Growing Cool Asian Orchid Species 

Isle of Portland Orchids regulars will know that our aim when growing orchid species in cultivation is to understand and replicate the natural habitats. In this article we will share our experience of exploring the cool mountain monsoon forests of Sikkim and Arunachal Pradesh and explain the way that we grow orchids from this remarkable habitat.

From 1500m to around 2500m Sikkim has a band of diverse evergreen forest and here the wet season is really wet and the dry season is far from dry. During our visits to Sikkim in the dry season months October and March we have found that each morning the forests are dripping with dew and rain showers are not uncommon. We find that the temperatures at these times are around 10C at night and mid teens during the day. Coldest temperatures in January are a few degrees above freezing and frosts when they do occur have little penetration into forests.

To replicate these conditions our Himalayan Greenhouse has a minimum of 7C and vents that open at 17ºC The majority of the species we grow that are native to these cool Himalayan forests at Cymbidiums, Coelogynes Pleiones and Dendrobiums, so let us look at each in turn.

Cymbidiums were my first love as an orchid growing teenager and I still get a real thrill from a well flowered species.We have seen a number of cool growing Cymbidium species growing in Sikkim and these are well suited to our growing conditions on Portland.

The first group of Cymbidiums is the large growing cool species such as Cym. hookerianum, Cym. tracyanum, Cym. mastersii and Cym. erythraeum. These are all species of cool wet evergreen forests where they grow as epiphytes on the upper trunk and main branches of large trees and compete with ferns and other orchid species.

The photos above show Cymbidium hookerianum in flower in our greenhouse in February. We have found that all these Cymbidium species really enjoy the cool temperatures of our greenhouse and we find a minimum of 7C and masses of fresh air result in optimum growth and flower production.

Cymbidium devonianum occupies a different microhabitat and we found it growing in heavy shade low down on evergreen trees growing in detritus. This explains the broad soft leaves of the species that are clearly evolved to make the most of the low light levels. Growing the species shaded and wet avoids the brown tips to the leaves we used to suffer when growing Cym. devonianum amongst the other cymbidiums.

The lovely terrestrial Cymbidium insigne is found further along the Himalayas in Vietnam and Laos but grows very happily alongside our Sikkim species.

Moving on to Coelogyne, we have found lots of lovely species growing in similar habitats (often the same trees) as the cymbidiums. These species include C. cristata, C. nitida, C. fimbriata and C. strica , species we have all seen in the Himalayas.

These species are all abundant in suitable habitat above 1500m. C. nitida is particularly abundant around Gangtok and flourishes on mossy trunks and branches amongst its close relatives C. occulata and C. corymbosa. We have found that C. cristata has two favoured microhabitats, mossy trunks in wet forest and as a terrestrial on rock faces close to dripping mossy water run offs from the hillsides above. C. stricta can be found amongst C.cristata but we have also seen it growing in more exposed positions especially in Arunachal Pradesh where it grows high in tall trees and so gets exposed to bright light and a little less moisture than the other coelogynes described.

A clear indication from these habitat observations is the need for year round moisture for these species. Even though the dry season may have reduced rainfall the coelogynes will all have damp roots on the mossy trees or rocks and so we water our coelogynes throughout the year. The only dry period we give is when flowering as water spray quickly damages these lovely flowers.  

Amongst the Coelogynes we have also found the himalayan pleione species, Pleione maculata and Pleione preacox. Both species grow in thick moss on trunks and lower branches and we grow the lovely natural hybrid between the two species, Pleione x lagenaria in pure moss to replicate this microhabitat.

There are of course a host of other species that share these habitats and we grow a number of these including Epigenium species, Bulbophyllum species and Pholidota species. We are massive fans of these rewarding and relatively straight forward species. Perhaps in the UK we have forgotten the art of growing cool orchid species and it is time for a revival of the cool greenhouse.