How to Manage and ID Japanese Maple

Introduction: Japanese maple is one of the most versatile trees for any yard, patio or garden. Often grown for its unique 7-palmed green or red colored leaf, the maple also has an interesting growth habit with a fine leaf texture and muscular-looking multiple trunks. Japanese maples have extraordinary fall colors that range from bright yellow through orange and red, and is often striking, even on trees grown in total shade.

Specifics: Scientific name: Acer palmatum
Pronunciation: AY-ser pal-MAY-tum
Common name(s): Japanese Maple
Family: Aceraceae
USDA hardiness zones: USDA hardiness zones: 5B through 8
Origin: not native to North America
Uses: Bonsai; container or above-ground planter; near a deck or patio; trainable as a standard; specimen
Availability: generally available in many areas within its hardiness range.

Cultivars: There are many cultivars of Japanese maple with a wide variety of leaf shapes and color, growth habits, and sizes: ‘Atropurpureum’ - reddish leaves with five lobes; ‘Bloodgood’ - new foliage bright red, darkening to dark green; ‘Burgundy Lace’ - reddish foliage and cut leaves; ‘Dissectum’ - finely dissected leaves in green or red, 10 to 12 feet tall; ‘Elegans’ - leaves with rose-colored margins when they first unfold; ‘Ornatum’ - foliage is cut and reddish.

Pests: Aphids can infest Japanese maples and heavy populations can cause leaf drop or a dripping of "honeydew". Scales can be a problem. Neither insect causes death. If borers become active, it probably means you have an already sick tree. Keep the tree healthy.
Scorching may be a problem during periods of high temperatures accompanied by wind. Planting Japanese maple in a bit of shade can help. Keep trees well watered during dry periods. Symptoms are tan dead areas on foliage.

Description: Height: 15 to 25 feet
Spread: 15 to 25 feet
Crown uniformity: symmetrical canopy with a regular (or smooth) outline, and individuals have more or less identical crown forms
Crown shape: round; vase shape
Crown density: moderate
Growth rate: slow
Texture: medium

Trunk and Branches: Trunk/bark/branches: bark is thin and easily damaged from mechanical impact; droop as the tree grows, and will require pruning for vehicular or pedestrian clearance beneath the canopy; routinely grown with, or trainable to be grown with, multiple trunks; showy trunk; no thorns
Pruning requirement: requires pruning to develop strong structure
Breakage: resistant
Current year twig color: green; reddish
Current year twig thickness: thin

Foliage: Leaf arrangement: opposite/subopposite
Leaf type: simple
Leaf margin: lobed; serrate
Leaf shape: star-shaped
Leaf venation: palmate
Leaf type and persistence: deciduous
Leaf blade length: 2 to 4 inches
Leaf color: green
Fall color: copper; orange; red; yellow
Fall characteristic: showy

Pruning: Most maples, if in good health and free to grow, need very little pruning. Only "train" for developing a leading (or multiple) shoot(s) which will eventually establish the tree's framework.
Maples should not be pruned in spring and could bleed profusely. Wait to prune until late summer to early autumn and only on a young tree. A habit should be encourage in which the branches develop low and grow up at sharp angles. If suckering of green-leafed root stock occurs below the graft line on your red-leafed grafted variety, remove the green sprout immediately.

Culture: Light requirement: tree grows in part shade/part sun; tree grows in the shade
Soil tolerances: clay; loam; sand; slightly alkaline; acidic; well-drained
Drought tolerance: moderate
Aerosol salt tolerance: none
Soil salt tolerance: moderate

In Depth: The growing habit of a Japanese maple varies widely depending on cultivar. From globose, branching to the ground to upright to vase-shaped, the maple is always a delight to look at. The globose selections look best when they are allowed to branch to the ground. Be sure to clear all turf away from beneath the branches of these low growing types so the lawn mower will not damage the tree. The more upright selections make nice patio or small shade trees for residential lots, and, with pruning to remove drooping branches, provide adequate clearance for pedestrian traffic to pass close to the tree. More compact cultivars make wonderful accents for any landscape.
Japanese maple tends to leaf out early, so it may be injured by spring frosts. Protect them from drying winds and direct sun by providing exposure to partial or filtered shade and well-drained, acid soil with plenty of organic matter, particularly in the southern part of its range. Leaves often scorch in hot summer weather in USDA hardiness zones 7b and 8, unless they are in some shade or irrigated during dry weather. More direct sun can be tolerated in the northern part of the range. Be sure drainage is maintained and never allow water to stand around the roots. The tree grows fine on clay soils as long as the ground is sloped so water does not accumulate in the soil. Responds well to several inches of mulch placed beneath the canopy.