Updated 2019/06/05
Winter is here. It’s getting colder and the rain season started (Cape Town) with lots of wind and rain.
For those that are not sure about their trees keep in mind that deciduous trees (Acacias, Maples, Swamps, elms and White stinkwoods) will lose their leaves. Tropical trees like Figs will also lose a lot of their leaves. Some trees of the same species, can lose their leaves earlier than others. This is influenced by time of defoliation, position (warm protected areas, indoors, outdoors), pruning as well as disease.
Keep a watchful eye on your trees. Even though it’s raining a lot, there are still dry spells in which trees can dry out. Even though some of your trees may be dormant they still need water to survive. See that trees standing in protected areas, like patio’s etc, get enough water. Often placing trees near or next to your house to protect them from the wind can result in them not getting any rain and they will dry out.
Protect your trees from the wind. Strong winds can blow your trees of the shelves, breaking of branches and damaging pots. Tie the trees to the shelves with wire or rope.
Make sure that your bonsai pots drain properly. Often the drainage holes can get blocked by snails (remove them from the drainage hole) or by the activities of earthworms breaking down the organic matter in your soil mix (use a stick to open the drainage hole without disturbing the roots). If your pots don’t drain properly tilt the pot and place something under it to help drain water from the pot. If your bonsai’s soil does not drain well it’s an indication that you need to repot it.
Many bonsai growers are using akadama and some are the proud owners of imported trees planted in akadama. Keep track of the condition of the akadama. Akadama break down over a period of time. Akadama breaking down (over a period of years – depending on the type of akadama) help with the refinement of bonsai, i.e. reduction of leave size etc. But the downside is that because of the breaking down process watering needs to be monitored and controlled. Since it’s a widely discussed topic with many different opinions I’m not going to go into the processes in this article. Search the internet or speak to experience bonsai growers regarding the use and effects/properties of akadama. Terry Erasmus from Bonsai Tree will also be good source of info – and as a bonus he sells akadama.
Don’t feed deciduous trees, but evergreens showing growth can be fed. You can feed your pines.
Do not prune any of the deciduous trees yet. Pruning can be done from the end of the month if you got a lot of trees and need to extend your potting and pruning period. Rather wait till early July before pruning. Trees need their rest and by pruning them too early you place them under unnecessary stress. Pruning deciduous trees now will cause the trees to start pushing new buds if the weather gives us a warm period. New buds will only weaken the tree before they will stop developing or even die off during the winter. It takes a lot of energy from the tree to develop new growth. The tree will also not get enough rest and this can cause smaller branches to die back.
Remove dead leaves from your pots. They only create a place for bugs and diseases to hide.
You can now needle pluck, design and prune your Japanese black Pines.
Junipers can be wired pruned and styled. Now’s a good time to do large bends on Junipers. Wrap brunches with raffia to protect them during the bending process.
Do not pot any trees at this stage. Start preparing your soil mix for the repotting season. Do a bit of research on soil mixtures so that when repotting season starts you can be prepared to make informed decisions when potting your trees and you can make corrections to trees that needed a change in their soil mixtures. Try to keep your soil mix out of the rain. (Don’t pot with a soggy soil mix. )
Early next month you can start with potting swamps, white stinkwoods and at the end of the month, elms.
Remove moss from trees with soft bark, like cork bark elms, acacia etc. Leaving the moss on the trunks will cause the bark to rot. Also remove moss from the soil. Moss retains a lot of moisture in the soil which can cause root rot on trees like olives. Don’t throw the moss away. Place it in single layers in shallow containers under the bonsai bench. You can use it in landscapes etc. Moss can be killed by spraying it with vinegar and then carefully removing it with tweezers.
Be careful when you wire trees this time of the year. Branches are very brittle and can break easily. Be careful when bending branches.
Deciduous trees that already lost their leaves can be sprayed with diluted lime sulfur. Mix the lime sulfur with water in a ratio of 1 part lime sulfur to 30 parts water. This mixture ratio won’t stain unglazed bonsai pots much. You can use much stronger mixtures but it will stain unglazed pots. Spraying deciduous trees with lime sulfur while they are dormant will kill off unwanted pests and their eggs as well as other diseases. Lime sulfur will also help with the control of fungal diseases like anthracnose. Cover unglazed pots when you spray the trees with something like glad wrap to prevent the lime sulfur from staining these pots. Repeat the spray after 10 days. Lime sulfur can burn/damage new growth.
Spray your olives with a preventative spray for root rot.
Start shopping around for new potential bonsai stock. Most of the trees in nurseries already stopped developing and are only putting down hard wood, increasing their trunks. Shop around to be first to find the best stock.
Remove your trees from the shelves and clean the shelves of old leaves and dirt and you can also disinfect the shelves with a strong Jeyes fluid mix. Place it in a spray can and spray the benches with it. Only replace your trees on the bench after the smell has faded.
Some trees like Azaleas will flower from middle to end of June. Remember to remove spent flowers.
Another topic that I need to discuss: Feeding of sick or stressed or newly repotted trees.
Trees manufacture food from ‘dissolved chemicals’ (what we call ‘plant food’) that it absorbs from the soil (process of osmoses). The tree then transports it to the leaves where the tree makes use of sunlight to manufacture food from these ‘dissolved chemicals (photo synthesis).’ This food is then distributed to the rest of the tree on which it feeds and grows.
Trees are NOT like human beings whom you feed chicken soup to when they are sick to get their strength back. Trees make their own food (photosynthesis). But a sick tree, newly repotted tree or stressed tree cannot take up these ‘dissolved chemicals’ if they are sick or under stress (osmoses). We often like to give trees human qualities/characteristics and want to feed sick or stressed trees back to health. It does not work like that. Feeding sick or stressed trees will only increase the ‘dissolved chemicals’ in the soil. Adding more dissolved chemicals (‘plant food’) into the soil will cause a process called reverse osmoses which will further damage the tree. This also goes for foliar spray/feeding.
Plant food as we buy it from the shops isn’t “food” for plants. It’s part of the chemicals necessary to produce food, which only the tree can change through photo synthesis into food.
Without leaves the tree cannot make use of the process of photosynthesis to manufacture food and all the ‘plant food’ that you feed your trees will wash away or accumulate in the soil.
In short – don’t feed sick or stressed trees, newly repotted trees or trees without leaves. There are a few chemicals that can be applied to help stressed/sick trees but first ask an experience grower before applying it to the tree.
Again – Don’t feed sick or stressed or newly repotted trees.
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