Purple moor grass

Purple moor grass: how do you recognise it?

Habit

Dense, upright clump; leaves 30–50 cm tall, up to 90 cm with the flower stems. About 50 cm wide.

Leaves

Narrow, linear and fresh green; ‘Variegata’ has cream-striped leaves.

Flowers

Narrow, purplish panicles on long, straight stems, from July to September.

Autumn colour

Stems and leaves turn golden yellow to ochre.

Stems

Almost without nodes; in winter they snap off at the base by themselves.

Roots

Dense and fibrous; no spreading runners.

Flowering: July–September · Plants: March–May · Pruning: March

Why grow it?

• A native grass that fits perfectly in a wildlife garden or heather garden.
• Airy stems you can look through: ideal at the front of a border or among perennials.
• Glorious golden autumn colour from September into November.
• Grows on damp, acid soil where many other ornamental grasses struggle.
• Food plant for the caterpillars of some native butterflies, including the chequered skipper.
• Little work: the stems break off by themselves in winter.

Purple moor grass: where does it grow best?

• Sun or partial shade; in deep shade it flowers less and the stems flop.
• Acid to neutral soil: sand, loam or peat. It dislikes chalky soil.
• Moist to wet soil, even at a pond edge. On dry sandy soil, water in summer.
• Allow 40–50 cm between plants; it looks best in groups of three to five.

Light

Sun and partial shade

Soil type

Sand, loam or peat

Acidity

Acid or neutral

Moisture

Normal or wet

Size

0.9 m tall, 0.5 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Heather: Together they create a heathland scene, on the same acid soil.
• Cross-leaved heath: Pink bells in summer, on wet, acid soil.
• Purple loosestrife: Purple-pink spikes among the airy stems, on moist soil.
• Hemp agrimony: Large, dusky pink flower heads for bees and butterflies, in the same damp spot.
• Great burnet: Dark red bobbles poking through the stems.

Purple moor grass: when and how to plant it?

Plant in March–May.

1. Plant in spring, from March to May: it roots best in warming soil. Autumn planting is less successful.
2. Dig a hole twice as wide as the pot and loosen the soil well.
3. On sandy soil, mix some leaf mould into the planting soil.
4. Set the plant at the same depth as in the pot: do not bury the crown.
5. Water thoroughly and keep the soil moist during the first year.
6. A thin layer of leaf mould around the plant keeps the soil cool and moist.

Care

Watering

Regularly in dry spells during the first year. After that only in dry summers on sandy soil.

Feeding

Not needed: on rich soil the stems flop. A little leaf mould in spring is enough.

Tidying

In winter rake up the broken stems and in March cut off the last dead leaves.

Patience

It only starts growing in April and takes two to three years to form a full clump.

Dividing

Rarely needed; only when the centre of the clump becomes bare, in spring.

Tip: Leave the stems standing in autumn for their golden colour; they break off at the base by themselves in winter. Plant it on damp, acid soil and do not feed it.

Purple moor grass: when to prune it?

Pruning months: March.

When: Hardly any pruning is needed: the stems break off by themselves in winter. In March tidy up the rest before the new leaves appear.

How:

• In winter gather or rake up the loose stems; they snap off at the base on their own.
• In March cut the remaining dead leaves back to 5–10 cm above the ground.
• Work carefully so you do not damage the heart of the clump.
• Put the dry stems on the compost heap.

Caution: Do not cut back in autumn: that is exactly when the golden stems look their best.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In April–May, as the new leaves appear: slice pieces off the clump with a sharp spade and replant them at once. Keep them well watered.

Self-sown seedlings

The species sometimes self-seeds on damp soil; move the seedlings in spring. Cultivars do not come true from seed.

Purple moor grass: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: no protection is needed in Belgium.
• The golden stems stay upright into early winter and then snap off at the base.
• In a pot: keep the compost slightly moist, even in winter, and stand the pot in a sheltered spot against a wall.

Diseases and pests

• Late start: In March the clump looks dead. Don’t panic: purple moor grass only starts growing in April. So do not dig it up.
• Flopping stems: Too much shade or too rich a soil makes the stems weak. Do not feed and choose a sunnier spot.
• Brown leaf tips: A sign of drought, especially on sandy soil in full sun. Water well and mulch.
• Seedlings: On damp soil the species sometimes self-seeds. Pull up unwanted seedlings while young.

Through the year

• January: Rest. Rake up broken stems.
• February: Rest. Clear fallen stems.
• March: Cut dead leaves back to 5–10 cm. Plant.
• April: New leaves appear. Plant or divide.
• May: Plant or divide. Mulch with leaf mould.
• June: Growth. Water young plants in dry spells.
• July: The first flower spikes appear.
• August: Flowering. Water on dry sandy soil.
• September: Flowering. The spikes turn yellow.
• October: Golden autumn colour.
• November: Leave the stems; they start to break off.
• December: Clear the broken stems.

Did you know?

• Its Dutch name, ‘pijpenstrootje’ (little pipe straw), comes from the old use of its long, knotless stems to clean tobacco pipes.
• The genus is named after the Chilean priest and naturalist Juan Ignacio Molina.
• On many Flemish heaths purple moor grass is spreading because of nitrogen from the air; nature managers mow or strip the turf to keep the heath open.