Birch
(Betula)
Country of Origin : North America, Europe and Parts of Asia
Bonsai Styles : Informal upright, twin-trunk, group
Zone : 2 – 6
Birches are not very often trained by Chinese or Japanese bonsai enthusiasts, however birch trees are increasingly trained in the West for bonsai.
In fact, not long ago, birch bonsai trees were not even available commercially to buy, unlike now.
In addition to growing well in Bonsai pots, birch trees offer nearly everything a Bonsai enthusiast might desire.
With slender lines, attractive bark, and delicate leaves, birch trees make stunning bonsai plants. Birches have graceful shapes with flexible twigs that swing in the breeze.
Birch bonsai tree is mainly grown for its attractive bark. However, it should be noted that it takes a long time for the bark to turn white. As trees age, their bark becomes rougher and blacker in color.
The bark of birches peels off and the catkins are pendulous. A pigment called betulin gives many birches their distinctive white bark.
It has alternate, toothed leaves that are usually ovate and green in color.
Birch is a deciduous tree. Birches are green and leafy during the growing season. After turning yellow over autumn, their leaves drop over winter.
Some of the varieties used for making a birch bonsai are :
- Dwarf Birch – Betula nana. It is a dwarf version of birch tree. Its not only preferred for its small size but also it can be trained in many more bonsai styles when compared to regular birch tree.
- European White Birch – Betula pendula. It is also known as silver birch or common birch. Unlike its American counter-parts (e.g. paper birch), its leaves are more triangular, and darker & less flaky bark. Also, its trunk has vertical cracks which are not that prominent in American birches.
One of the things which makes this bonsai a little challenging for beginners, is that its branches will dieback randomly. This makes it hard for maintaining the desired shape and style of the birch bonsai.
The lost branches will grow back again, as these trees are quick growers.
It is possible to grow birches in the south, such as yellow birches and sweet birches, but most prefer cooler climates.
Mainly suitable for large bonsai style.
Read more about other bonsai trees species in : Bonsai tree care
Best location to keep Birch Bonsai
Birch bonsai tree does not do well in shade, hence this is not a good candidate in case you are looking for an indoor bonsai tree.
It can be placed in full sun or partial shade. Partial shade from direct sunlight in hot days.
The birch tree is hardy and frost tolerant (one of the most frost hardy species). However, protect them from cold winds to prevent twig die-back.
A decent temperature range in the time of growing season is 68°F and 86°F (20°C to 30°C).
Hot temperatures will damage the tree. Remember that this is a tree for cold climates.
The tree will die if the temperature reaches 113°F (45°C).
IMP: Refer sunlight requirements for indoor plants for more indoor gardening ideas. Also, refer to do bonsai trees need sunlight for more indoor and outdoor bonsai location ideas.
Propagation of Birch
Birch can be propagated through seeds and cuttings. However, it is wise to remember that achieving rooting of cuttings can be a little challenging.
Seeds can be sown in fall.
Semi hardwood stem cuttings can be used in summer.
If you want to get the best results, you should collect wild Birch in the spring just before or just after the first leaves appear.
Watering Birch Bonsai
Birch tree needs a lot of water. From spring to autumn, birches require daily watering.
During hot, sunny days, you might need to water them twice a day.
You can even keep the bonsai container in a shallow tray of water to keep the supply of water consistent.
During the winter, the compost should be kept just moist.
It is important to keep in mind, however, that the cooler the location, the less water will be needed.
Read watering bonsai tree for more details.
Wiring Birch Bonsai
In some cases, the major branches may need to be wired to emphasize their shape, but this is rarely necessary.
You should only wire branches that have hardened slightly if you have to wire them.
The wiring of newly formed shoots can cause these shoots to die back, and the wiring during winter (when the wires will chill the plant) can also have the same effect.
There is a risk of the wires marking the trees if they are left on for more than a year.
Use a guy wire.
Some time using hanging weights to shape the branches of birch is more appropriate than wiring the branches.
Pruning Birch Bonsai
When to prune Birch bonsai?
How to prune Birch bonsai?
Each year in the spring, you should cut back birch bonsai to the old wood to encourage the growth of new shoots.
For the best results, it should be pruned regularly throughout spring and summer in order to encourage fine branching.
In the summer, Birches that are strong and healthy can be defoliated.
It is recommended to pinch out the growing tips of new shoots when two or three leaves have formed, and to continue doing so throughout the growing season.
If you make large cuts in the wood while pruning, the wood will rot quickly. There is a tendency for the trunk to become hollow as a result of this.
Do not prune the Betula bonsai when it is not in active growth. Pruning birch trees out of season can cause the trees to “bleed” to death.
It is important to ensure that the pruning wounds produced by this pruning process are well sealed. Birch trees bleed heavily and are prone to die-back around large cut areas. This die-back of the trunk can often spread along its length.
This will lead to unsightly deadwood on the trunk. Moreover, it is highly likely to rot.
Make clean cuts with a fine-toothed bonsai saw when cutting large branches. This will help in relatively better healing of the wound.
Repotting Birch Bonsai
When to repot Birch bonsai?
Betula bonsai can be repotted in early spring, every 3 to 4 years.
The tree also does well with root pruning. Do not remove more than 1/4th of the total root system while repotting.
However, remember that root pruning is advisable only when the new buds have opened. Hence time your repotting accordingly.
It is very important that the compost used for repotting is well drained and moisture retaining at the same time.
You can also apply some top dressing after filling the bonsai soil. Mix equal parts of sphagnum moss and green moss to make top dressing.
You can use a basic free-draining bonsai soil mix as a potting soil.
OR
Use a soil mix with sand, peat moss and loam at the ratio of 1:1:1.
Must Read: Bonsai Soil Recipes
Must read : Choosing the right bonsai container
Feeding Birch Bonsai
Once a month throughout the growing season, apply a weak fertilizer to the bonsai.
Read more about bonsai fertilizer and its application.
Diseases and pest of Birch Bonsai
The best way to control aphids is to apply a systemic insecticide. You can even remove them manually or use a gentle water jet to dislodge them.
In addition, it is important to note that birch trees are also susceptible to a dangerous disease called honey fungus that needs to be treated with a fungicide as soon as symptoms are observed. Remove the infected part of the tree.
Birch trees are frequently attacked by insects like the bronze birch borer (birch leaf miner). You need to make sure that pruning and removing of damaged or dead branches is done on a regular basis. A systemic insecticide containing imidacloprid or dinotefuran can be applied to the birch tree for prevention.
Also, Birch leaf-rust can cause some problems. Applying some copper fungicide in spring (before buds open), can prevent the disease from occurring.
Birch bonsai care
The branch die-back of these species is common; it should be cut back hard to healthy tissue and pruned to establish a new framework of branches.
The branches and stem of trees should be pruned regularly according to the season, so as to prevent any disease or infestation from developing.
The reason that birches do not last long as bonsai is because their trunks rot easily; replanting them in open ground from time to time will be able to rejuvenate a tired bonsai tree.
When birches have strong top growth, their lower branches tend to drop. Keeping top growth in check and preventing strong shoots from growing at the top of a tree will prevent branch dieback.
