The Bonsai Grower in Winter

By Lionel Theron

Winter is the time when bonsai trees are resting and are dormant. It is also the time when bonsai growers may not feel very inclined to be outdoors in the elements, but would prefer to be sitting in front of the fire with a warm drink reading and absorbing ideas from the many bonsai books and magazines that are available. It is a time to watch the many bonsai videos that are available. These somewhat passive and enjoyable bonsai activities are both stimulating and motivating; Visiting bonsai collections, nurseries, attending club meetings and workshops and generally exchanging ideas are very important for the bonsai lover who wishes to make progress in this absorbing art form.



The wet weather will have brought the mosses into their full green finery, and it is time to collect from gutters, road verges, southern slopes of banks, rocks and walls. It is important to leave bits of moss in order that the collecting spots may regenerate before the next collecting trip. There are many different mosses, and the observant person will be rewarded with the joy of all the different hues and textures.


All the ingredients for soil mixes should, by now, have been collected. It is an unpleasant job to collect when soil and compost is mud! Soil mixes should be stored in a dry place, ready for use. Most local soils are deficient in potash and phosphates and these may be added to the soil in the form of super-phosphate, bone meal, hoof and horn meal or potassium sulfate which is obtainable from nurseries. Peat should be added to the potting mix of plants that are acid lovers, such as; azaleas and maples.


It is useful to be on the lookout for rocks at all times especially when out for drives, and to collect any interesting and unusual stones which form an important adjunct to bonsai. Rocks are used on their own; as suiseki, as part of penjing or saikei or for root over rock etc. Suiseki, can particularly be enjoyed as an indoor recreation. Whilst out in the open one may enjoy nature, and one of the ways in which we can contribute to our environment is to plant a few seeds. It is especially important for those of us that collect trees from the wild to do our bit in restoring our surroundings. If possible, replace more than is taken.


Many of the trace elements in the soil in which our trees are potted are leached out by all the rain which we experience in winter. Selective light feeding of evergreens will combat the effects of this deficiency, but avoid heavy applications of nitrogenous feeds. It is also a good time to replace some of the phosphates by the application of superphosphate, On a clear, non-rainy day one may spray with a trace element mix such as Trelmix or Nitrosol.


Choosing pots is an enjoyable pastime, and gone are the days when there were shortages of pots, nurseries now have good stocks of pots from all over the Far East. It is very satisfying to have a good range of pots in store from which to choose exactly the correct one when one comes to potting a tree.

The first deciduous trees to be potted, in early July are; Taxodium (Swamp or Bald Cypress), Celtis (White Stinkwood & Chinese Hackberry). These are followed by; Acers (Maples) and deciduous fruits, a little later the Ulmus (Elms). Acacias are potted somewhat later when leaf buds are swollen but before the leaves unfurl. Azaleas are potted immediately after flowering, but before the new growth emerges.

This is a good time to visit nurseries as they usually have good stocks of starter material and the structure of branches on leafless trees is clearly seen.

July and August are our coldest months and evergreens are not potted until later; about October. It is usually better to wait until buds are well swollen or in some cases, for the plants to be growing strongly.


Many pests are active during winter, we do not experience such low temperatures that pests are frozen, and some pests such as scale are readily discernible whilst trees are bare. A spray program can be helpful destroying spores and prolific progenitors of next seasons unwelcome pests. Aphids, mites and the small sucking insects such as scale and meallybug which often go unnoticed until they have caused considerable damage may now be destroyed by spraying with Folithion. Useful sprays for fungus are Funginex and Virikop whilst Rosecare is a combined insecticide and fungicide. Snails and slugs love the damp weather and these can be controlled by hand picking or using one of the many baits which are on the market.


This is a good time to check tools that they are clean, sharp and operating properly.


Cold days are not in necessarily wet, fact they can be quite dry. Be very careful to water if necessary. More bonsai are killed through lack of water than for any other reason and the combination of cold and dry is intolerable to many plants.

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Pools in the rocks

Softly tinted russet red and brown

Autumn is near

Random Bonsai Tip

When you have too thin trunks, you could twist two or three saplings together, fasten them together with wire and allow them time to fuse; or graft two trunks together.