The endless allure of the Japanese maple

The Japanese maple has no flowers to speak of. It is not a reservoir of life for native pollinators. It is somewhat expensive to buy and is slow to grow. Every garden should have one.

Few other trees or shrubs create such an aura of grace and serenity in the landscape, especially when placed with care and groomed artfully.

Set aside its inconspicuous red blossoms of early spring, and you find ornament in every season. In April, the first flush of growth is often tinged with rich tones of reds and chartreuse. In summer its leaf forms add cool chic to the heat. In autumn, the maples are ablaze in color. The winter maple is a piece of sculpture, particularly the weeping forms.

But it is in the next few weeks that the Japanese maple is its most strikingly handsome, when the leaves turn scarlet, orange or golden, or a combination of all three, depending on the variety. In its native land, this natural spectacle induces its own ritual of leaf viewing, momijigari.

One of the challenges with such a sterling plant is that its appeal and genetic variability have led to the introduction of thousands of varieties. It is tough to single out one, which is why gardeners with a little room tend to become smitten and find places for a little collection.

The Japanese maple is a term that encompasses varieties of several species, mostly Acer palmatum, but for the home gardener it is more useful to sort this cast of players into size and shape, and thus the maple's use in the landscape.

Maple connoisseurs classify these acers into arcane subgroups based on growth habit and leaf shape, but for most of us the Japanese maple can be reduced to three classes: pendulous, mounded specimens; ornamental trees that might reach 20 feet or more; and the in-between maple world of upright large shrubs or small trees. It is the last category that is the least employed and of most value in today's smaller gardens.

Beyond this basic architecture, there are two other traits that the buyer has to consider: the leaf form and the leaf color. Typically, Asian maple varieties have leaves with three to nine lobes; some are stubby, others so fine as to be threadlike. Even the coarser-leafed varieties read as fine-textured plants, certainly in comparison with native maples or the Norway maple, the last a dense and invasive tree to be avoided at all costs.

Leaf form may be the province of the dilettante, but color is not: It's a primary consideration. There are many red- or purple-leafed varieties; they are beautiful but overused and lose vibrancy of color in hot, humid climates. I'm with Elizabeth Mundy of Acer Acres in Beaverdam, Va., who says that we should plant more green-leafed varieties. Their acid-green tones in early spring capture the frisson of the season, but most of all, they produce the best autumn colors, including different shades of red.

"I think the greens are very underused," said Mundy, whose wholesale nursery grows 400 varieties for garden centers. The greens also show better against dark backdrops or red-brick walls, she said.

Japanese maples should be located with care so that both the plant and its keeper are happy. At the garden center, the young weeping varieties in particular offer little clue to their eventual habit or size.

The most effective weeping maples are treated as a piece of sculpture and framed either by structures or other plantings that announce their importance.

Weeping maples don't grow that tall, but they grow wide. A common mistake is to place them next to a wall or a path, Mundy said. You should give a weeping variety at least three feet on each side. After 40 or 50 years, they'll need more: At the National Arboretum's Gotelli Dwarf and Slow-Growing Conifer Collection, you will find a specimen named Ornatum that is 12 feet high and 18 feet across, and one named Tamukeyama that is 13 feet high and 20 feet across. These are extreme beauties, but you get the idea.

An upright variety, given pride of place, functions as a specimen. Planted this way, maples are especially effective when seen from indoors. You can accentuate them by uplighting them.

In the right setting, a mass planting is sublime. At the Japanese ambassador's residence in Washington, a grove of approximately 20 upright Acer palmatums have been placed on an island across from the Tea House. They have been pruned to reveal their gray, striped bark, and rise from a bed of moss. Such a "forest" oozes Zen sophistication.

Japanese maples grow well in full sun, but in a hot, humid climate they are happier in partial or dappled afternoon shade (not deep shade). These maples like some moisture, especially if it turns dry in the heat of summer, but should not be overwatered. They grow well in organically enriched soil. Drainage is essential.

A late frost in early spring can damage the new growth, so the gardener should keep an eye on the weather and cover plants if necessary.

Maples should be shaped after they have become established, in the second or third year after planting. Deft pruning improves the character of upright maples and is essential for weeping forms, whose power comes from their studied asymmetry and development of trunk architecture. Neglected plants become congested, which blurs the optimum form. Overgrown plants can be brought back to a sculptural specimen over the course of two or three years. You should not remove more than a quarter of the vegetation at one go, and preferably less. Leave some foliage above the uppermost branches to shield the bark from the sun. Don't let branches sweep the ground, but do not shape the foliage into a mop.

Some gardeners like to prune their maples in winter, when they have the clearest view of the branch structure. Others worry about the effects of bleeding then and like to prune in the early fall, after the leaves have done their work for the year.

Smaller varieties of both weeping and upright forms grow happily in containers, making these acers available to those with small urban gardens. They need more care - attentive watering in summer, for example - and deserve handsome planters that declare that this is where they live. The planters should be frost-proof with drainage holes, and the soil should be open and free-draining. In a container ample enough, the maple will go several years before needing to be repotted and root pruned.

Choose your variety

There are so many varieties that the choice has to come down to intended placement and thus growth habit, and then personal choice. But here are some commended by maple grower Mundy; Deanna Curtis, curator of woody plants at the New York Botanical Garden; landscape designer Barbara Katz, of Bethesda, Md.; and myself.

Mounded, weeping forms:

• Green Mist is a cut above the standard Viridis among green, cut-leaf weepers and finishes the season with an orange blaze of color.

• Germaine's Gyration is a larger mounded variety, with orange-red foliage in the fall.

• Among red weeping maples, Inaba Shidare is considered choice for the showiness of cut leaves, and Orangeola has orange tones in the spring and goes out with a bang with intense orange-red fall color. Pink Filigree has highly dissected leaves that are rose-pink in the spring, purple in the summer and orange-red in the fall.

Upright forms - trees

• Bloodgood is the stalwart purple-leafed tree, growing to 25 feet or more at maturity. If it has a fault, other than its commonness, it doesn't have the lightness of more open forms.

• Emperor I is considered an improved alternative, holding its color well in shade.

• Osakazuki is similar in outline and color (bright green) to the species tree but valued for its rich crimson fall color.

• Sango kaku, the coral-bark maple, is more vase-shaped and grown for its rose-red stems in winter, though it gets larger than most people account for, and it's stiffer in habit than others.

• Kihachijo has prominent serrations to the leaf lobes and turns golden-yellow tinged with reds in the fall.

Upright forms - small trees or large shrubs:

• Hubb's Red Willow grows to 12 feet or so and is narrow and vase-shaped, so it can be placed in tight quarters. The green leaves are threaded, and the seeds, or samara, are conspicuously scarlet.

• Matsuyoi forms a small tree with unusual drooping and feathery leaves that turn orange in the fall.

• Japanese Sunrise is a smaller upright with red coloration to new growth and bright green leaves that turn a blazing gold in fall.

• Hogyoku grows as a patio tree with rich, broad-lobed green leaves in season turning to a pumpkin-orange in November.

• Shiraname grows as a large shrub with spring foliage that starts out red before turning green. Its fall color is bright yellow.

• Tsuma gaki forms a round shrub, eventually 10 feet high and wide, and is valued for its spring colors of butter-yellow with red margins. It turns deep green in summer with crimson autumn leaves.