How to grow larger acers

Choosing a larger maple

Maples are usually chosen for their colourful foliage and their interesting bark. The foliage can be variegated or brightly coloured in shades of yellow, red or purple and their autumn colour is often spectacular. Which you choose may depend upon the colour you want. The typical maple leaf is large, fan-shaped (palmate) and divided into five lobes, but many variations occur so it’s worth considering whether a particular shape suits your overall design.

Some maples have attractive bark overlaid with vertical whitish lines. These are known as snakebark maples and are a good choice if you’re looking for winter interest. Others have brightly-coloured new shoots or, as in the case of Acer griseum, curls of peeling bark.

Maples vary in size. Some are only suitable as specimen trees for larger gardens, but others are suitable for smaller suburban gardens. Check plant labels for details. Those with attractive new shoots you can pruned to keep compact. Most larger maples are unsuitable for container growing – so consider instead a Japanese maple instead.

Buying a larger maple

Garden centres offer a limited range of potted plants, but more are available online from specialist tree nurseries. Trees are usually sold with a clear trunk (half-standard) and pruned to form a well-branched head or with a strong main shoot (central leader) or as multi-stemmed trees. To source specific ones you can use the RHS Find a Plant tool.

When to plant

You can plant larger maples from early autumn through winter.

Where to plant

• Maples do best in full sun or light shade
• 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
• These trees do best in a neutral to slightly acidic humus-rich, well-drained soils. They will be fine in most soils that are not waterlogged or very dry in summer, especially if you improve the soil 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
• Maples will look good as specimen trees planted on their own or among a mixed planting of trees and shrubs

How to plant

See our guide on tree planting for information.

• Trees may need staking to keep them stable
• Water in the tree to settle the soil and continue watering regularly, especially in dry weather, during the first summer
• Mulch your larger maple 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

Watering

Water regularly in dry spells during the first two years to aid establishment, especially if planted in spring or later in the season.

Feeding

Trees in the open ground rarely need feeding. To prevent trees drying out, and to suppress weeds, mulch with a 10cm (4in) layer of garden compost or mulching bark. Just make sure the mulch doesn’t butt up to the trunk as this would cause it to rot.

Overwintering

Larger maples are fully hardy and need no winter protection.

Maples bought as two- or three-year-old trees will have been formatively pruned to create a well-shaped tree.

If you need to do any pruning, prune your larger maples when they are fully dormant (November-January) or in late summer (August-October), as they bleed sap from pruning cuts at other times, weakening the tree.

You can enhance the appearance of maples with brightly-coloured new shoots by pruning to a short trunk before mid-winter to create more shrubby growth – this makes them better for small gardens too.

To achieve this, prune your young tree in the first winter to about 50cm (16in), just above two pairs of strong shoots. Shorten these shoots by about a third to encourage them to branch in the spring. Acers are very prone to bleeding from pruning cuts so it’s best to do this before the end of January while they are totally dormant.

In the second winter prune out any dead or damaged shoots and shorten the main shoots back a little.

In the third winter remove any very low branches to display the bark on the trunk. Also, remove any shoots growing into the centre of the tree to prevent overcrowding.

Garden maples can be grown from seed, but seedlings rasied from named selections/cultivars will not generally look the same as the original tree. 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, but you can propagate more vigorous snakebark maples from softwood cuttings in early summer. Commercial nurseries graft maples but this is not an easy technique for most home gardeners as it needs a bit of practice to get a good success rate.

Maples are generally easy to grow if planted in a good soil sheltered from strong winds.

• Maples can be prone to leaf scorch in windy or excessively sunny positions. Young leaves can also be caught by frost
• Maples pruned at the wrong time of year (January-July) will bleed from pruning cuts
• Poor autumn colour or purple-leaved varieties turning green may suggest a lack of light, such as being in a very shady spot or where larger trees have overhanging branches. Prune if possible to reduce shade from other plants
• Maples are susceptible to Phytopthora root rot in wet soils. Verticillium wilt can also be a problem.
• Maples in dry soils may suffer from powdery mildew