The night-time temperatures are an important factor when used for bonsai. The more tropical may perform well enough in the ground in a frost-free environment, but because we prune and trim bonsai, the branch or branches may die-back if the night temperature fall below about 18 deg. This situation occurs with Ficus macrophylla the Brisbane, sub-tropical Moreton Bay Fig when grown in Sydney, the loss of a major branch can totally wreck a styled plant. The Benjamin group for instance responds well in the sub-tropics but is apt to self-defoliate in the warm Temperate Zone.
The reason most people remove the leaves is to reduce their size. Defoliating them at the start of the growing season, will result with as large or larger leaves as before, and is a waste of the plant energy.
Another little realised use for the removal of fig leaves is for refinement purpose. A refined ficus is one with uniform leaf size. The leaves are totally removed at the end of December, allowing enough time for regeneration before slowing down towards autumn.
In growing back their size will be similar. As the ensuing tip bud enlarges it is, in fact several leaves furled around each other. By twisting this shoot between the thumb and index finger, and removing about two leaves is slowing the growth. It is also shortening the internodal length and thus continuing the refinements procedure. The now, tiny exposed leaf becomes premature, for it would have opened out in about two weeks, will thus be more in uniform with the rest.
This information should only be used when the bonsai is well structured. That means the trunk appears think for the height and the branch ramification is adequate. Unless the above criteria are already present, in the long run, you will not be doing justice to the plant.
Looking back over the spring growing period, I feel it appropriate to explain ‘pruning’ terminology, as often one may become confused about the purpose intended. eg. pruning is not cutting the twiggy ends.
PRUNING - Severing thicker twigs, branches or trunks. This is accomplished by using a saw, secateurs, loppers, as a stub should be left for a few months to dry before using an angled bonsai cutter to gouge away a depression. Heavy pruning sometimes means cutting back to bare wood. This usually applies to deciduous species before new growth commences otherwise the region may die back to a foliaged section. If unsure it’s safer to go back to foliage.
TRIMMING – The cutting away of thin/ fine twigs and branchlets. This is more efficiently accomplished with long, pointed scissors, or tiny angled cutters. The purpose is to shorten the internodes and cause division of the twiglets.
DEFOLIATION – This means the complete removal of foliage. This is usually applied to leafy plants. The main purpose is to reduce the leaf size after the spring growth has matured. In the Southern Hemisphere this can be December to mid January but before the autumn growth appears, which the latitude will determine. It is most unwise to apply complete defoliation on conifers, as foliage does not necessarily return. The leaves of broadleaf plants and Australian Natives can be removed prior to end of dormancy, advantage being fresh and unblemished foliage. The leaf stalk can be retained for further photosynthesis to take place. Use fine pointed scissors or rebound cutters for best results.
LEAF TRIMMING. – Is the progressive removal of the larger leaves that are then replaced by a smaller crop. Some foliage can come away by pulling the leaf forward without removing the dormant base bud. The point though is not to pull the leaf back toward the trunk. The resultant damage removes the replacement leaf when the bud is removed. The skinning of the skin can also cause ringbarking.
The continuing development details of English Holly dug from the ground after approx. 12 years, plus 3 prior years grown in a nursery pot had suckered & some selected for inclusion for "style" when transferred to bonsai containers for transitory appreciation. (I like to develop plants to a style to suit the container)
By this time the "Spring" growth was allowed to grow-out until the following late Winter when again cut-back quite short. This procedure continued until the late 80's.
A Summer semi dormancy occurs in December in Sydney prior to re-growth about the middle of January. The "Spring" shoots that were shortened back to a point past the previous cut a few weeks ago, by now are starting to re-shoot. This growth goes once again through winter where the cycle continues.
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