Japanese aralia

Japanese aralia: how do you recognise it?

Habit

Broad, sparsely branched evergreen shrub of 2–4 m.

Leaf

Alternate, 20–40 cm across, palmate with 7–9 deep lobes, leathery and glossy, on a long stalk.

Stems

Thick, sparsely branched stems with large leaf scars.

Flower

Spherical umbels of creamy white flowers in large clusters, in October–November.

Fruit

Black berries in late winter and spring.

Difference from common ivy

Ivy is a climber with much smaller leaves, but with the same spherical flower heads in autumn.

Difference from × Fatshedera

A cross with ivy: smaller, five-lobed leaves and a semi-climbing habit.

Flowering: October–November · Pruning: April–May

Looks like it, but isn’t

• Common ivy Hedera helix: a climber with much smaller leaves, but with the same spherical flower heads in autumn. Difference from common ivy
• Fatshedera (× Fatshedera lizei): a cross with ivy: smaller, five-lobed leaves and a semi-climbing habit.

Why grow it?

• Huge, glossy leaves: an exotic eye-catcher for shade.
• Late flowers in October–November: nectar for hoverflies, wasps and bees.
• Grows in shade and in sheltered town gardens, also in a pot.
• Green all year round.

Japanese aralia: where does it grow best?

• Partial shade to shade; in full sun the leaves turn yellow and scorch.
• Sheltered from the wind: a courtyard, a town garden or the shade of a wall is ideal.
• Any free-draining, humus-rich soil that doesn’t dry out; no wet feet in winter.
• Allow 3 m width.

Light

Partial shade or shade

Legal basis

Any garden soil

Moisture

Normal

Size

3 m tall, 3 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Spotted laurel: Another evergreen for shade: speckled leaves next to the giant ones.
• Hydrangea: Flowers in summer in the same partial shade, the Japanese aralia in autumn.
• Chusan palm: A hardy palm for the same sheltered spot: together a tropical feel.

Good and bad companions

Goes well with

• Tolerates shade and suits planting under large trees such as: ginkgo, box elder, ash, honey locust, field maple, silver maple

Japanese aralia: when and how to plant it?

1. Plant in spring (April–May), so that it is well rooted before winter.
2. Dig a generous planting hole and mix in compost or leaf mould.
3. Plant at the same depth as before and water generously.
4. In a pot: choose a large pot with free-draining compost and move it to shelter in winter.

Care

Watering

In the first year and in dry summers: the large leaves lose a lot of water. Regularly in pots.

Feeding

A little compost or organic fertiliser in spring.

Mulch

A layer of leaf mould keeps the soil moist and protects the roots in winter.

Leaves

Cut off yellow or damaged leaves at the base of the stalk.

Tip: Plant it in the sheltered shade of a wall or courtyard: that is where its leaves grow largest and finest, and where it is best protected from frost.

Japanese aralia: when to prune it?

Pruning months: April–May.

When: In April–May.

How:

• Saw off overtall or bare stems low down; it sprouts again from the base.
• Every spring, remove damaged leaves and stems so that the plant stays fresh and compact.

Caution: In severe winters the leaves can be damaged by frost; only remove damaged leaves in spring.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Sowing

In spring, sow the seeds from ripe, black berries in a pot; keep them moist and frost-free.

Japanese aralia: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• In the ground it tolerates about −10 to −15 °C, especially in a sheltered spot; young plants and plants in pots are more vulnerable.
• In frost the leaves hang limply; after the thaw they usually perk up again. In hard frost the foliage is killed, but the plant sprouts again in spring.
• In hard frost, move pots against the house and wrap them.

Diseases and pests

• Scorched leaves: Yellow or brown patches on the leaves in full sun or wind. Give it a shadier, more sheltered spot.
• Frost damage: Black, limp leaves after a hard winter. Cut them off in April; new leaves will follow.
• Scale and mealybugs: Mainly on pot plants in a sheltered corner: scales or white fluff under the leaves, with sticky honeydew. Wipe them off or cut off affected leaves.

Through the year

• January: Wrap pots in hard frost.
• March: Black berries; leave frost-damaged leaves for now.
• April: Prune: remove damaged leaves and bare stems; plant.
• May: Last pruning month; plant.
• July: Water in dry spells.
• October: Flowering: white balls full of hoverflies and wasps.
• November: Flowering continues: late nectar.

What can you use it for?

Garden and landscape

Exotic foliage shrub for shade and sheltered town gardens; also in a pot.

For wildlife

In November the late flowers are a welcome source of nectar for hoverflies, wasps and bees.

Did you know?

• Related to ivy: in 1910 a nursery in Nantes crossed the two to create × Fatshedera, a plant halfway between a shrub and a climber.
• In the wild it grows in the shade of forests in southern Japan and Korea.