Trident maple

Trident maple: how do you recognise it?

Habit

Small tree or large shrub, 6–8 m tall and up to 6 m wide, with a rounded to broad crown; often multi-stemmed.

Leaves

4–8 cm, with three short, forward-pointing lobes; glossy dark green, paler beneath. Orange, red or yellow in autumn.

Flower

Small greenish-yellow flowers in clusters in April–May, together with the young leaves; not showy.

Fruit

Winged double fruits 2–3 cm long with almost parallel wings, which spin down like little propellers in autumn.

Bark

Grey-brown; on older trunks it flakes off in small plates, revealing orange-brown patches.

Flowering: April–May · Plants: March–April and October–December · Pruning: July–August

Why grow it?

• A small tree that fits an ordinary garden, as a single-stemmed specimen or multi-stemmed.
• Glossy, fine three-lobed leaves with orange to red autumn colour.
• On older trees, attractive flaking bark that also looks good in winter.
• Takes pruning well and can be kept in shape, even in a large pot.
• A classic species for anyone who wants to train their own bonsai.

Trident maple: where does it grow best?

• Sun to partial shade; a warm, sheltered spot gives the best autumn colour and the firmest wood.
• Humus-rich, well-drained soil: sand, loam or clay, acid to neutral.
• Moderately moist: not too dry and certainly not waterlogged.
• Sheltered from cold, drying east winds, which can scorch the young leaves.
• Allow 5–6 m of space and plant it at least 3 m from buildings.

Light

Sun and partial shade

Soil type

Sand, loam or clay

Acidity

Acid or neutral

Moisture

Normal

Size

8 m tall, 6 m wide

Hardiness

Hardy (to -20 °C)

Goes well with

• Japanese forest grass: Graceful, arching tufts beneath the crown, also from East Asia.
• Hosta: Large leaves as a contrast to the fine maple foliage.
• Barrenwort: A tough, low ground cover for the partial shade under the tree.
• Crocus: Early flowers beneath the bare branches, before the leaves break.
• Japanese anemone: Flowers in late summer and autumn, just before the autumn colour.

Trident maple: when and how to plant it?

Plant in March–April and October–December.

1. Plant in March–April or from October to December, when the soil is not frozen or too wet.
2. Dig a hole twice as wide as the root ball and mix in some compost.
3. Set the tree at the same depth as it was in the pot: the root flare must not disappear below the soil.
4. Secure a standard tree to a stake on the windward side and tie it loosely with a tree tie.
5. Water well straight away and keep the soil moist during the first year.
6. Spread a mulch of leaf mould or wood chips round the base, keeping it off the trunk.

Care

Water

In the first year, water weekly in dry spells. After that, only in long dry periods.

Feeding

A little compost round the base in spring is enough; too much fertiliser gives soft wood and poorer autumn colour.

Mulching

A layer of leaf mould in spring keeps the roots cool and moist.

In a pot

In a large pot of free-draining compost it can stay attractive for years. Water regularly in summer and repot every two to three years in March.

Shape

For a multi-stemmed tree, keep three to five stems from an early age.

Tip: Give it a warm, sheltered spot and prune only in summer: it will then form firm wood, a handsome crown and vivid autumn colour.

Trident maple: when to prune it?

Pruning months: July–August.

When: Prune only when needed, in July–August, when the tree is in full leaf.

How:

• Remove dead, diseased and crossing branches, just outside the branch collar.
• Cut out water shoots and suckers at the base of the trunk.
• Keep pruning wounds small: better to remove a few branches than to shorten the whole crown.
• In a pot or as a bonsai, cut new shoots back to one or two pairs of leaves in summer.

Caution: Do not prune from January to May: the sap is rising and maples ‘bleed’ heavily from the wounds.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Softwood cuttings

In June: 10 cm cuttings from young shoots, lower leaves removed, in moist cutting compost under plastic. They root fairly easily.

Seed

Sow ripe seed in a pot in autumn and stand it outside in the cold; the seedlings come up in spring.

Layering

In spring, nick a low branch, peg it into the soil and sever it after a year.

Trident maple: how does it get through the winter?

Hardy to −20 °C.

• Hardy to about −20 °C: in Belgium it survives normal winters without protection.
• Shelter young trees and trees on a cold, exposed site from strong east winds.
• In a pot: stand it against a wall, wrap the pot in hessian or bubble wrap and raise it on pot feet.
• Late frosts can brown the young leaves; the tree usually comes back into leaf afterwards.

Diseases and pests

• Verticillium wilt: Branches suddenly wilt in summer, with brown streaks in the wood. Cut affected branches well back into healthy wood and disinfect your secateurs; there is no cure.
• Aphids: Sticky young leaves in May–June. Ladybirds and parasitic wasps usually clear them up; otherwise hose them off with water.
• Leaf scorch: Brown leaf edges from cold wind in spring or from heat and drought. Choose a sheltered site and water in dry spells.
• Coral spot: Small pinkish-orange pustules on dead twigs. Cut dead wood back into healthy wood.

Through the year

• March: Plant. Give compost round the base. Repot potted trees.
• April: Plant. Small greenish-yellow flowers with the young leaves.
• May: Flowering. Watch for aphids.
• June: Take softwood cuttings. Water in dry spells.
• July: Prune if needed. Water in dry spells.
• August: Last pruning. Water potted trees regularly.
• October: Orange to red autumn colour. Plant. Sow ripe seed.
• November: Plant. Move potted trees to shelter.
• December: Plant in frost-free weather. Wrap pots.

Did you know?

• The species name honours Heinrich Bürger, who collected plants in Japan in the 19th century together with Philipp Franz von Siebold.
• It is one of the most popular species for bonsai: the trunk thickens quickly and the roots readily grow over a stone.
• The winged double fruit spins down like a propeller, so the wind carries the seed a little way from the tree.