Hornbeam bonsai do come in a variety of species. From the betulaceae family of trees, this deciduous species is gracious with light green foliage but sport a muscle like bark or smooth grey color. Ironwood is a common name for hornbeam. The name ironwood comes from the ancient time when they used carpinus wood to build ship. It was an extra resistant and hard wood. In general, the hornbeam is a slow rate growing tree. The leaves will turn orange in fall and will turn brown when dry. The brown leaves will often stay attached in the winter season. Three species are popular as bonsai. Two of them are known as Korean hornbeam while the other one is known as the European Horbeam.
Carpinus Betulus
(European Hornbeam)
This species is preferred for its delicate gray bark. The leaves can grow as big as 4 inch in length. The fall color of the leaves is yellow. It is popular in bonsai for many styles. Small forest of European hornbeam are beautiful.
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Carpinus Koreana
(Korean Hornbeam)
The true Korean hornbeam. From it’s name you can conclude that it is native to Korea. For the last 20 years, Korea exported a lot of these trees collected from the forest. It is now very hard to import trees from Korea since they want to protect their native stock. The leaves are rather small and they adapt very well to bonsai techniques. It is the fastest growing carpinus species preferred for bonsai. The leaves will either be red, yellow or orange in fall. Sometimes, color can vary for leaves on same branch.
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Carpinus Turczaninowii
(Yeddo Hornbeam)
The other Korean Hornbeam. This is a good bonsai candidate because of the small leaves it produce. However, one drawback is it’s slow growing rate. The branch will grow twiggy. It is also known under these various name: Carpinus tschonoskii, Yedoensis hornbeam, Yeddo hornbeam, Carpinus turkzaninowii, Korean hornbeam, Turkish hornbeam.
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Carpinus Bonsai care
Light
The carpinus trees are very forgiving about light conditions. They will grow attractive and open with shaded light. They will however grow very dense in full sun. In spring, young shoots are best protected with partial shade. The rest of the growing season, full sun is preferred.
Watering
It is important not to let the soil dry out in between watering. Moderate watering is needed but in the peak of the summer growing season it will require more and constant watering.
Feeding and Fertilizer
It is not recommended to fertilize for two months after a repoting exercise. In normal growing conditions, half strength home fertilizer is preferred every other week from spring to fall.
Carpinus Bonsai Techniques
As the bark can be delicate, protection is needed to wire branches of hornbeam bonsai trees. Minor pruning are best done in spring right after flowering. The carpinus trees are healing their scars very quickly. Structural and major pruning should be done in later winter. Leaves reduction can be achieved successfully by defoliation but this will inhibit flowering and fruiting.
Carpinus Bonsai pests and diseases
Very few insect will attack hornbeam trees. As for disease, a few fungi will cause leaf spot but nothing very serious. No real treatment in necessary.
Carpinus Bonsai propagation
Seed: It is possible to germinate ironwood bonsai trees from seeds. All the species are easy to germinate. The Carpinus koreana as a very good, see almost perfect germination range. Seeds from carpinus will often need up to year to germinate if not sow immediately after being ripe.
Cuttings: carpinus cuttings are easier to root in early spring from juvenile tree shoot.
