Fact Sheet ST-23November 1993

Acer palmatum

Figure 1. Middle-aged Japanese Maple.

Japanese Maple 1

Edward F. Gilman and Dennis G. Watson2

INTRODUCTION

Japanese maple has a height and spread of about20 feet, but there are much smaller selections available(Fig. 1). The multiple trunks are muscular-looking,picturesque, grey and show nicely when lit up at night.Japanese maple is grown for its green or red coloredleaves, interesting growth habit and fine leaf texture.Fall color ranges from bright yellow through orangeand red, and is often striking, even on trees grown intotal shade. Growth habit varies widely depending oncultivar from globose, branching to the ground toupright, vase-shaped. The globose selections look bestwhen they are allowed to branch to the ground. Besure to clear all turf away from beneath the branchesof these low growing types so the lawn mower willnot damage the tree. The more upright selectionsmake nice patio or small shade trees for residentiallots, and, with pruning to remove drooping branches,provide adequate clearance for pedestrian traffic topass close to the tree. More compact cultivars makewonderful accents for any landscape.

GENERAL INFORMATION

Scientific name: Acer palmatumPronunciation: AY-ser pal-MAY-tumCommon name(s): Japanese MapleFamily: AceraceaeUSDA hardiness zones: 5B through 8 (Fig. 2)Origin: not native to North AmericaUses: Bonsai; container or above-ground planter; neara deck or patio; trainable as a standard; specimenAvailability: generally available in many areas withinits hardiness range

DESCRIPTION

Height: 15 to 25 feetSpread: 15 to 25 feetCrown uniformity: symmetrical canopy with aregular (or smooth) outline, and individuals have moreor less identical crown formsCrown shape: round; vase shapeCrown density: moderateGrowth rate: slowTexture: medium

Foliage

Leaf arrangement: opposite/subopposite (Fig. 3)Leaf type: simpleLeaf margin: lobed; serrate

1. This document is adapted from Fact Sheet ST-23, a series of the Environmental Horticulture Department, Florida Cooperative Extension Service,Institute of Food and Agricultural Sciences, University of Florida. Publication date: November 1993.

2. Edward F. Gilman, associate professor, Environmental Horticulture Department; Dennis G. Watson, associate professor, Agricultural EngineeringDepartment, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville FL 32611.

Acer palmatum -- Japanese Maple Page 2

Leaf shape: star-shaped

Figure 2. Shaded area represents potential planting range.

Leaf venation: palmateLeaf type and persistence: deciduousLeaf blade length: 2 to 4 inchesLeaf color: greenFall color: copper; orange; red; yellowFall characteristic: showy

Flower

Flower color: redFlower characteristics: inconspicuous and notshowy; spring flowering

Fruit

Fruit shape: elongatedFruit length: .5 to 1 inchFruit covering: dry or hardFruit color: redFruit characteristics: does not attract wildlife;inconspicuous and not showy; no significant litterproblem

Trunk and Branches

Trunk/bark/branches: bark is thin and easilydamaged from mechanical impact; droop as the treegrows, and will require pruning for vehicular orpedestrian clearance beneath the canopy; routinelygrown with, or trainable to be grown with, multipletrunks; showy trunk; no thornsPruning requirement: requires pruning to developstrong structureBreakage: resistantCurrent year twig color: green; reddishCurrent year twig thickness: thin

Culture

Light requirement: tree grows in part shade/part sun;tree grows in the shadeSoil tolerances: clay; loam; sand; slightly alkaline;acidic; well-drainedDrought tolerance: moderateAerosol salt tolerance: noneSoil salt tolerance: moderate

Acer palmatum -- Japanese Maple Page 3

Other

Figure 3. Foliage of Japanese Maple.

Roots: surface roots are usually not a problemWinter interest: tree has winter interest due tounusual form, nice persistent fruits, showy wintertrunk, or winter flowersOutstanding tree: not particularly outstandingInvasive potential: little, if any, potential at this timeVerticillium wilt susceptibility: susceptiblePest resistance: long-term health usually notaffected by pests

USE AND MANAGEMENT

This large shrub or small tree tends to leaf outearly, so it may be injured by spring frosts. Protectthem from drying winds and direct sun by providingexposure to partial or filtered shade and well-drained,acid soil with plenty of organic matter, particularly inthe southern part of its range. Leaves often scorch inhot summer weather in USDA hardiness zones 7b and8, unless they are in some shade or irrigated duringdry weather. More direct sun can be tolerated in thenorthern part of the range. Be sure drainage ismaintained and never allow water to stand around theroots. Grows fine on clay soils as long as the groundis sloped so water does not accumulate in the soil.Responds well to several inches of mulch placedbeneath the canopy.

Variegated types are a bit more difficult to growand are subject to leaf scorch. There are many

cultivars of Japanese maple with a wide variety of leafshapes and color, growth habits, and sizes:‘Atropurpureum’ - reddish leaves with five lobes;‘Bloodgood’ - new foliage bright red, darkening todark green; ‘Burgundy Lace’ - reddish foliage and cutleaves; ‘Dissectum’ - finely dissected leaves in greenor red, 10 to 12 feet tall; ‘Elegans’ - leaves withrose-colored margins when they first unfold;‘Ornatum’ - foliage is cut and reddish.

Pests

Aphids infest maples, usually norway maple, andmay be numerous at times. High populations cancause leaf drop. Another sign of heavy aphidinfestation is honey dew on lower leaves and objectsbeneath the tree. Aphids are controlled by spraying orthey may be left alone. If not sprayed, predatoryinsects will bring the aphid population under control.

Scales are an occasional problem on maples.Perhaps the most common is cottony maple scale. Theinsect forms a cottony mass on the lower sides ofbranches. Scales are usually controlled withhorticultural oil sprays. Scales may also be controlledwith well-timed sprays to kill the crawlers.

If borers become a problem it is an indication thetree is not growing well. Controlling borers involveskeeping trees healthy. Chemical controls of existinginfestations are more difficult. Proper control involvesidentification of the borer infesting the tree thenapplying insecticides at the proper time.

Diseases

Scorch occurs during periods of high temperaturesaccompanied by wind. Trees with diseased orinadequate root systems will also show scorching.When trees do not get enough water they scorch.Scorch symptoms are light brown or tan dead areasbetween leaf veins. The symptoms are on all parts ofthe tree or only on the side exposed to sun and wind.Scorching due to dry soil may be overcome bywatering. If scorching is due to an inadequate ordiseased root system, watering may have no effect.

Nutrient deficiency symptoms are yellow oryellowish-green leaves with darker green veins. Themost commonly deficient nutrient on maple ismanganese. Implanting capsules containing amanganese source in the trunk will alleviate thesymptoms. Test soil samples to determine if the soilpH is too high for best manganese availability. Plants

Acer palmatum -- Japanese Maple Page 4

exposed to weed killers may also show similarsymptoms.

Tar spot and a variety of leaf spots cause someconcern among homeowners but are rarely seriousenough for control.