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Some Observations of Epiphytic Orchids
There are many kinds of orchids, but epiphytic orchids are my favorites and Cattleyas top the list. An epiphyte is a plant that grows on another plant. In nature, epiphytic orchids mostly grow on the sides of trees. Many epiphytic orchids have been growing this way for 15 or so million years. To put this into perspective, Homo sapiens (that’s us) appeared around 300,000 years ago, and the most modern human evolution state is now the Orchid hobbyist which appeared about 125 years ago.
Thus, epiphytic orchids have been here for over 14 million years before the first humans even appeared on the planet! Humbling to say the least. Due to their millions of years growing on the sides of trees, orchids have evolved to grow well in these conditions. Even with climatic changes and seasonal weather variances, they continue to prosper and thrive on the sides of trees.
Understanding why orchids grow the way they do will help us make better decisions about how to care for them and allow us to be more successful in our passion, our orchids! Every orchid species has a set of environmental conditions it grows in. Learning about their environmental habitats, including the seasonal rain fall, temperature, and light, and then applying a similar practice in the cultivation of your own plants will help you achieve good plant growth and the better flowering you desire.
For example, I have observed the following about orchids growing on trees:
- Epiphytic orchids live on the sides of trees
- The sides of trees are well drained
- Orchids roots are well drained
- Orchid roots evolved in the presence of organic matter
- The leaves and roots of the orchid plants get a lot of air circulation
- The tree surface dries out quickly, as do the leaves and roots of the orchids
- There is not a lot of nutrients on the side of a tree: it’s a low nutrient location
- Orchid roots have become good at capturing moisture and nutrients.
These observations about life on a tree, coupled with acknowledging their long and successful lifespan on this planet, have inspired me to try and implement this same environment for my own plants’ root systems to the greatest extent possible.
That is why for epiphytic orchids using organic potting media is a good approach, in my case a bark and Perlite mix. A freely draining bark mix can simulate the well-drained nature of the sides of trees. The potting media must allow for air movement around the roots, so the roots dry out quickly. The roots need to dry out like they do on the sides of trees.
Orchids in nature live in a low nutrient environment. The few nutrients that are available are brought to the root system by each rain event. Because of this scarcity and the necessity of water and nutrients to survive, orchid roots have become excellent at absorbing both. Thus, using just a small amount of fertilizer, equivalent to ½ tsp fertilizer per gallon water at every watering will duplicate what happens in nature.
There is something else about orchids and trees. Although the orchid plants themselves are stationary, their roots can extend many feet from the plant in their quest to acquire resources like water and nutrients. The job of the roots is to absorb water and nutrients for the plant. Since the plant is stationary, the roots must find what they need where they are growing, and they have gotten exceptionally good at doing so. I have noticed that roots favor the environment and location they formed in. You may have observed this phenomenon for yourself. Have you taken a plant with healthy air-roots and potted them? How well did those air-roots survive the change? What about transitioning a well-rooted potted orchid plant to a mount? How did those roots that formed in the growing media do when tied to a mount and exposed to the air? Did they thrive? Or decline? Likely, they declined, because an orchid plant has evolved for its roots to stay in the environment they formed in (they don’t move from the location they are in). For the roots to do well in a new location (being re-potted), the orchid plant must form a new set of roots in the new conditions (new pot and media).
But what does all this mean? It boils down to the main goal of all of us orchid lovers – raising healthy plants that produce beautiful blooms. Here are some important guidelines based on how plants grow in nature that you can use for when to re-pot your epiphytes. Remember, when you re-pot, you are changing the root zone environment, and we have established that the roots do not like the change. Therefore, we need to find a time when the plant is best able to adapt to re-potting. That time is when new roots are starting to emerge from the rhizome. This is not to be confused with new pseudobulb growth. While some orchids form new roots as the new pseudobulb develops, many orchids grow their new roots after the most recent growth has matured. This requires that you look for new roots rather than new growths. As soon as you see new roots developing from the rhizome, this is the time to re-pot. The newly developing roots will re-establish the plant in the new potting media, enabling it to adapt and taking over from the roots that developed in the previous potting media.
Understanding the timing of when your plants make new roots is important information, it allows you to make good decisions on when is the right time to re-pot.
*A valuable tip: on the pot tag, write the date when new roots start to emerge. After a while you will have a list of dates on the tag indicating when is the best time to re-pot.
After you start this practice of “when roots emerge awareness” it becomes indispensable, and you will soon realize it enables you to predict and make informed decisions on when new or unknown plants will most likely root so they can have the best opportunity to thrive under your care.
A healthy root system is a key component of abundant growth and flowering. Epiphytic orchids are survivors. They can tolerate many harsh conditions, and they are surprisingly adaptable, yet they will fare better and reward you more with their beauty if they are not subjected to a “survivalist challenge.” The stability of root zone environment is important to your orchid’s health, and you support its health by only repotting with the onset of new roots. When choosing a potting media, be sure that the media has an organic component, has a stable pH over the life of the potting cycle, is well drained, and dries out quickly. As much as possible it should mirror the orchid’s favored environment.
It only taken me 30 years to develop this understanding of why epiphyte orchids grow the way they do. I believe sharing this natural process can only result in making you a better grower.
Good Growing!
Fred Clarke
Fred Clarke, Sunset Valley Orchids
