Growing warm Asian orchids

Growing Warm Asian Orchid Species 

In this article I will share our observations and cultural principles for the wonderful orchids native to warm lowland forests of Asia.

We have visited four areas in Asia on our expeditions, Sikkim, Arunachal Pradesh/Assam Sarawak and  Laos. 

(Pic 1 – Map of Asia)

We will start with a look at the warm growing orchids of the Himalayas before moving on to Laos and Sarawak.

The Himalayas rise abruptly from the Northern Plains of India, formed from the great rivers of the Ganges, Indus and Brahmaputra, and a visitor driving into the Sikkim from West Bengal, or into Arunachal Pradesh from Assam starts at around 100m above sea level and ascends first through semi-deciduous Sal Forest (the dominant tree species being Sal tree or Shorea robusta) into a more mixed forest with more evergreen trees. This forested band is virtually continuous for thousands of miles across North East India, includes a number of significant reserves, and provides a home for Tigers, Elephant and in the wet areas Rhino.  It is also home to some charismatic orchid species.

(Pic 2 – Asian elephant in lowland forest)

In our experience visiting this habitat is straightforward and rewarding with many orchids growing along main roads and more within the designated reserves.

Let’s start with a look at the orchids on the forests along the Brahmaputra in Assam.

Kaziranga National Park is well known as home to the World’s largest population of Indian One Horned Rhino. We have seen these wonderful animals both inside and outside the reserve and they are often accompanied by deer and wild pigs. (we guess that the smaller animals know that tigers are hiding in the long grass and the only protection is to stand next to Rhino)

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(pic 3 – Rhino in Kaziranga National Park)

Kaziranga and the forests around are also home to some great orchids. Papilionanthe teres is particularly abundant growing in full sun in the tops of tall trees. In more shaded spots we found Aerides odorata which is a species we do very well with

(Pic 5 – Phalaenopsis mannii in Nameri National Park)

The roads leading into Sikkim and Arunachal Pradesh also have a number of warm growing deciduous dendrobium species. The most abundant in Sikkim is Dendrobium aphyllum while in Arunachal Pradesh it is replaced by Dendrobium transparens. Other species include Dendrobium fimbriatum, Dendrobium crepidatum and a little higher and cooler the dramatic Dendrobium densiflo

( Pic 7 – Dendrobium densiflorum – Sikkim)

Vandaceous orchids are abundant in the lowland forests of Sikkim especially Vanda ampullacea which often grows alongside Dendrobium aphyllum, together with Vanda pumila and Aerides multiflora, Rhynchostylis retusa, Ludisia trichorrhiza and Acampe rigida.

(Pic 8 – Vanda ampullacea – Sikkim)

In Laos we have spent time exploring the hills near to the Mekong river and up onto the Bolaven Plateau at around 1000m. A great diversity of warm growing orchids included Vanda denisoniana, Dendrobium thyrsiflorum, Dendrobium chrysotoxum, Coelogyne trinervis and letiginosa, and the small growing Cleisostoma teretifolium amongst 

(Dendrobium chrysotoxum, Paksong)

The forests in Laos are mixed with evergreen and semi-deciduous trees and a similar seasonal weather pattern to the himalayan lowland forests with wet summers and a dry cooler winter though in total rainfall the Himalayas are wetter. Near the Mekong temperatures vary from a winter range around 17C-32 to a summer range of 23-35C with an annual 2m of rainfall and at 1000m temperatures are from 11-23C in winter to 17-28C in the summer with 4m of rainfall. In Sikkim’s warm lowland valleys, temperatures 300m above sea level vary from a 11C-23C winter range to a summer range of 23-32C with 3m of rainfall. It is clear from this data that our ‘warm forests’ in Laos and India are not that warm in the winter!

In comparison the climate of lowland tropical habitats near the equator such as in Sarawak are constantly warm without a winter difference. In Kuching, Sarawak, lowland temperatures are constant throughout the year and vary from a minimum of 23C to a maximum of 32C. This data indicates that a number of different ‘warm growing’ orchid houses are needed to reflect the impact of latitude and altitude. So what should a grower do?

In the UK I have visited a number of rainforest attractions that maintain a minimum temperature throughout the year of 23C reflecting the climate of lowland tropical habitats near the equator but we feel that this is far from ideal. Firstly we want to grow orchids that do experience a seasonal difference, secondly we find that the majority of our target orchids grow somewhere in the 300-1200m altitude range, and thirdly the heating cost (and environmental impact) of maintaining a greenhouse at 23C is a not something we want to pay for.

Our response at IOPO is to grow our warm orchid species indoors in our living room - a room we heat to 16C for us and our cat anyway. We have set up several Ikea display cabinets and added grow lights to supplement the daylight plants receive from the north facing window opposite their wall.

The plants sit in trays to manage watering and we water plants with a pump sprayer every couple of days. Plants include our stock plants such as Phalaenopsis species (see Phalaenopsis lueddemanniana flowering below)

Although we have found the Phalaenopsis of Sarawak grow a little warmer that in our living room they seem to thrive in our constant temperatures and the lights help to raise day time temperatures to above 20C

We found Phalaenopsis such as Phalaenopsis bellina (above) enjoy shady spots in the lowland forests of Sarawak and so extremely high daytime temperatures are definitely not required.

For many of our Himalayan warm growing species a winter of 17C is actually too high and so they have a ‘holiday’ elsewhere in the our greenhouses. (11C in the top of our cloud forest greenhouse). 

Alongside our large plants we grow a number of miniature Asian species. Most of these we grow mounted to show of the natural growth habit. As many lowland forests are much dryer than the misty mountain rainforests we can offer dryer conditions to some of our warm growing species.