Defoliation is the complete or partial removal of the leaves of a bonsai tree. The technique is used to reduce the leaf size thus making the replacement leaves smaller and in better scale to the tree's size. Defoliation is often done 3 weeks prior to exhibiting or photographing the tree. Another benefit of defoliation is the increase in branch ramification that occurs with defoliation.

How to defoliate

The process of defoliation is simple; using a sharp scissors cut off each leaf leaving the petiole or stem. This may take a few seconds on a very small tree or many hours on a large tree.

Each cut will bleed a small amount of white latex which is normal and not of any concern. In two to four weeks the tree will begin putting out new leaves. Many of these new leaves will be in areas of the tree that never had any foliage. This process is called creating back-buds. If done properly each twig may develop anywhere from none to three new branchlets on each branch. Back-budding is a really nice help to creating more twig density on the tree and advancing the look of maturity.

Most of the new leaves will simply replace the old ones, but the new leaves will be much smaller, cleaner and undamaged making the bonsai look very refreshed. After the first new leaf emerges and enlarges, a second and third leaf will shortly emerge.

As each successive leaf emerges and hardens off it will be larger than its predecessor. Usually by the fourth new leaf the plant's normal leaf size is reached. All growth after that point will be of the normally sized leaf. If you wish to keep the leaves small you must stop the growth after the second or third new leaf by pinching all the tips back. This will hold the plant another two weeks until growth starts again. Unfortunately, this second growth will usually be with normally large leaves.

How often to defoliate

In tropical areas the fig may be leaf pruned or defoliated two, three or more times per year. But these trees are under ideal growing conditions. and are much stronger and able to tolerate the stress of defoliation.

Defoliation is a stress

Any defoliation whether partial or complete is a stress to the tree. All green plant with leaves needs the leaves to photosynthesize. Photosynthesis is the only source of energy for green plants to grow and survive. When leaves are removed photosynthesis is greatly reduced until new leaves equal to the ones removed are replaced on the tree. Thus the tree must use its stored energy reserves in the branches, trunks, and roots to survive and eventually to replace all the removed leaves. Until this happens the tree is in deficit mode. The stores are depleted and can only be restored after the new leaves come out and begin photosynthesizing for several months. Should the tree be further stressed by chilling, over watering, insects etc. the whole tree or parts of it may die.

Care after defoliation

After defoliating the tree must be kept in its normal position in light. If the tree is moved to less light the new leaves may actually grow out larger than the original leaves. Watering is reduced since the tree without leaves will not require a normal amount of water. Keeping the tree wet may result in root rot and damage to the tree. No fertilization of the tree is required until the tree puts out at least two new leaves on its growth points.

Do not repot the tree after defoliation; if a change of pot is needed this should be done two months or more before or after defoliation. The double stress of simultaneous repotting and defoliation is not advised.

When to defoliate

Defoliate when the tree is actively growing. If the tree is under stress such as disease, insects, change of location, large changes in temperature then do not defoliate.

Partial defoliation

Defoliation of only some of the tree is used in specific circumstances. Sometimes one branch of a tree is thinner or weaker than it should be. Defoliate the whole tree but leave the weak branch alone. This will allows the weak branch to grow more vigorously and catch up with the defoliated portions of the tree. The non-defoliated branch will continue to grow while the defoliated branches are busy putting out new leaves and not thickening quite as much. Done repetitively over a few years a thin branch can catch up to its neighbors.

When a tree needs some leaf reduction but the tree is not splendidly healthy it may be possible to remove the largest leaves over the whole tree. This weakens the tree slightly and the replacement leaves may be smaller. Also some trees will have an assortment of leaf sizes present. By removing only the large leaves the whole tree is brought into more harmony.

A third option is to cut all the leaves on the tree in half. Most figs will respond by sending out new leaves that are smaller but not as small as with total defoliation. It's a less stressful means to reduce the leaf size but probably the leaf size reduction is less than maximum. During this time the tree also looks quite scruffy since it has rather funny cut leaves. These cut leaves are removed after the new leaves are hardened off.

Signs of problems:

• The tree takes longer than 2-3 weeks to begin growing new leaves.

• The replacement leaves are larger than the originals.

• The tree does not re-foliate.

• The tree re-foliates on some branches and not others.

• Twig die back occurs.

• Likely the tree was not as healthy as it should have been. Do not do anything more to stress the tree and allow it grow for one year without interference.

Conclusion

Defoliation is a fabulous tool when used properly. Defoliation is not for all trees and should not be done by beginners until they are confident in their horticultural skills. Properly done it can speed up the process of advancing your tree to a higher level.