How to grow Japanese maples

With their delicate leaves and naturally graceful shape, Japanese maples (Acer palmatum) are a top choice for many gardeners wanting to add some permanent structure to their outside space. They're ideal for growing in pots as well as in the ground, and their autumn colour is well known, but many have leaves that are colourful throughout spring and summer, too. As garden space is at a premium for most people, and a tree is often an expensive investment, we wanted to find varieties of Japanese maple that will earn their place with a long-lasting display.

Which? Gardening magazine worked with the experts at Westonbirt Arboretum to find the best varieties.

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Key facts

PLANT TYPE Small tree or large shrub

POSITION Part shade, some sun

SOIL  Moist but well drained

How to grow Japanese maples: month by month

Best Japanese maple varieties

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How we test Japanese maples 

Maples are slow growing, and we wanted to be able to assess mature trees, so we worked with Westonbirt Arboretum in Gloucestershire on this test. It holds the national collection of Acer palmatum and grows nearly 300 different cultivars. We chose 25 that are popular varieties and widely sold. The trees were assessed fortnightly by volunteers at the arboretum, who recorded the progress and appearance of the trees from March to November. We also visited in spring, summer and autumn, so we could take more detailed records of the trees in the peak spring and autumn seasons for colour, and to see what they looked like through the rest of the growing season.

Caring for your plants

Planting in the ground

Choose a sheltered spot that has shade during the middle of the day in summer. Although some acers need acidic soil, Japanese maples can be grown in alkaline or neutral soil. Plant in well-prepared soil, in a hole that’s the depth of the pot but slightly wider. Hammer in a tree stake at a 45-degree angle next to the trunk, and secure the trunk to the stake with a tree tie. Water and then mulch with 5 to 7.5cm of well-rotted organic matter, such as garden compost or spent mushroom compost, keeping it away from the trunk.

Plants in the ground shouldn’t need feeding. Add a 5 to 7.5cm-deep mulch of organic matter each spring.

Water during prolonged dry spells of weather.

Planting in a container

Choose a large container. Use a Best Buy compost for patio pots and add controlled-release feed. There’s no need to add crocks to the bottom of the pot, as these will impede drainage.

In a container, water often in warm weather so the compost doesn’t dry out.

Repot into a larger container if needed, or remove the top layer of compost each spring and replace with fresh compost mixed with controlled-release feed.

Protect the roots from freezing in a pot by moving it to a sheltered spot or by wrapping it in bubble wrap or fleece. 

Pruning

No routine pruning should be needed. If you want to prune to control the size, do this between leaf fall and the end of December, when the tree is completely dormant.

Common growing problems

Dieback

Japanese maples are prone to sudden die-back of branches, often caused by the soil-borne fungus verticilium wilt. Cut out branches that have died during the dormant period. A high-nitrogen feed and regular, heavy watering might help the plant recover, but if severely affected it will need to be removed.

Frazzled leaves

Leaves turning brown at the edges, curling, shrivelling and sometimes dying is a common problem with Japanese maples, especially those with more feathery, paler or variegated leaves. It can be caused by frost, cold, drying winds, dry or wet soil and sun. Keep them moist but not wet, especially when grown in pots or newly planted. Place in dappled shade and protect from cold winds. If late frost is predicted after the new leaves have emerged, cover the tree with fleece or move a pot-grown tree to shelter until the risk has passed.