Japanese maples are a whole field (or forest) of horticulture in themselves. Encompassing thousands of cultivars, this enchanting tribe of small trees is the stuff of which lifelong horticultural obsessions are made.
Japanese Maple History
At the center of it all is the Acer palmatum, the infinitely varied East Asian species that goes by the common name Japanese maple (even though it also occurs in South Korea). Over the centuries, East Asian plant fanciers have brought its diversity into cultivation, selecting and propagating specimens for their unique form, foliage, size, and other characteristics. European and American horticulturists followed suit after Japanese maple made its way to the West in the nineteenth century.
Japanese Maple Groups
Japanese maple cultivars come in several types or “groups”, defined by the shape of their leaves. The Palmatum and Dissectum groups are arguably the most important of these groups, although many popular Japanese maples belong to other sub-tribes.
Palmatum Group
Japanese maples in the Palmatum Group bear standard-issue, hand-shaped leaves with 5 to 7 (or occasionally 9) pointed lobes. Members of this group include:
‘Bloodgood’, a vase-shaped, 20-foot cultivar with deep-purple-red foliage that holds its color through summer until incandescing brilliant red in fall.
‘Hogyoku’, whose relatively shallow-lobed leaves – borne on a rather shrubby, 15-foot canopy – go deep orange in fall.
‘Lutescens’, named for the spring and autumn hues of its large, seven-lobed leaves, which flush yellow-green, mature to light green in summer, and turn bright gold before dropping in fall. It slowly forms a 15-foot, round-crowned specimen.
‘Okagami’, distinguished by its shiny black-purple spring foliage that fades to bronze-green in summer and glows crimson-red in fall. This small tree has a vase-shaped habit.
‘Sango-kaku’, dubbed coralbark maple for the crimson coloration of its young branches. They make a stunning contrast to the silver-gray bark of most Acer palmatum forms. Coralbark maple gradually matures into a multi-trunked, shrubby tree, to 15 feet tall.
Popular cultivars from other Acer palmatum groups include shrubby, 10-foot ‘Butterfly’, with gray-green, white-bordered leaves; ‘Shishigashira’, widely grown for its condensed clusters of crinkly leaves on stubby branches; and ‘Scolopendrifolium’, whose leaves are divided into five long, grassy lobes.
Dissectum Group
The leaves of Dissectum Group cultivars have five to nine deep lobes that are themselves dissected, making for a lacy, shimmering effect. The effect is accentuated by the low, cascading habit of most members of the group. Some of the better varieties from which to choose are:
‘Garnet’, an ornate variety with arching branches that slowly form a dense 9-foot mound. Its leaves flush burgundy-red in spring, fade to red-green in summer and intensify to red again in fall. ‘Ornatum’, is similar to ‘Garnet’ but goes greener in summer and oranger in fall.
‘Spring Delight’, has pale-green, pink-edged new leaves, yet another variation on the Dissectum theme. They evolve to pure viridescent green in summer and golden-orange in fall. This recent introduction develops into a 9-foot-wide, 12-foot-wide mound of pendulous branches.
Other Japanese Maples
There’s more to Japanese maples than Acer palmatum, however – most notably its close relative Acer japonicum. Perversely, the latter goes by the common name full moon maple, even though its botanical moniker literally translates to “Japanese maple”. The elegant, lacy, fingered leaves of Acer japonicum ‘Aconitifolium’ rival those of the finest Acer palmatum Dissectum Group cultivars, especially in fall when they assume a range of smoldering red and orange hues. Slow and shrubby in growth, ‘Aconitifolium’ eventually reaches about 10 feet in height and a bit more in width. It gave rise to the even lacier and shrubbier ‘Green Cascade’, a 5-foot-tall weeper with dainty, deeply cut green leaves and good fall color. Much larger in all its parts is ‘Vitifolium’, which bears expansive, grape-like leaves that flush copper in spring and go ablaze at the end of the growing season.
The nomenclatural confusion continues with golden full moon maple, which actually belongs to a cultivar of a third Japanese maple species, Acer shirasawanum ‘Aureum’. Its yellow new leaves, pale chartreuse summer foliage, and sunset colors in fall can hold their own against Japanese maple, as can its picturesque, compact, horizontally-branched habit. The leaves tend to scorch in the hot sun, so partial shade works best. In contrast, some purple-leaved Japanese maple cultivars show their best in full sun.
Growing Japanese Maple
All Japanese maples thrive in an acidic humus-rich medium. If your garden has sandy or heavy soil, dig a wide planting hole (several times broader than the root ball) and amend and mulch the backfill soil with Fafard® Premium Natural & Organic Compost. Dwarf forms of Japanese maple – including many Dissectum Group cultivars – do well in containers, preferably with a composted-bark-based potting mix such as Fafard® Ultra Outdoor Planting Mix, which is formulated for outdoor containers. They are also traditional candidates for bonsai.
Anyone of these ornate trees will bring elegance and interest to home landscapes and borders. They are best planted as specimens that can be admired by their own laurels.
