Air-layering of bonsai is used in bonsai styling as a technique to improve the quality of the trees. Sometimes a long trunk is shortened or a new prebonsai is won. A bad root basis of a bonsai or a malformation of the trunk is more often corrected by air-layering.
Shorten long trunk: Sometimes bonsai or prebonsai have a good crown, but an excessively long stem (distance between the surface of the soil and the 1st main branch is too great). By air-layering the bonsai, ie. new roots forming higher, the trunk can be shortened after removing the old roots. The proportion of the bonsai can be significantly improved and at the same time there is the possibility of making a great root basis.
A new bonsai plant can also be obtained from the branch of a normal tree by air-layering. In this way, a good prebonsai can be obtained in a few months.
Bad root basis (= Nebari): The root basis does not correspond to the quality requirements (e.g. uneven, one-sided) and should be improved. If a root basis is so bad that it cannot be improved by other techniques, air-layering of the bonsai is a way to get a completely new root basis up a little further up on the trunk. This works very well with many deciduous trees (azalea bonsai, elm bonsai, maple bonsai).
Trunk malformations: If the trunk has a malformations that cannot be corrected otherwise (for example a bulbous trunk, i.e. the trunk tapers towards the roots) bonsai air-layering can be used to create a new root basis over the malformation. After root formation and removal of the malformed trunk below the air-layering site the tree can be repotted in a bonsai pot without the blemish.
Sometimes, as with us in our bonsai nursery, the air-layering of bonsai is used on a larger scale in bonsai cultivation. From the start prebonsai with good roots can be produced in this way.