Bonsai is the art of keeping miniature trees in small flat pots and styling them to resemble the look and feel of older, more weathered trees. Japanese maples can make excellent specimen bonsai trees. With proper care, pruning, wiring and feeding, keeping a Japanese maple as a bonsai is not difficult.
Japanese maples require a period of dormancy, even when grown as a bonsai. In general, around 1,000 hours of temperatures below 40 degrees Farenheit are required each winter for proper dormancy. Without this period of dormancy, Japanese maples will grow well and then suddenly go dormant after around two years. In many cases, if this dormancy happens at the wrong time of year, the tree will die. Be careful, though. Japanese maples won't tolerate temperatures below 30 degrees Farenheit and can be very sensitive to root freezing. If you are going to grow Japanese maples as bonsai, you will likely need a cold frame in colder climates.
Water your Japanese maple bonsai daily during the growing season. Japanese maples require a lot of water. However, be sure to use a well draining bonsai soil to prevent root rot. Keep your bonsai on a humidity tray if you live in a dry climate. A humidity tray is a ceramic tray filled with gravel. Excess water that drains from the pot spreads through the gravel in the tray and evaporates, creating an envelope of higher humidity around the tree.
Fertilize your Japanese maple bonsai with a dilute fish emulsion solution. Use 1/4 strength emulsion twice a week on your trees during the growing season. If you want to fertilize less often, use a 1/2 strength fish emulsion once a week. Remove leaves as they drop off to ensure a healthier tree.
Wire your tree to create both formal and informal styles. To wire your branches, wrap them with aluminum or copper wire at a 45 degree angle to the branch. Gently bend the branch to the desired position. Listen carefully for sounds of cracking or breaking and stop immediately if you hear them. If your wire isn't strong enough to hold the branch in place, wrap a second or third piece of wire next to the first.
Prune your tree in fall or winter after leaf fall. Trees pruned in the spring and summer often "bleed" too much. Prune your tree by working from the bottom up and the inside out until you create the particular shape you desire. Prune using sharp bonsai pruning shears or sharp, stout scissors.