Defoliation

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Defoliation is a process applied to deciduous trees by removing the leaves, either completely or in part with the following goals:

This may be complete defoliation or partial defoliation of the canopy.

When to defoliate

  • Defoliation should be carried out after the leaves of a deciduous bonsai have hardened off in late spring. At this time the leaves may be stripped or the leaves may be cut, leaving the leaf stems (petioles) in place.
  • Weak, or unhealthy trees should not be defoliated. Conifers should not be defoliated and have their own foliage pruning techniques. (See candle pruning).
  • Do not defoliate trees that you are trying to increase the size of. Defoliation will force the tree to slow down its growth


How to defoliate

In practice, leaves are removed either by a Thinning_shears, tweezers or plucked by hand, usually beginning after the spring growth has hardened off. By removing selective leaves, the resulting regrowth will be more compact and the leaves smaller than previously grown.
The best way to defoliate is to use Trimming Scissors to cut the petiole at approximately 1/2 length and the leaf will fall away. The petiole remaining will then die back and drop off on its own.
Defoliating this way causes the least damage and disturbance to the tree.

The defoliation process will quickly force the tree to send out new leaves to replace thos lost and the new crop of leaves will typically be smaller

Regulating strength

This method can be used to redirect strength in the tree and ensure that branches in the interior and lower parts of the tree retain their vigor. For example, if leaves are removed from the crown and periphery, the interior leaves which remain will be exposed to additional light and air during the regrowth period, and so grow stronger.

Recovery after defoliation

A defoliated tree usually requires approximately one month to completely regenerate leaves. It should be well fertilized in the period immediately prior to defoliation and water must be supplied sufficiently to ensure that the tree's recovery is successful. Defoliation may actually be carried out twice in a season, but only on trees that are in perfect health. A minimum two-month recovery period should be allowed.

Within a few weeks the petioles will drop away and new leaves will appear. The regrowth will be weaker, leading to a finer ramification.

Species to defoliate

Most all deciduous trees and broadleaf evergreens can be defoliated with success, with some exceptions. Beech trees do not respond well to defoliation. Flowering trees may be forced to flower again if completely defoliated.

See this great page on Defoliating figs

Links

Great discussion on how to reduce the size of foliage
Great tutorial on How to defoliate and Root prune a Ulmus Procera
Bonsai 4 Me article on Defoliation


Types of Pruning
Pruning | Drastic pruning | Defoliation |Pinching | Trunk chop | Thinning | Trimming | Root pruning | Root trimming | Decandling
Tools for Pruning
Concave cutters | Shears | Thinning shears | Decandling shears | Leaf trimmers | Scythe | Root cutters | Branch cutters | Spherical cutters | Knob cutters