Dendrobium is a diverse genus of orchids with different cultural needs. Many go through a growth phase and then a rest phase during the course of one year and must be given water and temperature to match these periods of growth and rest. Flowers can last one day to many weeks, depending on the type. Owing to the extreme diversity of the genus, culture is categorised according to the following main types:
Phalaenanthe
Evergreen for several years, with thin, tall pseudobulbs, terminal inflorescences, usually appearing in the autumn or twice a year. Species such as Dendrobium affine, Dendrobium bigibbum, and Dendobrium williamsianum. Grow warm year round; 16℃ nights; water and fertilise heavily when roots appear from new growth in spring; medium light; reduce water and fertiliser after growth finishes; they should flower in the autumn. These grow well with Phalaenopsis, except for the rest period.
Spatulata (antelope type)
Evergreen for several years. Most are large, vigorous plants with long-lasting flowers in summer to several times a year. Species such as Dendrobium antennatum, Dendrobium canaliculatum, Dendrobium discolor, Dendrobium gouldii, Dendrobium johannis, Dendrobium lineale , Dendrobium stratiotes, Dendrobium strebloceras and Dendrobium taurinum. Grow warm all year (16℃ nights, 24 – 35℃ days); no rest period; can be kept cooler in winter if dry; medium to high light.
Dendrobium
Most of the plants are pendulous, with leaves all along the canes that most often drop with onset of cooler, drier weather. One to five flowers per node are borne from the nodes of the leafless canes in midwinter through early spring.
Group 1
Species such as Den. chrysanthum, Den. friedricksianum, Den. nobile and Den.wardianum Growth period in summer; give warmth, water and fertilise heavily from when roots appear until top leaf appears on canes. Then give high light, little or no water, no fertiliser, cool nights (5–10℃). In other words, forget about them.
Group 2
Species such as Dendobrium anosmum, Dendobrium crassinode, Dendobrium falconeri, Dendobrium fimbriatum, Dendobrium findlayanum, Dendobrium heterocarpum, Dendobrium loddigesii, Dendobrium moniliforme, Dendobrium parishii, Dendobrium primulinum and Dendobrium transparens. Culture same as Group 1, but winter nights 13℃. Deciduous species need virtually no water in winter.
Group 3
Most are pseudobulbous plants with pendent inflorescences. Species such as Den. lindleyi, Den. chrysotoxum, Den. densiflorum, Den. farmeri and Den. thyrsiflorum. In summer give warmth (16–32℃), medium light, medium quantities of water and fertiliser. In winter keep cool (10℃ nights), medium light, just enough water to keep pseudobulbs from shrivelling, no fertiliser.
Latouria
Leaves at top of pseudobulbs are large and leathery, inflorescence erect, flowers commonly yellow-green. Species such as Dendobrium atroviolaceum, Dendobrium macrophyllum and Dendobrium spectabile. Culture is as for antelope types, but cooler and drier when resting in winter.
Formosae
Cane like pseudobulbs, with black hairs on leaf sheaths and pseudobulbs often apparent. Flowers usually white, up to 4 inches across, two to three together from near the end of the pseudobulb. Long lasting. Species such as Dendobrium bellatulum, Dendobrium dearii, Dendobrium draconis, Dendobrium formosum, Dendobrium infundibulum, Dendobrium lowii, Dendobrium lyonii, Dendobrium margaritaceum, Dendobrium sanderae and Dendobrium schuetzii. Intermediate to cool all year; 10–16℃ nights, maximum 30℃ days. Water and fertilise when growing; give a slight short rest (dry) when growth is completed. Keep barely moist until growth starts again.