The Ultimate Guide to Growing a Japanese Maple
As the name suggests, these maples are native to Japan, growing as understorey trees in forests and the edges of woodlands.
Treasured for their dazzling autumn foliage display, they have been cultivated in Japan for centuries and in the West since the 1800s.
Deciduous small trees or large shrubs, Japanese maples are all slow-growing plants.
They are happy in full to part sun, as long as they have protection from harsh conditions.
Most grow to about four metres, though under ideal conditions some can reach 10m high.
Autumn colour can be red, green, yellow or purple in a variety of leaf shapes and sizes.
The best seasonal colour is shown in climates with clearly defined seasons.
Japanese maples must go dormant over winter, so they have a hard time surviving in climates where it doesn’t get cold enough.
The leaves have five, seven or nine lobes and are usually from 40 to 120mm long.
They range from the broad classic maple form to fine or cut leaves, which are heavily lobed, to filigree or dissected lace-like foliage, and even variegated.
The names of maples give a clue about the foliage. Atropurpureum means purple or red leaves and is used as a generic name as well as a particular cultivar.
These types prefer afternoon shade as their leaves discolour with too much sun or too much shade.
Dissectum varieties have finely cut leaves that can be barely thicker than the skeleton of the leaf veins.
These plants need protection from wind and hot sun, as they scorch easily.
TIP: Small-leafed Japanese maples are particularly popular as bonsai plants.
A popular type of dwarf maple is formed by grafting a fine-leafed Japanese maple with a weeping habit onto an upright understock.
The tree will generally grow only as tall as the understock, usually one or two metres.
Most commonly grown as a feature tree, they also take on starring roles in rockeries and in large pots.
Some have lollipop-like, straight forms, while others fall in rippling waves that would look at home in a Japanese watercolour.
In the garden Position maples in a protected spot, away from strong winds. In all but the coolest areas they do better in semi-shade.
Morning sun or dappled sunlight are the best options.
They like moisture in their shallow root run, so rich, friable, free-draining soil is best but any that isn’t heavy clay or very alkaline will do.
PLANT by digging a hole four times the width of the rootball and a little deeper.
Mix rich compost into the dug-out soil and fill the base of the hole.
Remove the plant from its pot and gently tease out any circling roots, then position it in the hole and backfill with enriched soil.
MULCH with 70mm of well-rotted organic mulch, keeping it at least 100mm clear of the trunk.
CARE for Japanese maples by watering regularly for the first three years.
They don’t need a lot of water but do need it in consistent amounts.
Check that there is sufficient moisture after rain, as shallow falls may evaporate quickly.
PRUNE in winter or summer, removing branches that spoil the shape of the tree and any that are diseased or crossing. Summer pruning stimulates less plant growth than winter pruning, so you can get away with cutting back a little more and the tree will stay thinned out for longer.
WATCH FOR sucking insects, as scale and mealy bug sometimes feast on young shoots.
They can be easily removed with a toothbrush or thumbnail, or sprayed with pest oil.
Aphids can also be a problem, use a soap-based spray or blast with a jet of water from the hose.
Caterpillars are a common problem, but just remove, drop and squash them.
Curl grubs are especially dangerous, chewing through the tree’s shallow root system, especially in pots.
Treat them with a spinosad-based insecticide like Yates Success.
Fungal problems can be an issue, especially in young plants and bonsai, so don’t overwater, plant too deeply or grow in heavy soil.
Repot a tree with fungal issues into a disinfected pot filled with fresh potting mix.
Leaf tips turning brown can be a sign of overwatering or of leaf scorch.
Adjust watering if needed, or consider moving the tree to a more protected part of the garden, or planting screening trees nearby.