Japanese holly

Japanese holly: how do you recognise it?

Habit

Densely branched evergreen shrub of 1–3 m; usually kept low in gardens.

Leaf

Alternate, 1–3 cm, oval, finely scalloped, leathery and glossy dark green; without spines.

Twigs

Greyish-brown, densely branched twigs.

Flower

Inconspicuous white flowers in May–June; male and female on separate plants.

Fruit

Glossy black berries on female plants; not edible.

Difference from box

Box has opposite, untoothed little leaves.

Difference from holly

Holly has much larger, spiny leaves and red berries.

Flowering: May–June · Pruning: May–June and August–September

Identify by feature: Evergreen leaves · Black berries

Looks like it, but isn’t

• Box Buxus sempervirens: opposite, untoothed little leaves. Difference from box
• Holly Ilex aquifolium: much larger, spiny leaves and red berries. Difference from holly

Why grow it?

• A replacement for box that is not troubled by box tree moth or box blight.
• Evergreen and easy to clip: as a low hedge, ball or topiary.
• Grows in sun and partial shade, also in a pot.
• Dense shelter for small birds.

Japanese holly: where does it grow best?

• Sun or partial shade; in deep shade it becomes sparse.
• Acid, humus-rich soil that stays moist but drains well.
• No chalky soil, where the leaves turn yellow, and no heavy, wet soil, where it may die back.
• Also in a pot or trough, with ericaceous compost.

Light

Sun or partial shade

Legal basis

Acid soil

Moisture

Normal

Size

2 m tall, 1.5 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Hydrangea: Also likes acid, moist soil: a crisp green edging around a looser flowering shrub.
• Japanese maple: A Japanese garden scene: green balls beneath the delicate foliage of the maple.
• Rhododendron: The same acid, humus-rich soil; green all year round.

Good and bad companions

Goes well with

• Suits the woodland edge or the light shade of: english oak, sessile oak, pin oak, turkey oak
• Like acid soil, just like this plant: heather, rhododendron, japanese skimmia, raspberry, highbush blueberry, witch hazel, broom, gorse

Japanese holly: when and how to plant it?

1. Plant in spring (March–May) or early autumn (September–October), root-balled or from a pot.
2. For a low hedge: 5–7 plants per metre. Compact varieties such as ‘Dark Green’ are the ones mostly sold for small hedges.
3. On heavy soil, mix sand and leaf mould into the planting hole.
4. Plant at the same depth as before, water generously and keep the root ball moist during the first year.

Care

Watering

Regularly in the first year; after that during prolonged drought. More often in pots.

Feeding

A little leaf mould or ericaceous fertiliser in spring.

Mulch

A layer of leaf mould or wood chips keeps the roots cool and moist.

Clipping

Twice a year for a crisp shape (see pruning).

Tip: Replacing a box hedge? Look at the soil first: box likes chalk, Japanese holly does not. On chalky soil it is not a good substitute.

Japanese holly: when to prune it?

Pruning months: May–June and August–September.

When: In May–June and in August–early September.

How:

• Trim in overcast weather, so that the cut leaves don’t scorch in the sun.
• For a crisp shape, trim twice a year; once is enough for a looser hedge.
• It also sprouts from older wood: a plant that has grown too big or bare can be cut back hard.

Caution: Don’t trim after early September: the new shoots still need to harden off before the frost.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings

In July–August, take semi-ripe cuttings of 8–10 cm and root them in sandy compost under glass or plastic; they take readily.

Japanese holly: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Hardy in Belgium and the Netherlands.
• In hard frost with sun and a cold wind, the leaves may scorch brown. Plants in pots are more vulnerable: move them to shelter and water them on frost-free days.

Diseases and pests

• Wet feet: On heavy, wet soil, branches or whole plants die from root rot. Plant it in a free-draining spot.
• Yellow leaves: On chalky soil the leaves turn yellow between the veins. Choose another plant there, or grow it in a pot with acid compost.
• Drought: In drought it sheds leaves and becomes bare, especially in pots and in the first year. Water in good time.

Through the year

• March: Plant root-balled or pot-grown plants.
• April: Feed and mulch.
• May: First trim; small white flowers.
• June: Trim in overcast weather.
• July: Take cuttings; water in dry spells.
• August: Second trim.
• September: Last trim in early September; plant.

What can you use it for?

Garden and landscape

Low hedge, ball or topiary instead of box; also in pots.

For wildlife

Dense shelter for small birds.

Caution: Dislikes chalky soil and wet feet: on heavy, waterlogged ground it sometimes dies back.

Did you know?

• Box tree moth and box blight leave it alone; that is why it is replacing box in many gardens and parks.
• Despite looking like box, it is a true holly, related to our native holly, but with black berries and no spines.