Japanese garden juniper

Japanese garden juniper: how do you recognise it?

Habit

Low, creeping carpet about 30 cm high and 2 m wide, with branches lying flat on the ground.

Foliage

Evergreen; short, prickly needles, blue-green, with a light stripe on the upper side.

Fruit

Small, dark ‘berries’ (fleshy cones) on female plants, often only after many years.

Branches

Long, sturdy branches that creep along the ground and sometimes root by themselves.

Roots

Branching and deep; tolerates drought but not wet feet.

Plants: April–May and September–October · Pruning: May

Why grow it?

• Blue-green and dense all year: a lovely ground cover that suppresses weeds.
• Perfect for slopes, low walls and rock gardens, where the branches spill softly over stones.
• Very hardy and drought-tolerant, ideal for poor, sunny soil.
• Stays low and also suits small gardens and containers.
• Little work: almost no pruning and no feeding.

Japanese garden juniper: where does it grow best?

• Full sun; in shade the carpet becomes thin and loses its colour.
• Well-drained soil: sand, loam or clay, acid to chalky. Dry to moderately moist.
• Tolerates wind, drought and poor soil, but not a waterlogged spot or standing water in winter.
• Allow 1–2 m of space per plant; for a dense mat sooner, plant at 1 m.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Dry or normal

Size

0.3 m tall, 2 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Stonecrop: A succulent for dry spots with late flowers.
• Heather: A low, flowering patch of colour next to the blue-green carpet.
• Blue fescue: Fine, blue-grey foliage that goes with the blue-green needles.
• Crocus: Small bulbs that flower through the carpet in early spring.

Japanese garden juniper: when and how to plant it?

Plant in April–May and September–October.

1. Plant in April–May or in September–October, when the soil is neither frozen nor waterlogged.
2. Dig a hole twice as wide as the root ball; in heavy clay mix in sand or grit for better drainage.
3. Set the plant at the same depth as in its pot; the base of the stem must not end up deeper.
4. Water thoroughly straight away and keep the soil moist, but never wet, in the first year.
5. Cover the soil between the plants with grit or bark to suppress weeds until the carpet closes up.

Care

Water

In the first year, once a week in dry weather. After that it looks after itself, except in a container or during long droughts.

Feeding

Usually not necessary. On poor soil a thin layer of compost in spring is enough.

Weeding

Weed regularly in the first few years, until the branches cover the soil.

Removing leaves

In autumn, remove fallen leaves from the carpet, as they hold moisture and can cause rot.

In a container

Use a wide pot with drainage holes and compost mixed with sand or grit; water as soon as the top layer is dry.

Tip: Put it in full sun in a dry spot and let it spill over stones or a low wall. It grows slowly, so be patient.

Japanese garden juniper: when to prune it?

Pruning months: May.

When: It hardly needs pruning; trim in May where necessary.

How:

• Cut branches that spread too far or hang over the path back to a side shoot.
• Remove dead or damaged branches completely, back to living wood.
• If there are brown or dead needles, gently comb them out with your fingers or a rake.
• Wear gloves: the needles are prickly and can irritate sensitive skin.

Caution: Never cut into bare, brown wood: it does not regrow from there and leaves a gap.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Layering

Branches that touch the ground sometimes root by themselves. Pin them down; after a year you can sever and replant them.

Semi-ripe cuttings

In September–October: take 10–15 cm cuttings with a heel, in sandy compost in a cold frame. Rooting takes several months.

Japanese garden juniper: how does it get through the winter?

Hardy to −30 °C.

• Very hardy, to about −30 °C: no protection is needed in Belgian winters.
• On a slope or in a rock garden the water must drain away well; standing water in winter harms the roots.
• In a pot: place it in a sheltered spot and wrap the pot in hessian or bubble wrap so the roots do not freeze.

Diseases and pests

• Root rot: The plant declines and the foliage turns brown in a spot that is too wet. Plant in well-drained soil and do not overwater.
• Twig dieback: Brown, dying shoot tips. Cut affected parts back to healthy wood and dispose of them.
• Spider mites: In hot, dry summers the foliage turns grey-yellow and you see fine webs. Spray the plant with a jet of water.
• Weeds in the carpet: Weeds growing between the branches are hard to remove. Weed early, before the carpet closes up.

Through the year

• April: Plant. Remove dead branches.
• May: Plant. Trim branches that are too long.
• June: Water young plants in dry weather. Weed.
• July: Watch for spider mites in dry weather.
• August: Weed. Remove affected branches.
• September: Plant. Take cuttings.
• October: Plant. Take cuttings.
• November: Remove fallen leaves from the carpet.

Did you know?

• The species name procumbens means ‘lying flat’.
• The cultivar ‘Nana’ is very popular, both as ground cover and for bonsai.
• The species originally comes from Japan.