Several tropical tree species are capable of growing aerial roots. best known plant families to do this, are the ficus. when seen in their natural habitat, they grow impressive side trunks once the roots growing from the canopy reach the ground.
Why do bonsai not grow aerial roots? Ficus grown as a bonsai, do not often create aerial roots. This is because they ate in pots as many conclude. Ficus grown as bonsai in non tropical regions do normally not grow under circumstances that facilitate the development of aerial roots. Change the circumstances, and you can create aerial roots.
Circumstances that stimulate aerial roots.
When you observe trees carefully, you quickly notice the circumstances under which aerial roots develop. Trees which develop the best aerial roots in nature have the following characteristics:
– Trees with dense canopies develop areal roots. aerial roots appear from shaded parts of the tree canopy. Branches where the bark gets a lot of sun do not often grow aerial roots
– Trees growing in areas with high humidity develop aerial roots. Aerial roots develop when there is moisture for them. If the air is too dry, aerial roots do not develop.
– trees in dry or shallow soils develop aerial roots. I contribute this to limited availability of water for the tree.
So. How to stimulate aerial roots on bonsai?
If you want to get aerial roots, you should of course make sure the tree is healthy. Allow the crown to grow dense enough to have a lot of shade on the branches. Place the plant so that air humidity nears 100% and mist frequently. At the same time, keep the root ball on the dry side.