Japanese maples are a popular tree because of it graceful growing habit. It’s no wonder why so many people are drawn to them. They are a hardy dwarf tree which has been used in many landscapes due to their beautiful color and texture. They stun the viewer with a wide array of leaf colors and shapes, not to mention colorful wood of the trunk and branches. Their ability to adapt to small containers make them a wonderful choice for bonsai.
The natural growth habit of japanese maples vary by variety and include upright and spreading forms.
Upright forms tend to reach the size of a medium height tree at 30 – 40 feet, while spreading forms may only reach 10 feet. Most are fast growing, sending out a strong surge of growth of 8-18” in the spring right after dormancy.
Japanese maples prefer full sun but many adapt equally well in an area of dappled sunlight and those grown in containers seem to prefer the break of intense sun over the summer. The lack of proper sunlight is seen by poor color within the foliage and reduced vigor in its growth.
Hardiness of Japanese maples range from temperature zone 4 (-25 degrees) to zone 6 (-10 degrees) but those grown in container form would all require extra protection from the cold.
When one thinks of Japanese Maples, many think of the color red. Actually the colors can range from red to green with every variation in between. It’s difficult to think that a tree can have so many differences but this is my attempt to explain a few of them.
Acer Palmatum “Bloodgood” is an upright tree form Japanese Maple with good red color. I consider it fast growing and one of the hardiest. Each leaf has six lobes and measure apx. 3 – 4 inches across.
Some other varieties in the Palmatum family include “Burgundylace”, “Arakawa” (known for its rough bark), “Katsura” and “Butterfly”.
The red cut leaf is probably the most popular form of Japanese maple. This would include the varieties of Acer Dissectum “Red Select”, “Red Feathers”, and “Ever Red”.
Each leaf measures apx. 3 inches across. Acer Dissectum. “Seiryu” is a true winner for anyone wanting a true cutleaf upright maple which is green.
While these are popular choices for their known color, there still remains a group of others which host there own eye pleasing attributes.
Maples can be grown in any of the bonsai styles, but one of the best reasons for using Japanese maples in bonsai is their aggressive growth habit. Maples are nearly indestructible as long as you provide them with basic care.
Maples are hardy trees and are required to be grown outdoors (don’t attempt to grow them indoors) where they will have abundant circulation and light. Over the spring maples grow rapidly before slowing down during the summer. Trees struck by autumn frost can give viewers a second show as many are know to produce outstanding autumn foliage color.
Japanese maples need to be over-wintered in a protected area where overnight temperatures stay above 24 degrees F. Keep the soil evenly moist even though it is dormant. The tree will not need light when it does not have leaves, but light should be provided as soon as the buds open.
When repotting or creating your own bonsai, transplanting is better done in the spring while the trees are still dormant and leaves are still in the bud stage. The roots of healthy trees can be cut back quite hard which makes it easy to get them into smaller containers. Just remember that using a smaller container will require that you water more often.
Using a medium fast draining soil is good but keeping them watered in the summer can be a challenge. Trees which are allowed to dry too hard will cause leaves to burn leaving a lasting mark for the remainder of the year. Placing trees in a location so they are in and out of sun throughout the day helps trees stay hydrated and keeps containers from getting too hot, which could damage the roots.
Japanese maples back-bud readily on old wood and heal well from hard cutting, although it takes time for the bark to fully roll over the cut.
They do not form much taper in bonsai culture unless they are routinely cut back. New branches can be “thread-grafted” in order to get a branch to grow exactly where you want it.
The new growth on japanese maples when left untouched is long and out of proportion for small bonsai.
Where to cut and when you should cut the new growth depends on your goals.
If your goal is to develop thicker branches it is best not to cut back the new growth, however unsightly it may be. This will lead to thicker branches in the shortest amount of time. Generally thick or heavy branches are wanted on the bottom of a tree. In this case, allowing the branch to grown untouched by cutting is required to thicken to the desired size. The opposite holds true for keeping branches small. The time when you are allowing the branches to thicken is also the time to shape branches with wiring.
Once the branches have reached close to the desired thickness they can be cut back to two or more leaves. The branch will die back to the nearest bud so leave room for this to happen and cut back the dead wood once the new branch has started growing from the bud.
This should be done when the new growth has begun to harden, usually in late spring to early summer.
Pinch back to the point of two or three leaves once the new growth extends beyond that point. Pruning to refine branches is best done in mid-spring when enough time is left in the growing season for a second serge of growth to develop.
Japanese maple bonsai can be trained with wire.
The wood is brittle so care should be taken when bending them. Also keep in mind that the bark is smooth and can be scarred if the wire is left on too long, so be diligent. Shallow scars may disappear as the tree grows but deep scars may be permanent.
Full to partial sun exposure while in leaf. It is better to place trees in full sun during the spring and move to a partial exposure during the summer as the leaves are delicate and prone to scorching. Bright light is necessary for best color in non-green varieties. If a colored leaf is not given enough light the leaves will turn green temporarily. This condition will not hurt the plant (assuming there is enough light to continue photosynthesis) but may be undesirable cosmetically. Plants should be paced in light as soon as the buds break to avoid scorching the leaves.
When actively growing feed with a general purpose fertilizer every 2nd or 3rd week at half strength.
Feed monthly at half strength.
(September – October) Use no nitrogen or low nitrogen fertilizers.
Young trees can be started by seed, which can be fun and educational. They are easy to germinate, as anyone with a japanese maple in their landscape will be able to tell about the many seedlings in their planting beds and lawns. However, hybrids such as those stated earlier are generally done by graft or cutting in order to ensure that they are propagated true to variety.
Most of the japanese maples found in garden centers are produced by grafting. This means that one variety is grown on the roots of another, resulting in a faster growing root system than left to grown on its own root system. This is particularly true of variegated varieties, where the light portion of the leaves is slow to photosynthesize. While this is helpful in a landscape environment, the results can be a bulge at the graft (the rootstock may grow faster than the top growth) and not desirable for bonsai. Luckily there are alternative methods.
Japanese maples can be propagated by cuttings. This is an easy method of acquiring more plants that are genetically identical to the parent plant, and thus shares the same characteristics and traits. Regular bonsai soil can be used using a rooting hormone on small portions of second-year growth and the results will be the cultivar you want without a graft line.
The downside to this method is the number of losses and that is that you must wait for the cutting to develop before it will be usable for bonsai.
Air layering is possibly the best method of propagation for japanese maples in bonsai. It is a fairly quick method, highly reliable, and you can end up with a thick trunk on its own roots in months. Japanese maples can be air-layered at any time of the year, although keep in mind that the roots will only form in the spring or fall.
Japanese maples are affected by a few pests, including insects and mammals. Aphids and scale will drain the energy from the branches and japanese beetles may attack the leaves. A healthy tree should be able to defend against a mild to moderate attack, and there are controls available for a severe outbreak.
In addition to insects, deer and mice should be considered. Why this may not be a big deal for landscape plants, it can be devastating to a bonsai. Mice may chew the bark in winter storage.
Although these trees are not pest-proof the troubles are infrequent and they should not deter you from using japanese maples for bonsai.