Selections for Growing Outdoors in Tropical and Temperate Regions

WHILE MOST OF US CULTIVATE OUR tropical orchids in some sort of protected environment, in many parts of the country there are various kinds of orchids that can be grown outdoors as garden plants. Your regional climate will dictate your options.

CYMBIDIUMS  Coastal California’s Mediterranean climate offers a number of possibilities. The moderate temperatures found from San Diego through the central coast to San Francisco are so well suited to cymbidiums that they are the leading orchid crop in California. They are popular garden plants in that area too. A number of gardeners who grow cymbidiums are such enthusiasts that they collect and grow the hybrids to the exclusion of all other orchid types, much as one might develop a rose or daylily collection.

Lauris Rose of Cal-Orchid in Santa Barbara, California, says that there are more than 100 acres (40 ha) of cymbidiums currently being grown in the state. 

“We grow those with strong color and look for different and unusual cultivars from seedling populations as well as new imports in order to keep our customers interested,” she says, adding, “But as the saying goes around here … anyone can grow a cymbidium, not everyone can grow one well.”

The types of cymbidium orchids that thrive in this region of the Pacific coast require some weeks of chilly, but not frigid, weather in order to flower. This is what makes these plants somewhat difficult for the average orchid hobbyist to grow but well suited for coastal California gardeners. Rose says that the plants will tolerate a temperature as low as 26 F (-3 C) although flowers and buds are damaged at 28 F (-2 C). She explains that the central part of the state has weather that is much hotter and drier in the summer and too cold in the winter for cymbidiums to be grown outside.

While our focus at Cal-Orchid, Inc., is primarily on terrestrial orchids, Rose told me about some epiphytic orchids they have been producing that bring a decided tropical atmosphere to the gardens in that Mediterranean climate.

She explained that orchid producers around Santa Barbara have been developing and promoting cymbidium companions for the gardeners who heretofore have opted for cymbidiums only. 

The showy species Laelia anceps and its hybrids are proving to be great plants for this purpose. Found in a variety of habitats in Mexico and Honduras, including the mountains, L. anceps seems right at home in their regional gardens. She states that orchid breeders, including Stewart Orchids, Santa Barbara Orchid Estates and Cal-Orchid, among others, have been actively crossing the numerous and variable forms of L. anceps with larger-flowered hybrids of Brassolaeliocattleya to produce new temperature-tolerant hybrids that grow well outdoors and typically flower in the winter there.

Laelia anceps varieties range considerably in color, but most are pink tones with a darker purple lip. Rose admits that the color selection of the California hybrids is heavy in the lavender shades but noted that the hybrid Sophrolaeliocattleya Coastal Sunrise (L. anceps × Slc. Helen Veliz) was a color breakthrough in this type of breeding.

“The great appeal here is that we can mount the plants to trees in the landscape,” she says.

Rose has a clump of one of these hybrids at her home that produced 44 flower spikes this year. It was in bloom for nearly three months.

Another good group of outdoor orchids for these coastal areas is species and hybrids of Zygopetalum. Black spotting on the leaves is problematic if the water quality is poor. Most of these have a spicy fragrance.

Dendrobium kingianum and its cousin Dendrobium speciosum are also becoming popular garden subjects there. Rose says they will survive fire (she knows from first-hand experience), heat, cold and hailstorms yet happily flower through the spring and summer. They are fragrant as well.

The popular reed-stem epidendrums  (such as Epidendrum radicans, its hybrids and many cousins), are of easy culture and are almost always in bloom in coastal California. Cal-Orchid has hybridized heavily in this group and has developed plants with brightly colored large flowers on rounded, full heads. They suffer badly if the temperature goes into the 30s and will show some bronzing on the leaves if temperatures linger in the 40s. A little protection during the coldest weather seems like a small price to pay for their colorful reward, and growers seem to enjoy sharing the keikis the plants produce with their neighbors and friends.

SUBTROPICAL CHOICES  Don Carpenter, of Boca Raton, Florida, enjoys growing terrestrial orchids in his subtropical garden in a climate where most orchid growers maintain their potted and mounted epiphytic orchids outdoors. “They are less likely to blow away in a hurricane,” he says.

Spathoglottis species and hybrids grow particularly well for him. Carpenter has a large variety with yellow, white, purple and even particolored flowers. He has selected for those plants that carry their flowers well above the foliage and are in flower almost all year.

While the Spathoglottis generally do best with a bit of protection from the sun, Carpenter’s plants lost their semishaded habitat thanks to hurricane Wilma. He says they have done fine thus far in the winter sun but do not fare well in strong wind.
Another orchid in Carpenter’s garden that grows in partial shade is Phaius tankervilleae. These plants do best in a damp area that offers plenty of moisture in the root zone. A well-grown plant of this Asian genus will soon grow into a clump that rewards the grower with many tall spikes of showy flowers, primarily in late winter or spring. The flower spikes open semisuccessively from the bottom, which extends their impact for weeks.

Carpenter is particularly enthusiastic about the recent Phaius hybrids that have been made with the genus Calanthe. Phaiocalanthe Kryptonite (Calanthe Rozel × Phaius tankervilleae) is a particular favorite of his because of its long-lasting colorful flowers.

For a sunnier spot, Carpenter grows the comparatively sturdy and undemanding terete vandas, another good garden orchid for South Florida. Terete is a botanical term that refers to the shape of the leaves, being cylindrical in cross-section as opposed to the v-shaped leaves of other vandas. Vanda (syn. Papilionanthe) Miss Joaquim (hookeriana × teres) is an early hybrid of this type.
Carpenter says terete vandas will grow in many types of soil and need to be trained on a short trellis or none at all. He observes that they do not seem to bloom well until they stop climbing and tells of watching them ascend tree trunks without a flower until they reach the top.

Reed-stem epidendrums and some examples of the genus Sobralia are also included in Carpenter’s garden. Sobralia is a New World genus of orchids that mostly range in height from 2 or 3 feet (60 to 90 cm) to perhaps 10 feet (3 m). Many of these shrubby plants have rather showy Cattleya-like flowers that last only a day or so but are produced successively, creating a longer floral display. Most do best with at least half a day of sun. Sobralia violacea is one that I have included in my own South Florida garden.
A recent addition to that garden is Arundina graminifolia, which has a habit and appearance that is somewhat similar to Sobralia. This one, popularly called the bamboo orchid, is native to Asia. I planted the 4- to 5-feet- (1.2- to 1.5-m-) tall reed-stemmed plants in November and they have been in constant bloom for several months through the winter. It is documented that they flower throughout the year so I am hoping for a long display. The blossoms on my plants are whitish or pale pink, with a purple lip that has a yellow throat. They resemble miniature semi-alba cattleyas.

TEMPERATE CHOICES  Gardeners in temperate climates have fewer options for real garden orchids than do those living in warmer areas. The easiest, most popular and best known is Bletilla striata, a hardy Asian orchid that is sometimes called hyacinth orchid after its light, sweet fragrance. Cold tolerance for this orchid goes to about 5 to 10 F (-15 to -12 C), perhaps a bit colder with winter protection. The spring flowers are usually pink to purplish, but white forms occur. They will tolerate sun but do best in lightly shaded woodland settings. I have seen this orchid for sale with other outdoor perennials at nurseries and garden centers in the southeastern United States. 

Beyond Bletilla, the options for the casual Northern gardener offer choices in color and size. Certainly there are those enthusiasts and hardy-orchid specialists who will cultivate the lady’s-slipper orchids (Cypripedium). Many of these have spectacular flowers, but some require shaded bog conditions to thrive, a situation the average gardener does not offer. Similar cultural requirements are necessary for many of the other hardy orchids. When making a purchase, be sure to choose seed-grown or rescued plants that are now available on the market. 

There are quite a few fascinating and botanically interesting species to be found within the hardy orchid genera. Most are not commonly available so you will need to contact specialist growers to acquire them.

If you do not have the correct climate to cultivate some of these types of orchids, remember that many of our potted tropical orchids seem to benefit from some weeks outdoors during the summer months. Orchids thus sent to summer camp often need to be protected from sunburn. They generally need filtered light or semishaded conditions and should be checked for pests before you return them indoors. Some of them may even reward you with flowers while camping in your garden.