Birth trees are native to the temperate and cold regions in the Northern Hemisphere. Many birth species are from Asia and North America.
Birch (Betula sp.) is very long-lived, and can live to around 100 years. Its bark is golden brown when young, it becomes white when the birch is aging. The bark looks like sheets of paper. The leaf shape is triangular.
There are eleven common species of birch tree. Some species which are commonly used for bonsai:
- Betula pubescens (aka downy birch)
- Betula pendula (aka Silver birch, weeping birch)
- Betula alleghaniensis (aka yellow birch, golden birch, or swamp birch)
- Betula platyphylla (aka Japanese white birch)
Birch requires a lot of light, so locate in a sunny position. It does not need to be protected from the wind unless in a very exposed area.
Water lightly but frequently. Japanese White Birch requires more water, so water moderately and frequently.
Prune the shoots: During the growing season from March to November. When the branch has issued 3-5 pairs of leaves, prune the leaves leaving a pair or two.
Prune the branches: If the bonsai begins to lose its structure during the growing season, cut the branches short to maintain the structure.
Prune Structure: Only prune to alter the shape of the bonsai birch tree early on. I may not respond well to being cut once it has matured.
Repot birch every 2 years in spring. Cut away the half of the roots.
Wait for two months after repotting before feeding to allow the tree to recover.
Remove any dead branches as they appear. Keep any soil surface moss under control – ensure it does not rise to the trunk.
Wire the bonsai in winter for no more than 6 months.
Birch bark is thin and fragile and should be protected using raffia when wiring.
Recommended soil mix: 1/2 vegetal soil, 1/4 river sand, 1/4 loam.
Feed birch during the growing season, spring through fall.
Use slow release organic fertilizer. Do not give the fertilizer if the bonsai is sick.
Protect the tree if temperatures will drop below 20°F-7°C
Pest and diseases
Be vigilante for aphids and mildew, which can commonly affect bonsai birch trees.