The size of the Japanese maple differs by variety and cultivar. It can range from a shrub to a small tree. The shape is usually round or vase-like. It may also have a weeping shape. The Japanese maple tree is renowned for its striking foliage. The leaves have five to nine palmate lobes. They may come in green or red (or both). In the fall, the leaves will turn to brilliant shades of red, orange, yellow, or purple. There are many different textures of leaves. Some have wide lobes, while others are finely dissected and lacy in appearance. The small, inconspicuous flowers are red or purple; these become a dry winged fruit called a samara that is about a half-inch long. Japanese maple is planted in the fall.
Light
Grow Japanese maple in filtered sun to part shade. It is a suitable tree for full shade if needed, especially in the warmer zones, but different cultivars have different needs, so do some research before making a purchase. Afternoon sun is rarely tolerated by any cultivar, often resulting in sunburnt leaves.
Soil
Japanese maple trees like moist, well-drained soil. Loamy and sandy soil will work well, but avoid soil that has high alkalinity; Japanese maples thrive in slightly acidic soil.
Water
Although Japanese maples prefer well-draining soil, they also like to receive regular waterings. The easiest way to regulate the moisture level of the soil surrounding a Japanese maple is to mulch it. Until your tree is well-established, take the time to water it whenever the soil feels dry, particularly when it hasn’t been raining much.
Temperature and Humidity
Red-leaf varieties are more prone to leaf scorch than green varieties, that’s why in hot, dry climates, green-leaf varieties of Japanese maples are usually the better choice. The trees can usually withstand moderate humidity. Generally Japanese maples do best best in USDA zones 6 to 8 though some varieties thrive in zone 5 as well. Protect your Japanese maple from areas that experience strong winds.
Fertilizer
Hold off on fertilizing a newly planted Japanese maple and only feed it in the late winter or early spring of the second year. Trees with healthy foliage that are planted in rich soil with plenty of organic matter do not need annual fertilization. If you need to fertilize, do this in the spring. Apply a slow-release granular shrub and tree fertilizer and mix it at half the recommended rate for landscape trees. Do no apply a liquid fertilizer, as it can burn the roots. Spread the fertilizer evenly around the tree, starting at least 1 foot away from the trunk and beyond the tree’s drip line. As a rule of thumb, for every 5 feet in height, spread the fertilizer 1 foot beyond the drip line.
Types of Japanese Maples
There are hundreds of different varieties and cultivars of the Japanese maple in a range of sizes, colors, shapes, and leaf textures. Some notable cultivars include:
Acer palmatum ‘Coonara Pygmy’: This dwarf maple is a good choice if you plan on growing your Japanese maple tree in a container. It has pinkish leaves in the spring that turn orange-red in the fall. Acer palmatum ‘Villa Taranto’ is a weeping Japanese maple with delicate leaves that turn golden yellow in the fall. Acer palmatum ‘Wolff’ (also known as ‘Emperor I’) is one of the best cultivars for USDA zone 5 (and maybe even zone 4) with stunning purple foliage. Acer palmatum ‘Sumi nagashi’ is one of the faster-growing cultivars that grows well in USDA zone 5. Acer palmatum ‘Red Dragon’, a laceleaf weeping maple with bright red, cherry-colored leaves in the spring that become darker over the summer and turn scarlet in the fall Acer palmatum ‘Bloodgood’ grows to a maximum size of 20 feet high with a similar spread. It has reddish-purple leaves in the summer and is greener in full sun. The leaves deepen to crimson red in the fall. Acer palmatum ‘Crimson Queen’ with a height of 8 to 10 feet and a spread of 10 to 12 feet has a weeping habit and dissected leaf type. The dark-red summer leaves deepen to crimson. Fall colors include yellow, red, purple, and bronze.
Pruning
Japanese maples need very little pruning. Only prune out the lower branches if desired and remove any branches that have crossed for improved appearance. Other than that, simply remove any dead, diseased, or damaged branches. You can also control the appearance of the Japanese maple by choosing whether to train a single trunk or to allow multiple trunks to form.
Propagating Japanese Maples
You can propagate a Japanese maple with softwood cuttings taken in the summer: Another, more involved method of propagating a Japanese maple is by grafting. It involves joining the rootstock of a closely related species with the scion or upper stock of the cultivar. Grafting is usually done in the winter:
Growing Japanese Maple Trees from Seed
As most Japanese maples sold are cultivars, the tree that will grow from its seeds will not have the same desirable features as the parent. Given the length of the process and the unpredictability of the result, it is not recommended to start a Japanese maple from seed but propagate it from cuttings instead.
Potting and Repotting Japanese Maples
Aside from their use in bonsai, dwarf Japanese maples can also be grown as container trees and moved about the yard throughout the season. Plant them in a container with adequate drainage holes since Japanese maples do not do well in soggy soil. A terra cotta pot works well as it wicks away extra moisture. Japanese maples don’t like to have their roots sitting in water so choose a well-draining high-quality potting soil. Repot once roots reach the sides and bottom of the pot, or grow out of the drainage holes.
Overwintering
Japanese maples are hardy to USDA zone 5 but container plants need some protection during the winter. Move the container to an outdoor location where it is shielded from strong damaging winds. To protect the roots against the cold (in a container, they are much less insulated than in garden soil), wrap the container in burlap and bubble wrap, or protect it with an insulating silo.
Common Pests and Plant Diseases
Japanese maples are susceptible to a various pests, including aphids, mealybugs, scale bugs, mites, borer, and Japanese beetles, which can defoliate a Japanese maple in no time. Aphids and mealybugs can be washed off with a garden hose. For the other pests, you might have to use insecticidal soap or neem oil, or, if the infestation is so heavy that it cannot be treated with organic pesticides, use chemical pesticides as a last resort. Japanese maples are also susceptible to cankers, verticillium wilt, a soil-borne fungus that leads to premature yellowing of the leaves an leaf drop, as well as powdery mildew, anthracnose, and sooty mold.
Common Problems with Japanese Maple
If your Japanese maple tree is struggling, it could also be one of these common issues:
Twig Kill
Twigs dying is usually a sign of insufficient water. Water the tree slowly but deeply to restore its vigor and repeat it regularly to prevent a recurrence.
Manganese Deficiency
The most common nutrient deficiency of Japanese maples is a lack of the micronutrient manganese, which manifests itself as yellow or yellowish-green leaves with darker green veins. The treatment consists of injecting manganese in the tree trunk (capsules are available from arborist supply stores). But before you take action, do a soil test to make sure the tree is indeed suffering from lack of manganese.
Sunburn
Japanese maples are highly susceptible to sunburn on the trunks and branches so be very careful not to prune too many low or interior branches. Removing those branches can expose those areas to the sun, leading to significant damage. Similarly, be careful about pruning trees when your Japanese maple is an understory tree. Sudden exposure to sun will have detrimental effects on your tree. If you must increase sun exposure, try to do so slowly over the course of at least two seasons.
