Amur cork tree

Amur cork tree: how do you recognise it?

Habit

Broad, open crown with sturdy, arching branches; about 12 m tall and 12 m wide.

Leaves

Pinnate, 25–35 cm long, with 5–13 glossy dark green leaflets; aromatic when crushed; yellow in autumn.

Bark

On older trees thick, corky, light grey and deeply furrowed; the inner bark is yellow.

Flowers

Small greenish-yellow flowers in loose panicles, in June; male and female flowers grow on separate trees.

Fruit

Female trees carry clusters of small, black, aromatic berries about 1 cm across, which stay on the tree into winter.

Roots

Spreading and not very deep; it is not fussy about the soil.

Flowering: June · Plants: March–April and October–December · Pruning: February

Why grow it?

• A good bee tree: the June flowers provide nectar and pollen.
• Striking corky bark on older trees, with attractive relief in winter.
• Pinnate, aromatic leaves that turn yellow in autumn.
• Very hardy, to about −35 °C, and undemanding.
• Gives broad, airy shade in summer.

Amur cork tree: where does it grow best?

• Full sun for the finest crown and autumn colour.
• Ordinary, well-drained garden soil: sand, loam or clay, acid to chalky.
• Normally moist; once established it also tolerates dry spells.
• Tolerates wind and town air well.
• Allow 12 m width and keep well away from buildings and pipework.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Normal

Size

12 m tall, 12 m wide

Hardiness

Hardy (to -35 °C)

Goes well with

• Cranesbill: A sturdy ground cover for beneath the crown that also copes with drier soil.
• Lady’s mantle: Soft green leaves and yellow flowers at the foot of the tree.
• Daffodil: Flowers in spring, before the tree comes into leaf.
• Snowdrop: An early flowerer beneath the bare crown.

Amur cork tree: 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 neither frozen nor waterlogged.
2. Dig a hole twice as wide as the root ball and just as deep. Loosen the sides so the roots can grow out easily.
3. Set the tree at the same depth as in its pot or root ball: the root collar stays at soil level.
4. Add a stake and tie the trunk loosely with a tree tie. Keep 8–10 m away from buildings and other trees.
5. Water generously straight away, even if it is raining.
6. Spread a 5–8 cm layer of mulch (leaf mould or wood chips) around the tree, keeping it clear of the trunk.

Care

Water

For the first two years, water generously every week in dry spells. After that it almost always manages on its own.

Feeding

Usually not needed. On poor soil, give some compost or organic fertiliser in March.

Mulching

A layer of leaf mould or wood chips keeps the soil moist and suppresses weeds.

Stake

Leave the stake in place for 2–3 years and check that the tie does not cut into the bark.

Seedlings

Female trees self-seed via birds: pull out seedlings in spring before they take root.

Tip: Plant it in a spacious spot and, where possible, choose a male tree: it bears no fruit and so does not self-seed. The corky bark only develops after many years.

Amur cork tree: when to prune it?

Pruning months: February.

When: It needs little pruning. Give young trees a light formative prune in February, in dry, frost-free weather.

How:

• On a young tree, choose a single continuous trunk and remove a double leader.
• Remove dead, diseased, crossing and rubbing branches with a sharp saw or secateurs.
• On a high crown, gradually remove the lowest branches if you want more room beneath the tree.
• Otherwise leave the broad, open crown alone: do not shorten the tree.

Caution: Do not prune in full growth in spring: large wounds heal more slowly then.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Pick the fruits in autumn, remove the flesh and leave the seeds cold and moist for a few months (for example outdoors in a pot, or in sand in the fridge). Sow in spring.

Root cuttings

In winter, set pieces of root 5–8 cm long upright in potting compost; some will take. Nurseries also propagate selections by grafting.

Amur cork tree: how does it get through the winter?

Hardy to −35 °C.

• Very hardy, to about −35 °C: no protection is needed in Belgium.
• On a young tree, a layer of mulch protects the roots during the first winters.
• The corky bark and the black berries on female trees are also an attractive detail in winter.

Diseases and pests

• Unwanted seedlings: Birds spread the seeds of female trees. Pull out seedlings while they are small, or choose a male tree.
• Brown leaf edges: In heat or long drought the edges dry out. Water young trees generously and mulch the root zone.
• Root rot: Wilting leaves in soil that stays wet for long. Plant on a well-drained spot and do not overwater.
• Aphids: Sticky leaves and small insects on young shoots. Spray them off with a strong jet of water; ladybirds and birds help.

Through the year

• February: Give young trees a light formative prune in dry, frost-free weather.
• March: Planting is possible. Fit a stake, apply mulch.
• April: Plant. Pull out seedlings. Water new plantings in dry weather.
• May: The leaves unfurl. Water young trees in dry weather.
• June: Flowering: bees on the blooms. Water in dry weather.
• July: Water young trees in dry weather.
• August: Water young trees in hot weather.
• September: The fruits of female trees turn black.
• October: Yellow autumn colour. Plant.
• November: Plant. Mulch around young trees.
• December: Planting still possible in mild weather. Rest.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• Phellodendron literally means ‘cork tree’ (Greek phellos = cork, dendron = tree); amurense refers to the Amur region in north-eastern Asia.
• Despite its name, it does not supply the cork for wine bottles: that comes from the cork oak.
• It is related to citrus: both belong to the rue family, which explains the aromatic smell of the leaves.