You may have heard that orchids are epiphytes, and that might leave you wondering if all orchids are, or whether some varieties are not. It might also lead you to question how they evolved that way, and what that really involves. So, are orchids epiphytes?
Most orchids are epiphytes, yes, and many of those that are not tend to grow on rocks or even in water, rather than in soil as many plants do (although some orchids do grow in soil, too). It is thought that around seventy percent of orchids are epiphytes, growing on trees instead of in the soil or at ground level.
What Are Epiphytes?
Epiphytes grow on the surface of a plant, but they are not parasitic. Instead, they draw nutrients and water from the air, the surface of the host plant’s bark or stem, or from debris that collects around the roots of the epiphyte.
Epiphytes do not harm the plant that they grow on and don’t steal from it in any way. Instead, they use it as a support, often to get themselves away from dense foliage below and closer to the source of light overhead.
This is often the case for orchids, which may choose to grow on the branches and trunks of trees as a means of getting off the forest floor. These plants take their nutrients and water from traces that wash down the trees during rainstorms, and they don’t harm the trees or steal from their energy stocks.
Only around ten percent of plants are epiphytes, and they are commonest in tropical regions where damp air makes it more viable for plants to grow on the surface of other plants. Plants that commonly have epiphyte members include bromeliads, orchids, and ferns.
In case you’re wondering why it matters, understanding where the plants come from and how they grow in the wild makes it much easier to understand how to care for them properly in our homes. Orchid growers are more likely to effectively meet their plants’ needs if they know what the plants seek in their natural environment.
What Do Epiphytes Need?
So, what general rules can we learn about orchid care by studying how epiphytes grow on the whole? Remember that these rules only apply if you have a species of orchid that is epiphytic. If your orchid is not one of these species, it might not thrive under these conditions.
Firstly, epiphytes usually have thick, spongy roots that are capable of holding onto water for longer periods than the roots of most plants that grow in the ground. Epiphytes have adapted to cope with relatively infrequent rainfalls, and therefore make the most of the water that washes over them and hold onto it.
This means you don’t need to water your orchid too often, because it is used to infrequently being drenched by a heavy rainfall. It will soak up and hold onto water in its fat roots, and shouldn’t need to drink again for some time, because this will slowly be supplied to the plant.
This root tissue is referred to as velamen, and it is designed to take in water fast and hold onto it as conditions around it dry. It is frequently breezy in the canopy of a tropical rainforest, so it dries relatively fast after rainfall.
Your orchid will probably therefore be tolerant to drought, but it is not good at staying persistently wet. Although rainforests are often humid, bear in mind that water on a tree trunk would run straight down, and the roots would never be sitting in water for more than a few minutes.
This is why orchids are vulnerable to being over-watered and won’t cope well if you give them too much to drink. A good drench infrequently is the best option for their adaptations.
Although orchids dislike sudden temperature changes and enjoy humidity, they also need a breeze or else they become vulnerable to quite a few different diseases. An orchid with perpetually damp leaves in a still room will very quickly fall prey to fungal infections, and you may lose the plant entirely.
It is a good idea to ensure that your plant enjoys some breeze most days, as this will reflect the canopy breezes that dry its leaves and keep it safe from fungi.
You can achieve this by opening windows on sunny, breezy days, spacing your plant out so that it isn’t too close to other plants, or even occasionally wafting it with a fan as you pass by. This will let you keep the plant humid without risking its health.
Obviously, one of the biggest differences between an epiphyte and a “normal” plant (that grows in soil) is its potting medium. If you try and plant an epiphytic plant in ordinary compost or any heavy growing medium, you will find that it quickly dies, because it is unable to cope with the heaviness of the soil.
Epiphytes are used to having a superb flow of oxygen over their roots – after all, these are exposed to the air more often than they are covered, although they may end up with leaf litter and debris wrapped around them.
You need to grow epiphytic plants in a suitable medium, which allows for fast drainage and good oxygen flow. Usually, orchid bark is a suitable option, sometimes mixed with other potting mediums such as perlite or perhaps a small amount of compost to provide nutrients.
Some people choose instead to wire their orchids to a piece of bark or a small branch; this allows them to enjoy their natural conditions and ensures that they don’t get too damp. However, if you don’t want to do that, you can just keep your orchid in a pot with the right growing medium. As long as the drainage is good, it should manage.
Growing beneath the canopy of a rainforest creates slightly unusual light conditions, because the orchids are high up but under often fairly dense cover from the trees that they are growing on. This means that they do not tolerate shade well, but also cannot handle direct sunlight.
You will need to keep orchids in bright but indirect light to keep them happy, which can be a challenging requirement. West or east facing windows are often a good option, or you may be able to create a shield to protect your orchid from the sun if it is suffering from too much light exposure.
Black tips on your orchid’s leaves indicate that it is burning and you need to move it away from the light. Slow growth can suggest too little light, in which case you may need to purchase a grow lamp or find a better window for your plant to grow in.
Rainforests are known for being very humid places, and this is another requirement that makes many epiphytic orchids tricky to grow. They like humidity, but as already mentioned, they are vulnerable to disease if their leaves stay wet a lot of the time and the air is still.
You can help to meet your orchid’s humidity requirements by lightly misting its leaves, or by creating a tray humidifier.
To do this, you need to fill the bottom of a tray (with no holes) with a layer of pebbles, and then top it up with water to just below the line of the pebbles. Stand your orchid’s pot on the pebbles so that the water isn’t touching the pot. Over time, the evaporating water will lightly mist the leaves, keeping your orchid happy.
You can top the tray up whenever it needs it, but keep an eye out for signs of fungus, and try to make sure your plant enjoys a reasonably regular draft to dry its leaves as well. It is a good idea to remove it from the humidifier at times to let it dry out a bit and reduce the risk of fungal infections.
Obtaining nutrients is often a little different for epiphytic orchids than for other plants. Although they do still soak up nutrients through their roots, they don’t grow deep roots, so if you put your plant in a pot, it will only use nutrients near the top, rather than growing long roots to reach the bottom.
It isn’t worth planting orchids in very deep containers for this reason. They won’t take advantage, but will mostly continue seeking nutrients near the surface of the pot, spreading their roots out.
If you have attached your orchid to a piece of bark, you will need to wash its roots with a nutrient-rich solution to provide the food it needs, as it won’t be getting this from the soil.
Not all orchids are epiphytes, but many are, and it is a good idea to establish what kind of orchid you have before you plant it so you can meet its needs as effectively as possible.
If you don’t know what kind of orchid you have, you can probably still keep it alive and well by providing somewhat tropical conditions and not over-watering it, but it may prove a little harder.