Bonsai in October This is the time to start preparing for the winter now that autumn is here. It is a chance to review your requirements and options for winter protection and prepare your trees. It is also a great time of year to admire your deciduous bonsai trees as they put on a good autumnal display. Here is a quick generic guide to bonsai in October as the colder and wet weather starts to arrive in the UK.
Preparation for Winter Check all your bonsai trees for health to ensure that before they are all in good health before the change in weather as the stronger your trees are the better chances they have of coming through the winter in good health. Ensure that before placing them under cover or into a cold greenhouse that the leaves for broadleaves have been removed as dead leaves rot and can cause mould and fungi to build up and affect the buds for next spring. The leaves should fall naturally but some species tend to hold onto their leaves longer so if they do not fall naturally then they can be removed once they have changed colour and start to fade or shrivel.
Watering Your bonsai trees will still need watering but not as often as their growth rate has slowed right down so the water uptake has also slowed down and the trees are going into winter dormancy. At this time of year if your trees are still outside, they will be getting watered naturally by the rainfall and morning dew. However, monitor the moisture level to ensure your bonsai trees are not water logged as this can cause roots to rot. If your bonsai trees are under cover check daily and water if required to keep the soil damp / moist but not soaking wet. Any bonsai being kept indoors should be watered regularly but this will have slowed down from a daily watering. They will be loosing moisture due to the higher temperatures inside drying out the soil and the tropical species still tend to grow during the winter period inside. Ideal time to water is in the morning to allow the water time to dissipate and to reduce the surface water should the temperature cool down overnight.
Re-potting This is a good time to check your bonsai supplies and soils as the repotting season is coming and it is good to have sufficient supplies in stock. If you are looking to change the pot that you have the correct pot size to repot into.
Feeding Generally feeding in October is not required as broadleaves trees are becoming dormant and are without leaves or shedding their leaves. You can continue to lightly feed conifers and evergreens during this period. Also continue to lightly feed tropical trees that are kept indoors if they are still showing signs of growth to sustain them during this period.
Pruning This is a great time of year to review your bonsai trees and check the structural image of the tree as well as the tracery and branch placement. Broadleaved trees are especially easy as they have for most species lost their leaves and are dormant. You can remove unwanted structural branches but remember to cover the wounds with wound paste or sealant as the trees are dormant and will not be able to respond to the pruning as effectively. Otherwise just mark the branch(es) to remove and wait till the Spring to then remove them. This is also a good time to carve dead wood, jins and sharis now that the leaves are starting to fall.
Trimming This is not required to broadleaved trees in October. However, you may still need to trim the new shoots off tropical trees that are growing indoors to control the growth and develop ramification. This is the best time to remove old needles from two needle pines and clean out the dead needles and carry out any structural pruning of pines.
Root pruning None required yet as not quite the repotting season.
Insects and pests Continue to check your bonsai trees over fully for pests, insects and diseases as some insects can over winter on or in your trees like red spider mite, scale insect. Pests are also likely if the weather is mild so worth checking to avoid disappointment in the spring when buds or leaves fail to flush due to pest attack. Typical pests still around include scale insect, mites, aphids and soil borne larva, vine weevil and beetles.
Moss and weed control This is the time to carry out pre winter preparation and to remove any weed and moss issues particularly around the trunks of bonsai trees prior to winter. The aim is to have a clear surface of the soil for improved moisture movement as well as prevent bark rot from wet moss. You can use a range of techniques including a diluted vinegar application on the bark which you apply and then around a week of two later the moss removes more easily with a light brush action (tooth brush works well).
Wiring If wire is present on your bonsai tree check whether it is still serving a purpose and is taught and not digging into the bark causing wire marks and re-set if necessary or tighten. This is the time to start removing , adjusting or re-applying wire. This is also a good time to wire Pines and Larches to set the branches over the winter and it is an easier time to wire certain species like broadleaved varieties as the leaves have fallen off.
Protection For those trees in your bonsai collection that are more sensitive to cold weather try to provide them with some winter protection from the frosts especially if they are in small pots. The smaller the tree the more vulnerable to winter weather damage they are. Options for protection include · Under benches · Cold greenhouse · Cold frames · Shade netting · Fleeces · Double potting placing on pot inside a larger pot · Pot protection with fleeces, polystyrene, wooden box Certain tree species are more vulnerable due to their sensitive foliage type or root type so protect species like Yews, Ginkgo’s, Ilex, Swamp Cypress and species with fleshy roots.
Propagation This is the start of the lifting season for digging trees and shrubs out of the ground in preparation to transplant them. If you are looking to collect a tree known as Yamadori then this is the start of the season to prepare trees for winter collection. This can be done by cutting a circle around the rooting area in the ground now prior to lifting the tree fully in the coming months. This is also a great time to start collecting seed in preparation for planting them up for next March in the Spring. Hardwood cuttings can also be taken in October as a method of propagating from your trees that are now not in leaf.
Assessment This is also a good time to photograph your bonsai trees and update their records for re-potting timings, feeding regimes, soil type etc as it is sometimes hard to keep track of what you do for each tree when you start increasing your collection. Keeping a photographic record does come in very useful over the years to see the trees development and your progress.