Dendrobium harveyanum has distinctive golden-yellow flowers with long filaments edging the petals, while the round lip is fringed and densely pubescent (covered with fine hairs). The usually erect, spindle-shaped growths are 4- to 12-inches (10–30 cm) tall and have from two to nine leaves toward the top. The loosely pendent inflorescence is about 6 inches (15 cm) long, and comes from the top of the older, often leafless growths, and carries up to nine 2-inch- (5-cm-) wide flowers. Although the individual flowers are not long-lasting, perhaps 10 to 14 days, the quick-forming spikes will continue to emerge over a period of several weeks, which extends the floral display for up to six weeks. This species has a reputation for being difficult to grow. However, with a little understanding of the needs of this plant from a monsoon climate, the difficulties are easily overcome.
NATIVE HABITAT Found in Myanmar (Burma), Thailand, Vietnam and Yunnan Province of southern China, Den. harveyanum (den-DROE-be-um har-vee-AH-num) is considered an uncommon species in nature and habitat information is scarce because there are few published records of collections. In Yunnan, it blooms in March and April and occurs at elevations from 3,600 to 5,600 feet (1,100 to 1,700 m) where it grows as an epiphyte on tree trunks and large branches. This species was originally discovered in Myanmar and introduced into cultivation by the Liverpool Horti-cultural Company. It is named in honor of Enoch Harvey of Aigburth near Liverpool who, in 1883, was the first to flower it in Europe.
Dendrobium harveyanum comes from a classic monsoon climate with heavy rainfall and the accompanying cloudy skies in spring and summer, which are then followed in autumn and winter by no rainfall, bright light with cool nights and warm days. By winter’s end, the humidity is low, and most likely the plants receive little moisture, even from early morning dew.
WINTER REST I grew the plant shown at right poorly for many years, during which time I provided even moisture year round. It was a small, struggling specimen with few roots and almost no flowers. With nothing to lose, several years ago I decided to adopt a grow-or-die attitude and began giving it a prolonged dry rest in winter. It was as if I had a different plant: strong growths, lots of active roots and flower spikes every year.
POTTING I grow Den. harveyanum in a fine-grade epiphytic bark mix in a wood basket, but a pot would also serve if it is relatively small: This species and its relatives are notoriously intolerant of being over-potted. My mix consists of 6 parts washed and sifted fine fir bark, 4 parts medium perlite, 2 parts chopped tree fern (fibers approximately ¾ to 1½ inches [1.9 to 3.8 cm] long), and 1 part ¼ inch (.6 cm) charcoal, but any good epiphytic mix would do. Dendrobium harveyanum can be grown mounted on cork or tree fern if it is watered heavily and often during the growing season and is provided with adequate humidity.
When in active growth during the spring and summer, this plant receives moderately bright light with a balanced fertilizer at half strength for two out of three waterings. Daytime temperatures are in the 75 to 80 F (24 to 27 C) range and nighttime temperatures drop to 55 F (13 C). As autumn comes and the growths mature, fertilizer is discontinued and the frequency of watering is reduced, so the plant is quite dry between waterings. In late October or November, the plant is moved to a bright location in the greenhouse, where it receives no water. The daytime temperatures at this time of year are usually between 55 and 65 F (13 and 18 C), but will rise to 80 F (27 C) on sunny days. The night temperature is usually about 50 F (10 C), but the plant has experienced a few nights of 38 F (3 C) with no ill effects. I do not usually start watering the plant regularly again until the spikes have developed in the spring. I was once told an easy way to remember the dry winter rest period: withhold water from Halloween until Valentine’s Day (October 31st and February 14th).
References
Baker, Margaret L. and Charles O. 1996. Orchid Species Culture: Dendrobium. Timber Press, Portland. http://www.orchidculture.com
Banks, David. 1999. Tropical Orchids of Southeast Asia. Periplus Editions, Ltd., Hong Kong.
Chen, Singchi and Zhanhuo, Tsi. 1999. Native Orchids of China in Colour. Science Press, Beijing.
by Marni Turkel / Originally Published in Orchids Magazine
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