More than 400 varieties of Japanese Maple trees exist today, giving gardeners plenty of choices for their gardens. Grown for their beautifully-shaped leaves, unusual twisting trunks and gorgeous fall color, the trees also come in weeping forms and upright types. Given the proper care, these slow to moderate growers can add to a garden or landscape for years to come.
Planting and Fertilizing
Japanese maple trees thrive in USDA hardiness zones 6 to 9 as long as they get planted in acidic soil that's well-drained. To create acidic soil, gardeners can add acidic planting mix to the soil that's added back into the planting hole. Planting the tree on a mound also helps move water away from the trunk to avoid disease. The trees also prefer morning sun and afternoon shade. One of the best ways to give these trees the shade they want is to plant them under other, taller trees that provide filtered light or full shade.
Watering and Mulching
These trees require moist conditions. If the top 3 or 4 inches of soil feels dry, soak the area around the tree until it's moist 12 to 18 inches deep. Otherwise, if the top few inches feel moist, avoid watering the tree, as this can lead to fungus disease. Adding a 2 to 3-inch layer of mulch around the base of the tree also helps retain moisture. The mulch should be placed at least 3 inches away from the trunk of the tree.
Avoiding Leaf Burn
During hot, windy summer days, the leaves of the Japanese maple dry out more quickly than the roots can provide water, causing the leaves to turn brown on the edges. Leaf burn may also be caused by too much water, too much fertilizer or an underdeveloped root system, especially in newly planted trees. Eventually, the burnt leaves fall off the tree, but the tree will put out a second set of leaves eventually. Watering the tree if the soil feels dry, or not watering the tree if the soil seems too wet eventually reverses these problems. Since the tree is stressed, no more fertilizer should be applied until the tree looks healthy again.
Pests and Diseases
Some trees get attacked by aphids or caterpillars. If the attack is bad enough, a pesticide may be used on the tree. Maples also get attacked by a fungus disease called verticillium wilt that eventually kills entire branches of the tree. Since the fungus grows in the soil around the tree, one way to avoid the problem is to not water the trunk of the tree.
Japanese maple trees require little pruning. If light pruning is required to make the tree's form look better, late summer or early fall remains the best time to do so. This involves carefully looking at the tree from all angles, then deciding what branches need to be pruned to maintain the tree's natural shape. This is also a good time to clean out small twigs growing along the trunk, branches rubbing against each other, and dead wood.