Growing dendrobium orchids in Trinidad and Tobago

Sharon Laurent

The plant family Orchidaceae which is the largest family of flowering plants with more than 22,000 species has many sub groups (899) called genera, (one is called a genus more are called genera) the second largest of these is the dendrobium genus.

Within each genus the plants are then divided into species. A species has unique characteristics in growth habit and flower form.

One species can be hybridised with other species from the same genus.

There are 1,523 recognised dendrobium species and thousands of hybrids.

Dendrobiums are found in nature from Asia and Australia and the islands occurring between and around this area. They occur from Japan, Taiwan and China in the north; India, the countries of the Malay peninsula, the Philippines, right down the island chain to Australia; from the foothills of the Himalayas to lowlands of the islands. Temperatures in the area range from 15 degrees to 37 degrees C.

Why does this matter to the hobby grower in Trinidad and Tobago who wants to grow dendrobiums? Recognising the usual wet and dry seasons, (even though this dry season is definitely not normal), the range of temperatures is usually from 20°C being the lowest at the coldest time of year to 35°C highs and very high humidities at some times of year will help you to select species and their hybrids that will grow and bloom easily.

The species can be divided into six main groups based on taxonomy and cultural requirements.

Group 1 – the Nobile or dendrobium group

Sub group 1. These species originate in Japan and bloom on upright canes, they require very cool nights to initiate flowers, 15°C or so. They are difficult to bloom satisfactorily in TT.

Sub group 2. These species originate in foothills of the Himalayas and Thailand, they have pendant canes and are deciduous (lose their leaves) and usually bloom in March. Some species that do well are anosmum, aphyllum and hybrids, they range in colour from white to deep purple. They enjoy lots of water and fertiliser followed by a dry spell from Christmas. They can grow on trees or in baskets in a light shaded area. Some of these species have been in TT so long some people think they are native species. Not all species in this group will flower in TT as some originate too high in the Himalayan foothills and require very cool nights to flower.

Goup 2 Phalananthe or phalaenopsis type

These species and hybrids look like small phalaenopsis orchids but with much smaller leaves. They flower well in TT giving long sprays of purple to white flowers. It is important to let these plants dry out between watering and not to over pot. They prefer light shade to full sun. Since they don’t like to be constantly wet it may help if you can grow them under some cover during the rainy season.

Group 3 Spathulata or horn-type dendrobiums

These dendrobiums have twisted petals and sepals and multi-coloured lips. They originate in the hot tropics and can grow in full sun and do not require any rest periods. The only drawback may be that they become very large plants.

Hybrids between phalaenopsis type dendrobium species and horn-type species are called intermediates and combine the best of both groups, they are usually smaller growing, come in a full range of colours and are easy to grow in TT.

Another time we will write more about the other groups of dendrobiums which will grow well in TT. One is dendrobium lindleyi from the Callista group.

Happy growing and blooming these gorgeous orchids!

For further information contact the Eastern horticultural Club at 357-5033, or 720-2698 or easternhorticultural@hotmail.com

The Club meets on the first Saturday of every month (except public holidays) at 3 pm at Morton Hall, Aramalaya Presbyterian Church, Cochrane St, Tunapuna. However, due to the covid19 pandemic meetings have been suspended until further notice.