Dendrobium is the second after Bulbophillum biggest genus of orchids. It contains about 1200 species. Dendrobium is an Asian and Australian genus, and also dwells on many Pacific Ocean islands.
Dendrobium orchids grow naturally in diverse ecosystems – from warm rainforests to cold Himalayan mounts and dry Australian deserts. They are either epiphytic (which is illustrated by a genera name – Dendrobium means “who dwells on trees”), lithophytic or occasionally terrestrial orchids. Given the fact that they live in so many different biomes, Dendrobium is one of the most diverse orchid genera.
This genus contains both the tiny species as Dendrobium cuthbertsonii, Dendrobium lindleyi and a rather gigantic Dendrobium speciosum. Dendrobium flowers are also diverse – from butterfly-shaped Dendrobium bigibbum, bull-head shaped Dendrobium taurinum to a rather alien-looking Dendrobium antennatum and Dendrobium spectabile, and there are both fragrant and odorless ones in this genus.
The colors of dendrobium flowers vary from pink, lavender, red, purple, white, orange, yellow, green and brown to very rare for orchids blue (Dendrobium victoriae-reginae). All Dendrobium species are sympodial orchids with pseudobulbs.
Dendrobiums’ pseudobulbs vary in their shape and size and they are also rather attractive. Dendrobium senile has pseudobulbs, covered with white hair (which is reflected in species name – Dendrobium senile means “Old man Dendrobium”), and Dendrobium cucumerina bears cucumber-shaped leaves.
Dendrobium orchid care
This is not a surprise that there are no general instructions about Dendrobium orchid care and maintenance, given the fact that this is one of the most diverse orchid genera which lives in so different biomes. That is why they are divided into different groups, according to their specific demands. They are divided into cold, intermediate and warm-growing types, and they can also be divided into ones who need a cold dry rest period, and ones who do not need it.
Cold Dendrobium orchids
Cold-growing species are Dendrobium wattii, Dendrobium wangliangii, Dendrobium vonroemeri, Dendrobium vexillarius, Dendrobium vannouhuysii, Dendrobium sutepense, Dendrobium sulphureum, Dendrobium subclausum, Dendrobium stellar, Dendrobium sinominutiflorum, Dendrobium sculptum, Dendrobium rupestre, Dendrobium putnamii, Dendrobium piranha, Dendrobium otaguroanum, Dendrobium cuthbertsonii. They cannot tolerate warmth for long periods of time and need to grow at cool (up to 30 F) all year round, as they are mostly mountain miniature to medium-sized species. The best way to grow them is mounting on slabs because at cool conditions roots are very prone to rotting. Mounting is the best way to keep roots of these Dendrobiums healthy.
The second group is intermediate growing Dendrobiums, such as Dendrobium kingianum, Dendrobium nobile, Dendrobium crassifolium, Dendrobium crassicaule, Dendrobium amethystoglossum, Dendrobium gnomus, Dendrobium harveyanum, Dendrobium loddigesii, Dendrobium longicornu. All of them prefer intermediate temperature, half to full sun and moderate watering. Some representatives of this group need cold and dry dormancy to develop flower buds. For instance, popular Dendrobium nobile, Dendrobium kingianum and Dendrobium loddigesii produce keikis instead of flowers if not provided with cool temperatures (down to 30 F), but they prefer intermediate temperatures when they are vegetating. Some of them (Dendrobium nobile) are deciduous, and leaf yellowing is a good sign to reduce watering, as plant preparing to dormancy. Most of them normally grow in pots or hanging baskets, depending of plant habitus – for instance Dendrobium nobile and Dendrobium kingianum could be grown in pots, as they grow upwards, but Dendrobium loddigesii or Dendrobium harveyanum better grow in hanging baskets or mounted, because they have hanging pseudobulbs, growing downwards. The orchids that vendors label as Dendrobium nobile for sale are actually complex hybrids, including Dendrobium nobile as a parent plant, and some of this complex hybrids do not actually require such cold and dry dormancy, as they have some warm-group Dendrobiums in their pedigree. Moreover, what shops have as Dendrobium kingianum for sale are hybrids too. Dendrobium Berry Oda is a famous example of Dendrobium kingianum-based ¶
And the third group is so called warm Dendrobiums – well known Dendrobium phalaenopsis, Dendrobium speciosum, Dendrobium spectabile, Dendrobium tangerinum, Dendrobium taurinum, Dendrobium transparens, Dendrobium truncatum, Dendrobium unicum need warm grow conditions. Some of them such as Dendrobium phalaenopsis and spectacular Dendrobium spectabile need year-round hot to warm temperatures, but deciduous Dendrobium unicum needs cold and dry rest in winter but warm temperatures at summer. Most warm species normally grow in pots, but Dendrobium unicum suits better to be mounted on a slab.
What is about Dendrobium orchids for sale in shops? Most often you can find three types of Dendrobium. First – Dendrobium nobile complex hybrids, they are deciduous orchids with winter rest period and they flower in spring. Second – Dendrobium phalaenopsis hybrids, which have no special dormancy and can bloom throughout the year without problems. And third – are Dendrobium kingianum hybrids such as mentioned Dendrobium Berry Oda, which require a cold dry period at winter to bloom. I should say that hybrids are much more easy to grow than species Dendrobiums, and within species, the warm group is easiest to grow.
Without a proper care, Dendrobiums are prone to diseases such as root rotting, black rot, Fusarium wilt, Anthracnose and the most severe diseases are bacterial rots and virus. They are caused by an improper care – overwatering, improper temperature – too cold or too warm, light deficient and contact with pathogens. So first you have to isolate infected plant to stop pathogen spreading, second – identify cause and then choose anti-pathogen agent (antibiotic if it is bacterial rot or fungicide for fungi) and then after applying these medications you should provide plant with proper care, because you should eliminate the cause – improper care, but not the symptoms.