Reprinted from the UCI Arboretum 'Arboretum Quarterly' Vol. 4 No. 2
The vast majority of the eulophias originate from the summer and year 'round rainfall areas in Southern Africa. These areas receive nearly all of the rainfall during the hot summer. A prelonged drought occurs during the cool winter months. Most of the eulophias, with the exception of a few saprophytic species, have well-developed subterranean stems or roots, commonly called pseudobulbs, which allow the plants to go dormant during the long dry winter season. When the temperatures begin to rise in the spring, these pseudobulbs sprout and the plant renews its active growth.
In cultivation, we try to mimic the conditions under which a plant grows in nature. Eulophias can be grown outdoors in those parts of southern California where the temperatures do not regularly drop below freezing. Many of the eulophias grow in forests or along forest margins, so its best to grow them in filtered sun. They need a lot of light to grow well, but they will burn if exposed to full summer sun.
At the UCI Arboretum, we grow most of our eulophias in a mix which consists of 1 part vermiculite; 1 part perlite; 1 part peat moss; 3 parts pumice and 3 parts oak leaf mold. This mix provides a loose, well-drained soil medium which simulates the conditions of the forest floor where many eulophias grow in nature. We begin watering in the spring after the eulophias sprout and begin active growth. About one month after initiating summer watering, it is time to start fertilizing. I have had good results fertilizing every other week, alternating between a water soluble 20-20-20 mix and a mix which is low in nitrogen and high in phosphorus and potassium such as 3-10-10. I find it necessary to spray occasionally for summer insect pests, especially for scale and thrip.
As temperatures begin to drop with the approach of winter, most of the eulophias will begin to go dormant; their foliage will start to turn yellow and eventually collapse. Stop watering as soon as you notice the plant going into dormancy and keep the plants completely dry during the entire winter season. It is necessary to shelter the dormant plants from the winter rains, otherwise they will rot. Do not resume watering until you notice the dormant plants beginning to sprout in the spring.
Eulophias are easy to propagate by division. Most eulophias produce chains of persistent backbulbs which are linked together by short subterranean stem connections. These dormant back bulbs can be removed from the parent plant by cutting the connecting stem between the bulbs. These backbulb cuttings are then potted separately, using the same mix described above, and should sprout in the spring when the plants resume active growth. Best results are achieved by taking divisions which consist of three attached backbulbs. Do the divisions in January and be very careful not to break off the fragile little eyes or growth buds which may have already begun to swell up and grow. Sometimes the divisions will rot, but this can be mitigated by dusting a little bit of fungicide on the wound where the back bulb section is separated from the parent plant. We use powdered root hormone because it contains a fungicide and is conveniently available at retail nurseries.
At the UCI Arboretum we cultivate about forty species of Eulophia. Of these, several are exceptionally showy and easy to grow. Eulophia streptopetala is one of my favorites. This is a medium-size plant which produces foliage about one foot tall and flower spikes which are one and a half to three feet. The flowers are about one inch wide with green and brown sepals and bright petals. The lip is colored yellow and purple. This plant produces backbulbs which are only half buried, like a Cymbidium. Another showy, but more rambunctious species is Eulophia speciosa. This plant produces thick one foot tall leaves and has a very short dormant period. The flowers are about one-and-a-half inches wide, colored bright yellow with purple stripes on the lip. This plant has a very long flowering period, beginning in the late spring and continuing for several months. The flowering stem continues to elongate as more blooms are produced, eventually reaching six feet or more. Eulophia speciosa is often found growing near the beach in South Africa and grows very well in pure sand.
E. parviflora is another beach dweller which grows in sand. It is a medium-to-small size plant with nine-inch-tall leaves and slightly taller flower stems. The flowers are very similar to E. streptopetala, but slightly smaller with brown color on the underside of the two yellow petals. It is a very dependable bloomer and produces lots of pseudobulbs.
One of the showiest of all the eulophias is E. cucullata. It produces two-to-three-foot-tall spikes which are loosely covered with very showy purplish-pink, one-and-a-half inch wide flowers. This plant is more difficult to grow than the others mentioned here, but the flowers are very nice and it's well worth the effort.
Eulophias are generally not available commercially. Most of the species we grow were collected in South Africa and Zimbabwe. The UCI Arboretum does occasionally offer various species for sale, especially at its annual Summer Bulb Sale on the first Saturday of August.