Japanese black pine

Japanese black pine: how do you recognise it?

Habit

Sturdy, irregular pine up to about 15 m tall and 8 m wide, with an often curved trunk and, in time, a broad, flat-topped crown.

Needles

Two per bundle, 7–12 cm long, stiff and dark green, sharp at the tip.

Buds

Large, silvery-white winter buds, a good clue to identification.

Cones

Egg-shaped cones of 4–7 cm that ripen brown.

Bark

Dark grey to black and deeply fissured into plates on older trees.

Roots

Deep-rooting; it transplants best when young and with a rootball.

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

Why grow it?

• Tolerates wind, salt and poor soil: also suitable for gardens on the coast.
• Picturesque, irregular habit with a dark, deeply fissured trunk.
• Evergreen, with dark green needles and striking silvery-white buds in winter.
• Typical of Japanese gardens and bonsai, and easy to shape by pinching the candles.
• Drought-tolerant once established.

Japanese black pine: where does it grow best?

• Full sun; in shade it grows thin and irregular.
• Poor, well-drained sandy or loamy soil, acid to chalky; it is not fussy as long as water can drain away.
• Dry to moderately moist; it tolerates drought and sea wind, but not wet feet.
• Allow 6–8 m of free space for a mature tree; you can keep it smaller by pinching every year.

Light

Sun

Soil type

Sand or loam

Acidity

Not fussy

Moisture

Dry or normal

Size

15 m tall, 8 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Japanese maple: Finely cut foliage and wonderful autumn colour, a classic in the Japanese garden.
• Rhododendron: An evergreen underplanting that flowers in May; choose a light spot at the edge.
• Ornamental grasses: Soft, flowing tufts that go well with the dark, structured pine.
• Heather: A low, flowering ground cover for poor, sunny soil.

Japanese black pine: when and how to plant it?

Plant in April–May and September–October.

1. Plant in April–May or in September–October, preferably a container or rootballed plant. Never let the rootball dry out.
2. Dig a hole twice as wide as the rootball and just as deep. Loosen the sides with the spade.
3. Set the pine at the same depth as in its pot, with the root collar level with the soil.
4. Backfill, firm lightly and give it a generous watering.
5. Spread a little pine bark or wood chips around the base, not against the trunk.

Care

Water

In the first two summers, water generously once a week in dry weather. After that it manages on rain.

Feeding

Not needed in ordinary garden soil; too rich a diet gives long, soft shoots.

Mulching

A thin layer of pine bark or wood chips keeps the soil around young plants moister and weed-free.

Pinching candles

In May, pinch or cut the young shoots (candles) back by half for a dense, compact crown.

Old needles

In autumn the oldest needles turn brown and fall: this is normal. Pull them off by hand for a tidier look.

Tip: Pinch the new candles back by half every spring: the crown stays dense and compact and does not outgrow its place. Give it sun and dry, free-draining soil.

Japanese black pine: when to prune it?

Pruning months: May.

When: Only in May, while the young shoots (candles) are still soft and the needles have not yet opened.

How:

• Pinch or cut the new candles back by about half with sharp scissors, before the needles unfurl.
• Do this every year: it keeps the crown dense and stops it getting too big.
• Cut dead, crossing or damaged branches back to the trunk.

Caution: Never cut into bare, brown wood without needles or buds: a pine will not sprout again from it. Always leave some green.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Sow in March–April in a tray or pot of free-draining, sandy compost; keeping the seed moist in the fridge for a few weeks first helps. Seedlings grow slowly at first.

Buying

For shaped pines and special selections, buy a nursery plant: these are often grafted.

Japanese black pine: how does it get through the winter?

Hardy to −25 °C.

• Hardy to about −25 °C: no protection is needed in Flanders.
• Heavy, wet snow can break branches: shake it gently off.
• In a pot: put it in a sheltered spot, wrap the pot in hessian and water occasionally in dry, frost-free weather.

Diseases and pests

• Shoot dieback: Young shoots turn brown and curl, often after hail or a dry summer. Cut affected shoots back to healthy wood in dry weather and dispose of them.
• Woolly aphids: White, woolly patches on shoots and needles. Wash them off with a jet of water or dab them with soapy water.
• Wet feet: Yellow or brown needles and root rot on wet, heavy soil. Choose a dry, free-draining spot.
• Thin crown: If the crown becomes open and bare, it is too shady or has not been pinched. Give it full sun and pinch the candles every spring.

Through the year

• March: Remove dead branches. Sowing is possible from late March.
• April: Plant. Apply mulch.
• May: Plant. Pinch the young candles back by half.
• June: Water young trees in dry weather.
• July: Water young specimens. Watch for woolly aphids.
• August: Water during prolonged drought.
• September: Plant. Water regularly after planting.
• October: Plant. Pull out old, brown needles.
• November: Clear fallen needles. Protect pots from frost.
• December: Rest. Shake heavy snow off the branches.

Did you know?

• In Japan it is called kuromatsu, ‘black pine’. It is planted along the coast as a windbreak and to stabilise dunes.
• The species name honours Carl Peter Thunberg, the Swedish physician and botanist who collected plants in Japan in 1775–1776.
• It is often used as a rootstock for grafting other Japanese pines, such as the Japanese white pine.