Japanese maples display spectacular foliage

Japanese maple (Acer palmatum).
Japanese maple (Acer palmatum).

They are among the most spectacular sights of autumn, as their leaves turn sizzling shades of red, burnt orange and yellow.

Japanese maples, or acers, may be expensive but they are still as popular as ever, possibly because there are varieties for almost every situation, even if you have the smallest urban garden.

With slow-growing types that are suitable for pots, larger varieties which can create stunning backdrops and those which will drape above smaller rock plants, in woodland settings or as a framework to ponds, there’s no excuse not to have a Japanese maple in your garden.

They will grow on acid or alkaline soils, need sun for good foliage colour but should be kept clear of biting winds, which will burn their delicate foliage, or drought, which will cause their leaves to go brown at the tips.

However, they’re not keen on chalk, so the soil needs to be lime free and preferably slightly acidic. I’ve had Acer palmatum var. dissectum ‘Garnet’ in ericaceous compost in a pot for five years and it has thrived, being kept well watered and sheltered from harsh winds. Replacing the surface compost of the pot with new compost every year will also help keep the nutrients flowing in a permanent planting.

Alternatively, plant them in large pots of John Innes loam-based compost for the best results, or a compost comprising equal parts John Innes No 2 and a soil-less multipurpose compost, which will hang on to water and nutrients effectively.

Among the best for autumn leaves is the Acer griseum, whose foliage turns orange and brilliant red in autumn, and which has the added interest of craggy, peeling bark in shades of orange-brown and cinnamon, which is most noticeable in winter when the tree is bear. It grows to a height of around 10m (30ft).

Others will grow happily in containers, providing architectural structure and colour in areas which need them. Varieties ideal for pots include A. palmatum ‘Garnet’ and ‘Corallinum’, which are slow-growing and will stay a manageable size in a pot, producing deep rich red foliage before leaf fall. Other good choices for autumn include the snake bark maples including Acer davidii ‘George Forrest’, with its red-stalked leaves, and the native field maple A. campestre, which has a broad, bushy habit and small green leaves which turn butter-yellow in autumn.

The coral bark maple, A. palmatum ‘Sango-kaku’, is renowned for its orange-red young stems which glow in winter light after the butter yellow autumn leaves have fallen. It’s a good choice for a smaller garden because it has upwardly sweeping branches as a young tree.

For those growing acers in containers, repot the plant every three to five years, either back into the same container with fresh compost, or into a slightly larger one.

Remove the plant from its pot, then gently tease out the roots and cut back any large, coarse ones. Put the tree in the new container then fill in with fresh compost so the root ball sits at the same level as before. Water well and mulch to suppress weeds.

If the leaves turn brown during summer, chances are your plant’s drying out. The leaves may also drop and the plant may appear dead, but if you water thoroughly and fork in well-rotted organic matter, it should recover.

Generally, Japanese maples don’t need pruning, but if you do want to keep it in check, just thin out overcrowded branches leaving the rest evenly spaced, or just shorten the branches which have grown out too far by cutting them back to a side-shoot. And only prune when the plant is dormant, from November to March.