6 Key Success Factors to Growing Orchids in the Tropics

It is said that gardening in the tropics is easier than in any other part of other world because everything grows so fast and lush, and even those without a green thumb can succeed. But many tropical gardeners lament that they can’t grow orchids – or at least can’t get them to flower.

Actually, orchids are amongst the easiest of all plants to grow in the tropics – provided you know what the key factors are to growing them successfully. If you don’t get one of those factors right or neglect it completely because you didn’t know about it, then your chances of getting your orchids to flower and stay healthy plummets to almost zero because every factor is as important as the others.

Some of these factors will be obvious to experienced gardeners, whilst one or two may not. For newbies to tropical gardening, they may be more in the category of eye openers, but the implementation of these practices is just as easy whether you are a novice or an expert. There’s nothing particularly difficult about any of them.

So, let’s take a look at what these key success factors are and run through them in no particular order because everyone of these factors is an essential growing practice that must be incorporated into your orchid care regime.

We’ll focus on epiphytic orchids in this article, because those are the ones that most tropical gardeners have growing in their gardens – either in hanging pots with no potting media, in open clay pots with charcoal and/or coconut husk as the potting media or attached directly to trees or trellis structures. Ground orchids have similar requirements but there are only a few species of those usually grown in tropical gardens.

1. Provide Good Ventilation

Let’s start with the factor that’s most often overlooked, even by experienced gardeners, and that’s the need for good ventilation. Orchids need free-flowing air which is why you’ll often see fans in shadehouses where they are being grown in nurseries. That doesn’t mean blasting them with fans – it just means ensuring that there is good air flow.

The reason fans are used in shadehouses is that the shadecloth blocks the breezes, but when your orchids are in the open garden, the natural air flow around them will be quite sufficient. What you need to avoid is putting them on solid walls where the breeze will be blocked or in a part of the garden where the air is still because of adjacent structures.

2. Know the Light Requirements

Tropical orchids grow in all types of light from full sun to full shade but with the majority requiring a level of partial shade between those two extremes. There are over 100,000 orchid species and hybrids that can be grown in the tropics, so it’s not possible in an article like this to list the light requirements of every orchid species (you’d need an encyclopaedic sized book to do that!). What gardeners have to do is to find out from the nursery where they buy young plants what the specific light requirements of the orchid are so that an appropriate place can be found for the orchid in the garden.

If an orchid is gifted to you or is bought from a retailer who can’t tell you the light requirements, then you will need to determine that information through online research. Of course, you’ll need to know the name of the species or hybrid to do that. If you don’t have that, then you will have to determine its light requirements through trial and error.

In those circumstances, it’s usually best to start off by placing the orchid in a semi-shaded position. If the leaves start to show any sign of burning (brown scorch marks) then it needs to be moved to a shadier position. On the other hand, if the orchid doesn’t look like it’s making much progress and producing new leaves, then it probably needs more light.

For orchids that require half shade, the best growing conditions are provided under the dappled shade of a large tree. But it you are growing them in an area of the garden where you only have the choice of having them in the sun in the morning or the afternoon, then morning sun is always better because it’s generally not as intense as the afternoon sun.

3. Know the Water Requirements

Watering orchids is not as tricky as watering normal pot plants because the potting media is much more open and free draining, or in the case of many epiphytic orchids there is no potting media at all. The main requirement is simply not to let the roots dry out for too long. During the rainy season, you’ll only need to water on days when it doesn’t rain, and in the dry season an early morning watering should be sufficient.

Try to avoid evening watering because if the roots are too wet overnight, that may make the plant more susceptible to fungal infection. For potted orchids, make sure the whole pot gets a good soaking so that you don’t end up with dry areas in bunches of matted roots in the middle of the pot.

Some species of orchids (as is also the case with some species of ferns) don’t like chlorinated water so it’s always better to water orchids with rainwater if you have a rainwater tank. If you don’t, then store tap water in open drums in the sun for a couple of days, and the chlorine will dissipate making the water ideal for watering orchids and ferns.

You can place a sheet of flyscreen over the top of the open drum to prevent mosquitoes breeding in the still water, or alternatively regularly check the drum to make sure there are no mosquito larvae in the water.

4. Know the Temperature Requirements

As well as specific light requirements, every species of orchid has specific temperature requirements. That’s why you will see completely different species of orchids being sold in tropical highland areas (where the days and nights are cooler) compared to tropical lowland areas.

So a good rule of thumb is only to buy orchids from nurseries in the same climatic zone as to where you are living. Often people living in tropical lowlands will go to the highlands and see some beautiful orchids that they’ve not seen before, and buy them, only to be disappointed when they never flower again in the area where they are living.

Generally speaking, you can rely on the nurseries and garden shops in your locale to only be selling orchids that are suitable for the temperatures in your region – but with one exception. Many places sell pots of flowering Phalaenopsis orchids that are grown under cooler conditions (either in special cool houses or imported from a country with a cooler climate).

Phalaenopsis orchids are popular as they flower for many months and cope well with an indoor environment – but they are sold tropics for their long-lasting decorative properties once they have achieved flowering, not as a plant that you can keep growing. They are not a species of orchid that you can transfer to the garden and expect to flower again unless with are living in a tropical highland region with cool nights.

5. Fertilise Regularly

Whilst all the factors listed in this article are as important as each other, the one that you cannot afford to get wrong is the need for regular feeding. Orchids require fertilising much more frequently than most other tropical plants, and it is this factor where most beginners fall down.

Orchids must be fertilised every two weeks during the growing season to achieve optimal growth and flowering. Keen gardeners and specialist growers will fertilise every week at half strength. A mix of chemical and organic fertilisers is important in order to provide the plants with all the trace elements that they need.

For the chemical (inorganic) fertilisers it’s best to use the powder fertilisers that have been formulated specifically for orchids. An NPK fertiliser of 10-10-10 or 15-15-15 is fine for general use but be sure to follow the dilution instructions closely to avoid burning the plant. In the months before flowering (most orchids flower at specific times of the year) you can switch to 10-20-10 or 15-30-15 to help promote flowering.

Only liquid fertilisers should be used. Never use the granular fertilisers that are sold for general garden use. It’s best to alternate the chemical fertilisers with organic fertilisers like fish emulsion or seaweed extract to ensure that the plants receive the minor and trace elements. Another way to do this is to apply a monthly trace element mix, but the inclusion of organic fertilisers is still important for the overall health of the plant.

6. Grow Outdoors

The inclusion of this as a success factor might sound silly to more experienced gardeners but many newbies take orchids home from the nursery and treat them as indoor plants and wonder why they never flower again. Simply put, orchids will never grow well indoors because they won’t have the free airflow that they require, and it is difficult to provide them with the correct light requirements.

Yes, in temperate climates some people do grow tropical orchids indoors, but they do that in expensive vivariums or window glasshouses where they can control light, temperature, and humidity. In the tropics you don’t need all that fancy equipment because you have all the requirements for growing orchids in your garden outdoors.

You can certainly bring orchids indoors for display purposes when they are in flower, but as soon as they start to look weary, you need to put them back outside. They will stay in flower for longer outside. Many orchid growers who like to have flowering orchids inside the home will rotate their plants after a few days. For example, having the plant indoors for only a few days at a time and then putting it back outside to recover is another way of prolonging the flowering.

Balconies are a sort of halfway house between outdoors and indoors. Many species of tropical orchids do well on balconies, but you need to give special attention to ventilation and light requirements. Some won’t do well on balconies at all, especially if the balcony gets very hot in the afternoon. You can experiment to see which species do well and which ones don’t.

Other Important Factors

Whilst the six factors listed above are the keys to successful orchid growing, some gardeners might say that the correct growing media is a seventh key success factor. That’s true of course, but we’re assuming that orchids purchased for growing in the garden are sold in the growing media that is best for their ongoing development.

If you get into propagating orchids, there is a need to know more about the best growing media, but that’s well beyond the scope of this article. The most important thing for beginner orchid growers to know is not to change the type of growing media. We’ve heard stories of people buying bare rooted Vandas and then potting them up into a conventional potting mix. Of course, their Vandas will soon die.

If you buy a Vanda that’s hanging from a wire hook with no growing media, then that’s the way they should be grown in the garden. If the orchid is growing in a plastic mesh pot without any growing media, then don’t try adding materials to the pot. If it’s in a pot with charcoal and broken terracotta pieces, and you have to repot at some stage, then use the same type of growing media.

If an epiphytic orchid is bare rooted, or even potted into a loose charcoal mix, you can take it out of the container and tie it to a tree or the trunk of a palm (keeping in mind its light requirements) and it will soon attach itself to the host tree and not require any other form of support.

However, make sure what you use to tie it to the tree or palm is flexible (like lengths of nylon stocking or stretchable grafting tape) or alternatively cut away the string or wire supporting the plant once the orchid’s roots have attached themselves to the bark. Coconut rope is a good material to use because it naturally rots away during the course of the rainy season. If the orchid is already rooted onto a tree fern slab, then you can nail that to the tree.

Finally, good hygiene is another important factor in orchid growing. If you are growing orchids in pots, keep them clear of dead leaves and debris so they can’t harbour snails and slugs, and prune away dead flower canes and leaves. This will also help to stop the transmission of pests and diseases from other plants in the garden and minimise the amount of pest control spraying that you may otherwise have to do.

All images: © Russell Fox