The Japanese Maple is a perfect species for bonsai which accounts for it's popularity all over the world. It is adored for it's smaller size, it's lacy leaves, and it's spectacular display of fall colors. It's botanical name is derived from and is descriptive of the tree's leaves, which have at least five lobes and somewhat resemble a human hand. The Acer palmatum includes the red, green, lace-leaf, and thread-leaf varieties. The most popular of these varieties is the red variety.
Watering Your Japanese Maple
Your Japanese maple bonsai will require regular watering from spring, when you begin to see signs that the tree is coming out of dormancy, through late fall when the tree has dropped the last of it's leaves. Japanese maples like moist soil, so you will need to be vigilant in checking the moisture level in the soil to maintain the optimum level of moisture. The best way to water your Japanese Maple is to water it in the morning. Let it dry out over the course of the day but never allow it to become completely dry. You don't want to over-water your Japanese Maple bonsai either. Your bonsai pot should have enough drainage holes to allow all excess water to drain out. Japanese Maple trees are vulnerable to root rot so it is very important that the pots drain thoroughly and the roots don't sit in water.
The Right Amount of Sunlight is Important
Good light conditions ensure smaller leaf size, better back-budding, denser foliage, and stronger fall colors. Avoid burning the sensitive and delicate leaves of your Japanese Maple by providing it with sufficient protection from the intense mid-day sun. Try to place your tree where it will receive direct morning and evening sun, but is protected from the mid-day sun when it is the hottest outside. The sensitive leaves of the maple can actually burn if exposed for long periods to intense sunshine. In the spring and autumn the mid-day sun is relatively mild and so it is OK to leave your bonsai in the full sun all day at these times of the year. Another thing to protect the leaves of your Japanese from is hot, dry summer winds, which can also burn the leaves. Your Japanese Maple will be especially vulnerable to sun and wind burn for a week or more after pruning it's roots and re-potting it. Be sure you keep it out of harsh sun and wind during this time.
Japanese maples, while being hardy, should be placed in an area that is protected from cold and harsh winter winds also. Winter winds tend to be dry winds, and even though your Japanese maple will be in a state of dormancy during the winter, cold drying winds can cause damage.
Humidity
All plants love a humid environment, and your Japanese Maple will thrive in this type of environment. Humidity can be increased by filling a shallow container with small stones, and then covering the stones with water, and then placing your bonsai pot on top of the stones. The humidity level is increased as the water evaporates from the shallow container. Additional humidity slows down the water loss from the trees leaves, a process called transpiration. Another way to increase the humidity level and reduce the transpiration of water from the leaves is to give your bonsai a frequent spraying with a fine mist.
Feeding
Give your Japanese maple bonsai its first feeding in early spring when you first see new growth appearing using a slow-release, high nitrogen fertilizer. Continue feeding every 2-3 weeks until about mid-autumn. Fish emulsion is a good choice as a natural fertilizer. If you're using a chemical fertilizer make sure that you only use a half strength solution. A balanced 20-20-20 fertilizer is recommended. You should stop fertilizing your bonsai tree during the hottest weeks of the summer to avoid any possible damage. Switch to a low nitrogen fertilizer in mid-autumn in oder to help harden off the current year's new growth. this will help prepare the tree for the upcoming winter.
If you have repotted and done some spring root pruning then do not feed during the two months following repotting when a tree is weakened or you could cause root damage.