Betula species / Birch Species Guide
Birches are one of the toughest and most tolerant genera of deciduous trees and are generally the first species to establish themselves on the edges of woodland or on wasteland. As they are very common in the UK and Europe, they are often attempted for bonsai but are a very difficult and frustrating species to use.
Ease of Cultivation 7/10 Suitablity for Bonsai Styling 4/10
Position Full sun. It is very important that Birch receive plenty of light and that the tree is rotated regularly so that all areas of the tree equal amounts of light. Provide some frost protection from temperatures below -7 to -8°C to avoid twig die-back.
Feeding To help restrain coarse Spring growth, do not feed until 3 or 4 weeks after growth commences in Spring unless vigorous growth is required.
Repotting Every two years in Spring as buds extend, use a free-draining soil mix. Do not rootprune Birch too early; it is better to rootprune a little late after the new buds have opened than it is to rootprune while still dormant.
Pruning Prune back new shoots to 2-3 leaves after flushes of growth through the growing season. Hard pruning can be carried out from budburst in Spring until late Summer but ensure wounds are well sealed as Birch bleed heavily and are prone to die-back around large cut areas, dieback of the trunk can often spread the length of the trunk.
Try to avoid doing any pruning while the tree is not in active growth to reduce the possibility of dieback.
Strong and healthy Birch can be defoliated in Summer.
Propagation Sow seed outside in Autumn (unless of known wild origin, seed will nearly always produce hybrid plants). Root softwood cuttings in Summer.
Pests and Diseases Birch leaf-rust can be troublesome, aphids and mildew.
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