Japanese blood grass

Japanese blood grass: how do you recognise it?

Habit

Loose, upright clump 30–40 cm tall and about 30 cm wide, spreading slowly by underground runners.

Leaves

Flat, narrow and stiffly upright, with a rough edge. Green at the base, wine red towards the tip.

Colour

The red starts at the tips and moves down during the summer. In autumn the whole clump is coppery red to deep red.

Flowers

It rarely flowers in our climate. In warm regions it produces narrow, fluffy, silvery-white flower spikes.

Roots

Underground rhizomes: slow in the red cultivar, far more vigorous in green shoots that have reverted.

Plants: April–May · Pruning: March–April

Why grow it?

• One of the most brightly coloured grasses: deep red foliage from summer into autumn.
• Stunning when backlit, for example by low morning or evening sun.
• Stays low and compact, ideal for the front of a border or a pot.
• Little work: one cut in spring and some water in dry spells.
• A strong contrast with grey, silver and blue foliage in a gravel garden.

Japanese blood grass: where does it grow best?

• Full sun or light partial shade. The more sun, the brighter the red; in shade it stays greener.
• Well-drained sandy or loamy soil, acid to neutral, that does not dry out in summer.
• Avoid heavy, wet ground: in winter the roots rot in waterlogged soil.
• Choose a spot where light comes from the side or from behind: that shows the colour best.
• Allow 30 cm between plants. A group of five or more makes the biggest impact.

Light

Sun and partial shade

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Normal

Size

0.4 m tall, 0.3 m wide

Hardiness

Hardy (to -15 °C)

Goes well with

• Blue fescue: A fine, blue-grey grass as a cool contrast to the red.
• Stonecrop: Fleshy leaves and late flowers for the same sunny, well-drained spot.
• Lamb’s ears: Soft, silvery-grey leaves at the foot of the red grass.
• Heuchera: Dark or orange-red foliage that echoes the red tones.

Japanese blood grass: when and how to plant it?

Plant in April–May.

1. Plant in April or May, once the soil has warmed up, so it roots in well before winter.
2. Dig a hole twice as wide as the pot and lighten heavy soil with some grit or fine gravel.
3. Set the clump at the same depth as it was in the pot and firm the soil lightly.
4. Space plants 30 cm apart, preferably in small groups.
5. Water in straight away and keep the soil moist for the first few weeks. A thin layer of compost around the base helps.

Care

Water

Water in dry spells, especially in the first year and in pots. Do not let the soil stay dry for long, but do not let it stay wet either.

Feeding

Hardly needed: a little compost in spring is enough.

Green shoots

Watch all season for entirely green shoots and dig them out at once, roots and all.

Mulching

A thin layer of compost in spring; in a gravel garden the gravel serves as mulch.

Pots

Use potting compost with some sand for good drainage. Repot every two or three years.

Tip: Plant it where the morning or evening sun shines through it from behind: the red leaves then seem to glow. Each time you walk round the garden, check quickly for green shoots.

Japanese blood grass: when to prune it?

Pruning months: March–April.

When: In March–April, once the worst frosts are over and before the new leaves appear.

How:

• Cut the old, faded foliage back to just above the ground.
• Leave the old foliage over winter: it protects the crown from cold and wet.
• Remove green shoots as soon as you see them, even in summer, and dig out the rhizome with them.

Caution: Green shoots have reverted to the wild form. They grow much more strongly than the red leaves, can take over the clump and start to spread.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In May–June, once new growth is well under way: take a rooted piece from the edge of the clump and replant it at once. Only use pieces that are completely red.

Japanese blood grass: how does it get through the winter?

Hardy to −15 °C: protect young plants.

• Moderately hardy, to about −15 °C. It survives an ordinary Belgian winter outdoors.
• Leave the old foliage standing and cover the clump with a layer of dry leaves or straw in severe winters.
• Wet soil in winter is more dangerous than frost: plant in soil that drains well.
• In winter, move a pot against a sheltered wall, out of the rain, or into an unheated shed.

Diseases and pests

• Reversion to green: Entirely green shoots among the red leaves. Dig them out at once, roots and all, or they will take over the plant and spread.
• Root rot: The clump fails to sprout in spring or turns soft at the base. The cause is wet soil in winter: replant in a better-drained spot.
• Little red: Too much shade. Move it to a sunnier spot.
• Late start: It comes into growth late in spring, often in May. That is normal: do not dig it up too soon.

Through the year

• March: Cut old foliage back to just above the ground.
• April: Plant. Cut back if not done yet.
• May: Plant. New shoots appear; remove any green ones at once.
• June: Divide. Water in dry spells.
• July: The red moves further down the leaves. Dig out green shoots.
• August: Water in dry spells, especially pots.
• September: Full colour, at its best when backlit.
• October: Coppery red autumn colour.
• November: Leave the foliage. Move pots to a sheltered spot.
• December: In hard frost, cover with leaves or straw.

Did you know?

• In warm regions the wild green form is regarded as one of the worst weeds in the world. Fortunately the red cultivar grows much more slowly.
• In the south-eastern United States the wild form is a notorious invasive plant that overruns large areas.
• The species name cylindrica refers to the narrow, cylindrical flower spike.