Growing Japanese Maples
Japanese maples may not grow fast — but these graceful, ornamental trees with airy foliage are worth the wait.
Native to Japan and Korea, Japanese maples (Acer palmatum) are deciduous trees, sometimes grown as small shrubs, that top out around 20 feet high. They typically produce many layers of branches that grow horizontally, although they can also grow upright or develop spreading or weeping forms.
Most are hardy in zones 6 to 8, although cold climate gardeners can find varieties rated for zone 5. Green leaf varieties are usually easier to grow in hot, arid regions.
Their colors make Japanese maples stand out. Many put out new growth each spring that practically glows red when backlit by the sun; by summer, those leaves become green, and in autumn, they turn scarlet, gold and orange.
Other leaf colors include plum, bronze, purple, yellow, pink or vivid red. With over 700 cultivars, you’ll find a wide variety of leaf shapes and textures, too.
While Japanese maples are excellent as specimen trees or understory trees grown with azaleas, camellias and other shade-loving plants in woodland settings, they’re also fine for planting alongside driveways, walls, and fences.
Gardeners with limited space can plant dwarf varieties or grow the trees in containers to move around for portable color. Some varieties are easily pruned into bonsai plants.
Site your Japanese maple in a spot that gets dappled shade or filtered sun. Some cultivars can take full morning sun, but read the tag before you buy.
Too much afternoon sunlight can burn the edges of leaves. Curled or dried out leaf tips are also signs of too much sun, but lightly burned trees will usually recover. If you need to move your tree, wait until fall to lessen the chance of transplant shock.
Autumn is also the best time to plant. Choose a spot with protection from strong winds and late spring frosts. (If frost hits your new tree after it’s started to leaf out, you may want to cover it to protect it.)
Dig a hole three times the width of the root ball, but not as deep. When you put the tree into the hole, it should sit slightly above the soil line. Mix some slow-release fertilizer into the hole, backfill and water thoroughly.
While Japanese maples will grow in most soils, they prefer slightly acidic soil. Avoid planting them in highly alkaline or salty soils. Use a good planting mix for a container.
Japanese maples need soil that drains easily, but they like consistent moisture. Water regularly if rainfall is scarce, especially during the first 3 years of growth, and mulch to help keep moisture in the soil.
These handsome trees seldom need much pruning, but remove dead or diseased wood and crossed branches when you see them. If you want a Japanese maple with a single trunk, remove the extra stems while it’s young.
Pests that attack Japanese maples include Japanese beetles, mites, scale, aphids and mealybugs. Dislodge them with a strong stream of water from your hose. If they keep coming back, step up to a pesticide that targets your specific problem. follow product directions.
Canker and verticillium wilt are incurable fungal diseases that can harm Japanese maples. Help prevent them by keeping your tree healthy and watering and fertilizing as needed. Also be careful not to injure the bark by hitting it with a lawn mower or other garden equipment.
Another disease, anthracnose, shows up as black spots on distorted or dying leaves. It often occurs in wet, humid weather, and there’s no chemical cure. But you can help prevent this disease, too, by keeping your garden cleared of dead or diseased plant parts and by using only clean, fresh mulch. The good news is that many diseases resolve themselves, so your Japanese maple can recover and grow for many years to come.