Japanese Maple

Classification:
Kingdom: Plantae
Phylum: Angiosperms
Family: Sapindaceae
Genus: Acer
Species: A. palmatum

As the name implies Japanese maple is a woody plant species native to Japan. It is also found in Korea and China. It is now grown in many parts of the temperate world and many different cultivars with attractive leaf shapes and colors are available. It is popularly used in Bonsai.

It is a deciduous widely spreading shrub or a small tree that does not reach over 10 meters and rarely grows to over 16 meters. Very few are dwarfs between 1-2 meters. It does not have a central leader, instead may have multiple trunks joined at almost ground level. Leaves are about 4-12 cm long and are wide palmate, with 5, 7 or 9 acutely pointed lobed foliage. It produces flowers in small cymes. A flower displays five whitish petals and five red or purple sepals. The fruits 2- 3 cm long are winged containing a seed of about 6-8 cm on one side. The wing extends to the other side to send the seed spiraling as it falls. They are called samaras. They don’t readily germinate and may require stratification to release the seed for germination. It is common to sometimes call it a key or whirlybird, whirligig or helicopter by the way it’s seen fall.

Seedlings from a same parent tree can display different genetic variation in its size, shape and color of leaves and is common even in specimens found in nature. There are known to be over a 1,000 cultivars selected for particular characteristics, propagated from cuttings, tissue culture or bud grafts. Leaf color ranges from red to dark purple, chartreuse through to dark green and in variegated foliage of pink and white. Mutations and artificially selected specimens grown over many generations appear as distorted or dwarfed types and are suitable for use as pot plants.

They need a period of cold dormancy and good air circulation. They will do well with morning sun and afternoon shadow and need to be protected from strong wind. Too much and deep shaded areas will make most red cultivars to turn green. Therefore some amount of sun is required to bring out good fall color. During fall the samaras can turn in shape and change color and the bark can also become brightly colored in winter.

Their appearance is broadly responsive to exposure to sun and shade, type of soil, moisture content present in the soil, fertilization and other environmental conditions. Many are known to behave differently changing colors and combinations of color thorough the year.

Generally plants with red foliage are named ‘Bloodgood’ and ‘Atropurureum’ and lacey types as ‘Dissectum’, ‘Lace Leaf’ and ‘Filigree’ while some varieties have golden fall foliage (e.g., Acer shirasawanum ‘Aureum’)

Japanese maples are fairly quick starters till they are about half their natural mature height, but slow in reaching their full height.

Some varieties may be grown as pot plants but are not recommended as house plants. They don’t care for hot or humid tropical conditions.

Japanese maples are required to be especially taken care of during the first year, making sure that a regular watering program is carried out to keep the soil evenly watered and ensure that the soil is never too soggy and never dry. Watering is best done in the mornings and applied at the base where it is needed most. Don’t allow water on the leaves if there is sunlight on them as it can cause leaf burn as sunlight becomes magnified with water. Remember when watering; apply up to the drip line as a tree’s roots are extensively spread.

Apply fertilizer lightly during spring, mulching with an organic mix in the fall but never too close to the trunk. Use a balanced fertilizer in the NPK ratio of 7-9-5 or 10- 10-10 . In summer months it will help to keep the soil moist and cool if a mulch of bark, or any suitable matter is applied.

Scales and Aphids are insect pests that can infest Japanese maples. Leaf drop or honeydew which causes the growth of sooty mold on the foliage and surfaces below it is a cause of a heavy attack though neither insect will cause death. The Japanese beetle is another leaf feeder. Borers are other insects to watch out for. Greatly Japanese maples are more susceptible to bacterial and fungal diseases and the major foliar diseases are anthracnose, phyllosticta leaf spot and pseudomonas tip blight seen as leaf spot diseases disfiguring leaves and causing early defoliation. This is preventable if there’s good drainage and air circulation. Phytopthora root rot and root collar canker are commonly associated with wet areas. Other problems that produce symptoms similar to wilting in drought can be caused by the vascular disease verticilliun wilt, initiated but root infection. The entire tree can be killed by this. Soil nematodes feed on the toots allowing the entry of verticillium. Most of these may be controlled by spraying with a copper based spray or a bioengineered product obtained from a garden centre.

Protect the Japanese maples from scorching which may be a problem during periods of raised temperatures that’s accompanied by wind and cause excessive drying out even in a minor drought. For this reason it is best to plant Japanese maples in a sheltered and a bit shady area. Keep them watered well during dry spells. Tan dead areas and margins of foliage including twig die back indicate scorch.

Japanese maples are typically slow growers and pruning will only retard their root formation and growth. If they don’t physically interfere or are in the way they don’t need to be pruned at all. But do remove all growth below the grafting. Allowing this to grow which is of stronger root stock will inhibit the growth of your plant. Corrective pruning can be done any time while any major pruning is required which is doubtful, do it just before leaf fall