Green Culture Singapore
Feature Article for October 2005
Text & Pictures - Tan Boon Kiat
Online on 4 October 2005


Above: The popular Dendrobium orchid.

INTRODUCTION

Most of us living in the tropics will be familiar with the Dendrobium orchid. It is commonly sold as cut flowers in markets, florists and supermarkets. It is also a favourite among Singaporeans who purchase the orchid during the festive season like Chinese New Year to beautify their homes and usher in the God of Prosperity, hoping they will strike more Totos or 4Ds the coming year. The flowers are long-lasting and can provide weeks of joy, beauty and colour when the orchid is well-taken care of.


The Dendrobium is usually a beginner orchid and is often used as a benchmark against other orchids for culture in Singapore. I was given a miniature dendrobium orchid when I was in Primary Four. Like balsams, they were among the first plants that we grew during our younger days. They are very tolerant of a wide range of conditions, which make them good house plants in highrise apartments of Singapore. As the genus Dendrobium is a huge family comprising thousands of species and countless hybrids, I have used the locally available purple Dendrobium hybrid as a reference for our discussion here.


LIGHT


To grow them successfully, you have to ensure that your growing area has at least 2 hours of sun or you will find them difficult to grow or not growing at all. Of course if your area can get 5 hours of sun, that is even better. Sun is a deciding factor to grow these beautiful orchids successfully. No SUN no GROWTH. Once the light requirement is fulfilled, other factors like water, medium, fertiliser will be secondary and that is why I have devoted a good 50% of this article on light.


Dendrobium needs sun to develop long and sturdy stems or pseudo-bulbs before it is strong enough to produce flowers. The fatter the pseudo-bulbs, the better will be the blooms. When it is under sufficient light, it will grow rather slowly, taking about 2 months to reach maturity before it will bloom for you. Thus you need to be rather patient as an orchid grower as most orchids including Dendrobium are no exceptions. However, the flowers are very lasting and it is very rewarding when they bloom. When there is not enough light, the pseudobulbs will become dark green, thin and elongated. Pseudobulbs of this nature are unlikely to flower for you and might even harbour pests like red spider mites in the long run.

Most Dendrobium require about 75% sun to grow well. In most nurseries, this can be achieved by erecting a layer of black shading cloth over them as it is designed to allow only 75% of sunlight to pass through. It would be difficult to achieve this feat in HDB flats as erecting a cloth over our orchids will also inhibit air movement which is crucial to all plants including orchids. This is not much of an issue as most corridors or balconies of HDB flats are blocked by adjacent buildings, window grills or pillars during certain time of the day thereby giving protection to the plant.



How to achieve maximum light?


Above: The rim of its pot should be in line with the ledge of your balcony and
do not place the pot on the ledge to prevent the pot from toppling over.

You have to erect a plant stand for your Dendrobium orchids. As long as you can elevate the orchid such that the rim of its pot is in line with the ledge of your balcony or corridor, the orchid is getting sufficient light. It is important that light must reach the base of the pseudo-bulbs as this is the area where new growths are produced. In addition, I find that the roots of the orchid like to be exposed to sun. Somehow the sun will help to keep the roots dry, preventing rots from setting in. A good healthy root system is the basis in the fundamental health of all orchids.



Above: Dendrobium roots seem to like the sun alot!


I have seen growers putting their orchids on the ground. This is bad for the orchids in the long run. Orchids are epiphytic, meaning their roots adhere to tree branches for support to access air, light and rain. It is important for the roots to have a chance to dry out before it is wet again or rots will set in. If you notice some of the orchids that are placed on the ground, water will collect at the bottom of the pot and the roots will remain wet for days and sometimes weeks. Soon, the roots will rot and the orchid will die. If erecting of plant stands might be too cumbersome for some of you, you can hang them or tie them to some pipeline. An ingenious method is to erect a wire mesh and hook all your orchids to it.


Too much sun


Some brown leaf tips or yellowing of the leaves are inevitable as we are growing them in flats and not outdoors. However, those of you who are blessed with direct sun either in the morning or afternoon need not fret. Dendrobium are very forgiving and that is why I would like to introduce this orchid to you. They are superb orchids for high rise apartments and are very tolerant in a wide range of lighting conditions. Too much is better than too little.


Above: Brown spots and yellow leaves in Dendrobium.


However, if you find the sun is still too strong, you can try erecting a shade cloth over your Dendrobium by using bamboo sticks to push the cloth forward to allow air circulation. This can be done quite easily as my balcony has window grilles which can help to support the shading cloth. This feat can be tricky along common corridors and you may need to build a simple orchid trellis to anchor the shading cloth. You will need to water more often. Maybe twice a day. With the cloudy erratic weather we have recently, sunlight is getting scarce now especially in HDB flats.


The antelope Dendrobium or the horned Dendrobium fall under the full sun category. They need about 6 or more hours of sun daily. These orchids can grow up to 2 metres high and bear flowers with curly petals that look like some aliens landing on earth. The flowers are very lasting and can last for months. They are superb orchids in very sunny areas. My dream orchids too.


How to know your orchid is getting enough light?


As long as you have sun falling on the leaves, pseudo-bulbs and roots at different or same time of the day for at least 2 hours, then your orchid is getting enough light. In addition, you should also note the following:


(a) New growth are larger or about the same size as the previous growth.

(b) Leaf should be medium green though some hybrids may have a darker shade of green. The best is to compare the colour with the previous growth.


What happens when the sun changes direction?


Usually, the sun will change its direction approximately every half of the year or less depending on your direction. During this period, you will need to water or fertilise less since growth will be somewhat stunted. A fact that all high rise growers have to bear in mind.


Some Tips

(1) If your conditions are very different from what I have described and yet your orchid still blooms beautifully for you, don't change its position.

(2) Visit your neighbours to see how they grow their orchids. It is likely that you can grow them too.

(3) It always pays to purchase orchids from nurseries to know the amount of light that they are subjected to by the growers. If your area has full sun, go to the part of the nursery where orchids are grown without any cover and vice versa.


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