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  Tucson Cactus and Succulent Society

Growing Succulents in the Desert Column

(List of Growing Succulents in the Desert columns)

Eulophia petersii: A Desert Orchid by Mark Dimmitt

(This article may only be reprinted with the author's permission.)

I was going to subtitle this article “A Succulent Orchid”, but that doesn’t say much. Of the 25,000 species of Orchidaceae worldwide, many thousands of them are succulent. But this is one of a relative few that grow in desert climates under the same culture as cacti or euphorbias. Dave Grigsby of Grigsby Cactus Gardens used to say, “Grow it like an aloe”. That’s pretty good advice, except that unlike most aloes, this orchid should be watered in summer and rested in winter.

Eulophia petersii is one of the most desert-adapted orchids. It grows in arid habitats from Namibia all the way to the southern Arabian Peninsula. An extreme succulent, it stores water in its large pseudobulbs, thick rigid leaves, and an ample system of fleshy roots. In spring 3- to 6-foot tall racemes bear hundreds of 1-inch brownish flowers with twisted petals. This species was introduced to succulent nurseries in the early 1990s, when it was rare and expensive, selling for $45 per bulb. It is now fairly easy to find.

Culture

Eulophia petersii will grow best in a deep pot that accommodates the big root system. Use a coarse, well-drained succulent mix. During the summer growing season, they can take quite a bit of water, but it’s best to water only when the medium dries out, about every two weeks. They can go months without water, especially during the cool season. It is tolerant of temperatures from well over 100 F to freezing. All-day sun is a bit too much in summer; the plant will look much better in very light shade. To ensure flowering, give the plant a cool, dry winter rest. While it can tolerate down to freezing or even a few degrees below under a cover, it tends not to flower after a cold winter outdoors or in an unheated enclosure. I keep my plants in a cool greenhouse with night temperatures about 45-50 F. Watering during winter also seems to inhibit flowering. I don’t water my plants at all from November until March. Plants are vigorous and will grow into large clumps that bear a dozen or more inflorescences. Repot or divide as needed; the best time is in late spring after flowering and when new growths are several inches tall. Single-bulb divisions will establish well, but three-bulb divisions will make normal-sized new growth and usually flower the very next year. Note: Verdins and goldfinches are fond of eating the flowers. If you have many of these birds, you may want to protect the plant when it’s flowering.

Other species

The genus Eulophia has about 300 species, many of which are xerophytic succulents with beautiful flowers. Most, unfortunately, are very difficult to find. Eulophia speciosa has fleshy strap-shaped leaves from underground bulbs and 2-foot tall spikes of bright yellow flowers that look like flying birds. E. orthoplectra is similar in size and shape, but its flowers are purple on the front and yellow on the back. E. keitii and E. leachii have non-succulent and succulent leaves, respectively, atop above-ground bulbs, and 1-foot spikes of small green flowers. Other species such as E. guineensis are herbaceous, bulbous perennials that grow in wet habitats, but also perform well outdoors in Tucson if kept well watered during the growing season.


List of Growing Succulents in the Desert columns