tipularia discolor is widespread in dry woodlands from New York south to Texas. (Hardiness Zone 5-9)
Moisture Loving Hardy Orchids
Some orchids prefer moist habitats in the wild. Most species of calopogon and epipactis frequent wet, sunny swales, bogs, fens, streams, ponds, wet prairies, road ditches and the edges of marshy areas. Habenaria species like to live slightly up slope of calopogon but can still be considered moisture lovers. These plants require a constant supply of moisture, but do not necessarily like to sit in water for long periods.
Calopogon pallidus (Pale Grasspink Orchid)Calopogon pallidus is a common southeast US native orchid species that ranges from Virginia south to Louisiana, where it can be found in acidic pine savannahs and open meadows. The grass-like foliage serves as a foil in late spring to the spikes of fragrant 1" flowers (up to 16 per stalk) that vary from white to pale pink. Calopogon flowers are unique because the labellum, which on most orchids is located below the petals, is at the top of the flower and has ornamental yellow hairs. (Hardiness Zone 7-10)
Calopogon tuberosus (Grass Pink Orchid) This amazing, little, easy-to-grow orchid ranges from Minnesota south to Florida and is found in open boggy soils and meadows. Grass pink emerges in March (South) and July (North) with bunny-ear shaped leaves. Atop the leaves are stalks of up to 24 small, pink flowers that open progressively over a series of weeks. Grass pinks will need to reestablish well before attaining full height of nearly 3' tall. (Hardiness Zone 3-9)
Epipactis gigantea (Giant Stream Orchid) Native to the western US from Texas to British Columbia, it grows in moist locations and goes dormant at the first sign of drought. The 2-32 flowers on each spike are 1.5" wide and are pale yellow to yellow brown and are held on 3' tall spikes. Epipactis gigantea is a rhizomatous spreading species that tolerates sandy soils, clay soils and seasonal flooding. This species is easy to grow, provided it is kept dry in the winter. (Hardiness Zone 5-7)
Epipactis gigantea 'Serpentine Knight' (Serpentine Knight Giant Stream Orchid) This particularly fine selection with burgundy stems and leaves was discovered by California garden designer extraordinaire Roger Raiche. The clumps are topped with 18" tall spikes of small greenish-yellow flowers with burgundy stripes in spring. (Hardiness Zone 5-7)
Epipactis thunbergii (Persimmon Orchid) This Japanese terrestrial orchid grows along streams and in damp meadows in the wild. The clumps produce up to 20, 1.5" wide, orange-yellow flowers on 2' tall spikes. (Hardiness Zone 5-8)
Habenaria radiata (Egret Plant) Native to China and Japan, the white flower of this orchid has frilled petals and looks like an egret. It prefers a very well drained but moist soil such as sphagnum moss mixed with sand...difficult to grow. (Hardiness Zone 5-10)
Platanthera blephariglottis (White Fringed Orchid) This US native from Canada south to Florida and west to Texas can be found growing with Platanthera ciliaris. Both flower from mid-August to mid-September (NC) with panicles of white fringed flowers on 3' tall stalks. (Hardiness Zone 4-9)
Platanthera ciliaris (Yellow-fringed Orchid) This amazing native can be found from Canada south to Florida and west to Texas, where it grows in acidic, seasonally flooded soils. This amazing 3' tall specimen flowers in late summer with fabulous panicles of creamy orange fringed flowers (Hardiness Zone 4-9)
Rare Hardy Orchids for the Garden
Cymbidium goeringii (Noble Orchid) Cymbidiums are often grown as houseplants, but there is at least one species with good cold tolerance, Cymbidium goeringii. We have tried reportedly winter hardy cultivars of Cymbidium ensifolium and Cymbidium sinense with no luck so far. As a rule, cymbidiums are very easy to grow as long as they have good drainage. I recall first seeing Cymbidium goeringii in the wild in Korea and thinking that it looked just like a liriope. It has long been cultivated in both Korea and Japan, where it is native, as a highly prized potted specimen. We have found the Korean forms to make better garden plants than clones we have grown from Japan. The stiff, narrow green leaves make a small clump, topped in early spring (March in NC) with 10" spikes of miniature yellow-green cymbidium orchid flowers. (Hardiness Zone 7-9)
Goodyera pubescens (Rattlesnake Plantain Orchid) This East Coast native is found in acid woodlands, where it makes a 1' wide patch, spreading by short underground rhizomes. The small flat rosette is composed of blue-green leaves etched with silver veins, and the clumps are topped with short spikes of small white flowers in spring. There are three other US native species, Goodyera oblongifolia (western rattlesnake plantain), Goodyera repens (downy rattlesnake plantain), and Goodyera tesselata (lesser rattlesnake plantain). (Hardiness Zone 5-8, at least)
Some orchids such as pleione have species that are cold hardy but cannot tolerate winter moisture. In their native habitat, many of the 20 or so species grow on mountain slopes that provide perfect drainage. The best place to plant these is at the base of a tree which will keep the ground dry during the winter and thus ensure their survival. This technique also works for hardy cyclamen.
Pleione bulbocodioides (Peacock Orchid) Native to Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Shaanxi, Sichuan, Xizang, and Yunnan, China at elevations from 3000' - 10,000'. The 5" tall purple flowers with a yellow lip emerge in early spring alongside the short green leaves. (Hardiness Zone 7b-10)
Pleione yunnanensis (Yunnan Peacock Orchid)Native to the mountains of Yunnan, Sichuan, Guizhou, and Xizang, China from 3500-10,000' elevation, this has been the only species that we have had luck growing. The deciduous foliage reemerges in early spring alongside the short, but large lavender pink flowers. (Hardiness Zone 7b-9)
Been There, Killed That
We would be remiss if we did not mention that some hardy orchids just do not do well in the Southeast US. They cannot tolerate aspects of our tough climate such as our extreme summer heat, rain or humidity, our cool wet winters, or our periodic droughts. We at Plant Delights Nursery have trialed many orchids that just did not work out for us, no matter what we have tried. One genus in particular is dactylorhiza, which is native to cool parts of the world including the northern US states, northern Europe and the Himalayas. Some species are truly spectacular in flower, but so far we have not been able to keep them alive for very long. We have also failed with many species of liparis and orchis, although we continue to experiment.
We hope that after reading this essay you will be as excited about hardy orchids as we are. Some are easy to grow, others are more difficult, but all are worth including in your garden because they are marvelous plants. If you are new to hardy orchids, start slow. Try bletilla, calanthe, or Spiranthes first, and then move on to some of the more challenging orchids...good luck!
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