How to grow Japanese maples

Choosing a Japanese maple

Japanese maple trees have a variety of shapes, and their range of leaf colours, shapes and autumn colours makes for year-round interest, especially for smaller gardens.

Japanese maples can grow to 8m (26ft) in fifty years, depending on growing conditions, but most are small, slow-growing trees rarely more than 1-2m (3¼ft-6½ft) in height – ideal for the smaller garden or a container.

• Acer japonicum selections tend to make small spreading trees
• Acer palmatum selections are more shrub-like because they are broader than they are tall
• Both of the above still offer a variety of forms including upright, spreading and weeping forms

After thinking about what height and shape you would like, think about the leaf colour. It’s worth noting that the same leaves can be different colours at different times of year.

• Newly emerged leaves range in colour from yellow through lime-green to bright pink. They are usually palmate in shape with finger-like lobs or so finely cut to appear lace-like
• Autumn colour ranges from bright yellow through orange to intense red
• Red-leaved cultivars need some sun to develop a rich leaf colour

Japanese maples will grow well in a range of soils, so this doesn’t need to a big limiting factor on what you choose. However, they do best in soils that are well-drained and contain plenty of organic matter, such as garden

Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

Trees are available from most good garden centres, but a bigger range is available from specialist nurseries or at flower shows.

Japanese maples are widely sold as container-grown small trees, but may be available bare root from late autumn into winter from specialist nurseries. Choose a tree with a well-balanced framework of main branches.

The foliage of container grown trees should not show evidence of drying out such as browning along the leaf edges.

When to plant

Plant from early autumn through winter, so typically October to March.

Where to plant

• These slow-growing small trees are ideal for smaller gardens; but can make a great feature in any garden
• Japanese maples are hardy but do best in a spot sheltered from strong winds. Red-and purple-leaved cultivars need some sun to fully develop their dark hues. Variegated Japanese maples need partial shade to prevent the afternoon sun from scorching the foliage. Green-leaved forms tolerate full sun, but are best in dappled shade as very bright conditions can sometimes cause scorch
• Japanese maples do best in slightly acidic humus-rich, well-drained soils. They will be fine in most soils, however, you can improve them by digging in well-rotted organic matter such as garden compost or bags of garden centre soil improver. We have put together a guide to help you identify your soil type
• Japanese maples prefer space for their roots and do best if they do not have to compete with the plants around them so give them plenty of space
• Japanese maples like their roots quite shallow so plant them with no more than 2.5cm (1in) of soil over the main roots

How to plant

See our guide on tree planting for more information.

• Water in the tree to settle the soil and continue watering regularly, especially in dry weather, during the first summer
• Mulch with well-rotted organic matter, such as garden compost or mulching bark from a garden centre, so the soil does not dry out in summer

Growing in containers

Japanese maples are ideal plants for growing in containers. Plant in a John Innes No. 2 potting compost or a peat-free ericaceous with 25% added sharp sand, which gives good drainage.

Keep the compost moist, but not soaking wet, and feed in spring and early summer with a slow-release fertiliser or liquid feed.

Repotting

Your Japanese maple will need repotting into a slightly bigger container every couple of years. April or September are ideal months to do this.

Long-term container-grown trees will need root pruning every two or three years. To do this, place the pot on its side and remove the tree. Using an old saw cut 5cm (2in) off the bottom of the root ball and three or four slivers down the side. Tease out the roots on the surface of the compost and repot with fresh potting compost (same types as above). Place sufficient potting compost in the base of the pot so the tree is planted no deeper than previously.

The roots of maples in pots are vulnerable to frost over winter, so wrap containers with a sheet of bubble wrap, held in place with garden twine.

Watering

Water regularly in dry spells during the first year to aid establishment, especially if planted in spring or later in the summer season. You may need to water once a week during hot, dry spells which can cause the leaves to brown and crinkle around the edges. Water trees in containers regularly so they do not dry out. This can mean at least once a day in hot weather.

Feeding

Trees in the open ground don’t need feeding but a general-purpose fertiliser, such as Growmore, can be applied in late February each year at 70gm per sq m (2oz per sq yd) to encourage more growth. So trees do not dry out and to suppress weeds, mulch with a 10cm (4in) layer of garden compost or mulching bark. Do keep it away from the trunk as it will rot if covered.

Overwintering

Japanese maples in the ground are usually fully hardy, but container-grown trees should be placed on pot feet or brick and the pot wrapped in polythene bubble wrap for insulation.

Caring for older plants

Japanese maples are very long-lived but slow-growing.

Japanese maples naturally have an elegant shape and, when bought, usually require very little pruning other than removing any winter dieback at the ends of shoots. If young trees produce a strong vertical shoot this can be pruned back to a side branch in late autumn.

Japanese maples are best pruned when fully dormant (November to January), as maples bleed sap from pruning cuts at other times, weakening the tree. However, pruning is still best kept to a minimum as the most graceful shape comes from a tree that has been allowed to develop fairly naturally. As a result, just remove badly-placed or crossing shoots to encourage a good framework of branches to grow.

Where you do need to reduce height and width, follow long branches back to a side branch and prune it out at this point. This is not necessary on prostrate-growing trees because they should be allowed to spread naturally to gain the best effect.

Always prune back to a well-placed side branch. Do not leave a stub as this is often prone to decay and dieback.

See our guide to tree pruning.

Japanese maples can be grown from seed, but named cultivars/selections will not breed true. You can collect the winged seeds (samaras) when they fall in autumn. Sow them as soon as you can by removing the wings and sowing in a prepared seedbed (dug, trod, levelled and raked to create a surface of fine crumb-like soil) or sow in pots of seed compost, which are then placed in a cold frame or sheltered position outdoors over winter. The seeds germinate in spring.

Most maples are difficult to propagate from cuttings, so layering in autumn or early spring is probably the easiest way of propagating named cultivars. Commercial nurseries graft maples, but this is not an easy technique for most home gardeners as it takes a fair bit of practice to get good success.

Japanese maples are generally easy to grow if planted in shade, in a good soil, sheltered from strong winds. However, you might come across the following:

• Japanese maples can be very prone to leaf scorch in windy or excessively sunny positions, particularly those with fine-cut leaves. Young leaves can also be caught by frost so protect with horticultural fleece when cold nights are forecast
• Poor autumn colour or purple-leaved varieties turning green may suggest a lack of light, such as being in a very shady spot
• Japanese maples in containers may be troubled by vine weevil larvae, which eat their roots
• Japanese maples are susceptible to scale insect damage
• Phytopthora root rot and verticillium wilt can also be a problem on occasions