There are many maple species in Japan, but most of the trees that gardeners call Japanese maples are varieties of Acer palmatum, with some belonging to A. japonicum and A. shirasawanum. The natural range of A. palmatum includes not only Japan but parts of Korea, China, and Russia. The species can grow to 20 or 30 feet tall, often in the understory of open woods between larger trees. But it has been cultivated in Japanese gardens for centuries. Gardeners have taken advantage of the plant's natural genetic variation to select hundreds of distinct cultivars. "The range of leaf shape is pretty phenomenal," says Ben Chu, horticultural supervisor at Seiwa-En, the Japanese garden at the Missouri Botanical Garden in St. Louis.
Japanese maples are at their best in USDA Plant Hardiness Zones 6 through 8; a few are hardy as far north as Zone 4b. They do especially well in the moderate conditions of the Pacific Northwest. For colder climates, some types will grow in containers that can be moved to shelter in winter. In hotter areas, trees need consistent water and afternoon shade to thrive.
Plant a Japanese maple in early spring or before midautumn, but not in summer. Planting in early fall gives the tree time to put down new roots so that in spring, when the sap begins to rise, the tree can put energy into developing topgrowth. Water deeply at least once a week until the ground freezes. Japanese maples require consistent moisture, but an established tree is not likely to need fertilizing. They tolerate a wide range of soil pH, though slightly acidic soil is ideal. The one nonnegotiable requirement is good drainage. Especially in clay soil, it's wise to dig mulch or composted bark into a wide area that extends beyond the planting site. Then dig a wide planting hole that is no deeper than the root ball. If perennials or a groundcover will be planted beneath the tree, Chu advises planting them at the same time as the tree, in the soil beyond the root ball. That way, after the tree has reached out with its fibrous roots, the roots won't be disturbed by digging.
Many of the smaller Japanese maple varieties can be grown in containers. In fact, Don Mahoney, curator of plant collections at the San Francisco Botanical Garden in Golden Gate Park, figures he has 30 different varieties planted in pots in his confined city back yard.
He moves them into as much sun as he can in spring to help them develop their pigment; in the arid summertime, he moves them into the shade. "Fall color is very unusual on the West Coast," he says, "so after the hot spell, I move them out front and center where I can admire them."
One of Japanese maples' chief attractions is their vivid fall color, but many kinds have colorful leaves throughout the season, and sometimes leaves that change, chameleon-like, from spring through autumn. Another useful attribute is that, though full sun is best, most Japanese maples can tolerate some shade—not deep shade, but the kind of dappled sunlight that finds its way between buildings and trees into city gardens.
Some cultivars are as tall as the forest species. Others are tidy little mounded shrubs. They may be upright and vase-shaped or have horizontal or cascading branches. Some have a deep red tint to their leaves; others have foliage that is bright green, creamy white, yellow, pink, or orange. Nearly all are spectacular in fall.
Every Japanese maple has leaves with five to seven pointed lobes. In some varieties, however, the lobes are much more slender, often edged with teeth, giving the foliage an overall lacy effect—leading them to be called laceleaf maples or, with finer leaves, threadleaf maples. Usually, those plants have a mounded or cascading form.
In Zone 5, late frosts may frazzle the tips of early leaves. Verticillium wilt, a fungal disease spread through the soil or grafts, is sometimes a problem, especially if the tree is stressed by underwatering, overwatering, or too much sun or fertilizer. Failing branches should be pruned out immediately and the tree given the conditions it needs to stay healthy. If a tree is severely afflicted, it's time to give up on it. But the biggest vulnerabilities of Japanese maples, especially to the laceleaf and threadleaf types, are sun scald or drying out in hot winds. So whether in containers or in the ground, shelter these maples from the prevailing wind.
Because of their distinctive beauty, Japanese maples are usually planted as attention-grabbing specimens. In the traditional design of the Anderson Japanese Gardens in Rockford, Illinois, the summer garden is blanketed in green and relies on punctuation by maples with colorful foliage such as Acer palmatum 'Crimson Queen,' 'Garnet', and 'Bloodgood' in key focal points, notes curator Tim Gruner.
Japanese maples lend themselves to subtler effects, as well: Cascading types are a favorite of Andrew Bunting, curator of the Scott Arboretum at Swarthmore College in Swarthmore, Pennsylvania, who likes to see them draped gracefully over the top of a wall.
Dallas landscape architect David Rolston uses Japanese maples in his designs for texture and contrast. "Any time you can use something soft in a hot climate, it is welcome," he says. Texas is outside the maples' comfort zone, so it is crucial to provide afternoon shade and regular water.
A Japanese maple may be the high point of a garden's design, but be sure to choose and site the plant with an eye to its needs. Don't plant the maple too close to a house or walk, where it will require major pruning or where people may trample on its root zone. It is better to buy a cultivar that won't outgrow its space than fight to keep a too-large plant in bounds. Fortunately, the wide range of Japanese maples means that there is the right plant for any spot.
Jon Carlson of J. Carlson Growers in Rockford, Illinois, which specializes in Japanese maples, questions customers closely about their growing conditions and is careful about recommending finicky cultivars. "We don't sell them to anybody that wants to buy them," he says. "It's like helping a puppy find a good home."
Japanese maples can often be found at home centers for $50 or $75 in spring, but it is key to investigate the cultivar's needs and ultimate size before buying. A too-big or too-delicate tree is no bargain.
In the leafy suburbs of Chicago, many front yards feature Japanese maples whose purple leaves shine like rubies when they catch the sun in spring. But even in deep shade, green-leafed types manage to make a statement. Between tall shade trees, upright maples grow 15 or 20 feet high and glow like torches in fall. They are as attractive in a grand, sweeping garden as they are behind a city town house. Removed from the forests of Asia, Japanese maples look at home in almost any yard.
Learn how to prune a Japanese maple.
There are hundreds of named cultivars; these are some of the most dependable.
Cascading, almost prostrate tree has lacy green leaves. Orange to crimson fall color. Stake when young to desired height. Relatively hardy. Zones 5-9
All-around utility player, widely available and favored by landscapers. Upright tree, to 15 feet tall, has deep purple leaves, turning crimson in fall. Palmate (relatively wide-lobed) leaves and horizontal branching. Winter-hardy and heat-tolerant.
Compact, rounded plant, 6 to 10 feet tall, with finely cut purple leaves, turning red in fall.
This weeping, mound-forming plant, to 8 feet, is fine and ferny. Its purple-red foliage turns greener in summer, then orange in fall. Twisted, contorted branching.
Upright tree, to 15 feet, has purple palmate leaves turning crimson in fall. Leafs out late to avoid spring frosts. Sun scorch– resistant.
Upright tree, to 20 feet, with striking coral red bark on first-and second-year stems. Palmate leaves are red-tinged in spring, green in summer, and gold touched with red in fall.
Vase-shaped tree, to 15 to 20 feet, with medium green summer foliage, turning red in fall. Known as the only upright laceleaf maple.
Learn how to prune a Japanese maple.