Every now and then, someone asks “Why do orchids like to be pot-bound, when they aren’t enclosed in any pot in nature?”. There are lots of theories related to aeration and water-holding capacity being diminished in a pot that’s full of roots, but I believe we are missing the mark. In a pot or on a tree, the plants have the same sets of needs, and one of them is mechanical stability.
Most plants in the wild don’t grow in confined spaces…true. Their roots spread out in all directions, where they attach to the host tree, providing mechanical stability, helping maintain their niche, so they can grow and multiply. A plant that is not well-anchored is at risk of being washed out of its host by a downpour or blown out of it by wind. At that point, they will fall into a grass and leaf litter below and likely die. Not exactly what’s best for carrying on the genetics.
A plant that is not established in a pot is in an equally vulnerable state, so puts its efforts into getting there, by growing roots instead of shoots and flowers. Once it is “comfortable”, away it goes as we prefer, with good growth and blooming.
A phalaenopsis for example, when in a small pot, produces lots of aerial roots. Put them in a much bigger pot and the roots all grow down into the medium. Mount them and the roots reach out until they make contact with the mount and attach to it.
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