Pennsylvania sedge

Pennsylvania sedge: how do you recognise it?

Habit

Low mat 15–25 cm tall and 30 cm per plant, slowly spreading.

Leaves

Very narrow and fine, 1–3 mm wide, arching; bright green, largely green in mild winters.

Flower

Modest yellow to brown spikes in April–May, often barely visible among the leaves.

Fruit

Small fruits formed after flowering in spring.

Roots

Thin, creeping rhizomes that extend the mat.

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

Why grow it?

• A green, lawn-like carpet in dry shade under trees, where grass will not grow.
• Drought tolerant and suited to poor, acid soil.
• Needs very little maintenance: at most one mow or trim a year.
• Soft, fine foliage that ripples prettily in the wind.
• Suppresses weeds once the mat has closed.

Pennsylvania sedge: where does it grow best?

• Half shade to shade; it does very well under trees and in dry shade.
• Dry to normal, well-drained soil: sand or loam, acid to neutral. It does less well on chalky soil.
• Tolerates drought well once established, but not lasting wet soil.
• Plant 25–30 cm apart for a closed mat within two to three years.

Light

Partial shade and shade

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Dry or normal

Size

0.2 m tall, 0.3 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Snowdrop: Flowers in winter through the green carpet.
• Hardy cyclamen: Flowers in autumn in dry shade.
• Bluebell: A spring bulb for the same shady spots.
• Barrenwort: A low, elegant ground cover for dry shade.

Pennsylvania sedge: when and how to plant it?

Plant in March–May and September–October.

1. Plant in March–May or in September–October, when the soil is not frozen.
2. Clear the soil of weeds and work some leaf mould into poor sandy soil.
3. Set the plants at the same depth as in their pots and firm the soil well.
4. Plant 25–30 cm apart; for faster cover you can plant closer.
5. Water thoroughly straight away and keep the soil moist during the first season.
6. Leave fallen leaves in place or spread a thin layer of leaf mould; keep weeds down in the first years.

Care

Water

Regularly in the first season; after that only during long dry spells.

Feeding

Usually not needed; on very poor soil a thin layer of compost in spring.

Weeding

Especially in the first two years, until the mat has closed.

Mowing

Once a year in early spring, with the mower on its highest setting.

Foot traffic

Tolerates occasional walking, but not heavy use such as a play lawn.

Tip: Plant it 25–30 cm apart under trees and mow it at most once a year on the highest setting: you get a green mat in dry shade.

Pennsylvania sedge: when to prune it?

Pruning months: March.

When: March, in early spring before the new growth.

How:

• Mow the mat once a year on the highest setting (6–8 cm).
• On small areas you can trim the old foliage with shears.
• Rake away the cut foliage so the new shoots get light.
• Mowing is not essential; it only keeps the carpet tidier.

Caution: Do not mow too short: cutting too low weakens the mat.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In spring or in September cut pieces of the mat with rhizomes and replant them elsewhere; water straight away.

Seed

Germination is slow and uneven; division is much quicker and more reliable.

Pennsylvania sedge: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: no protection needed.
• The foliage stays largely green in mild winters and turns brown in severe frost; new growth follows in spring.
• In a pot: keep the compost moist and place the pot against a wall.

Diseases and pests

• Weeds in the mat: Especially in the first years, while the mat has not yet closed. Weed regularly and plant a little closer.
• Brown, withered foliage: After strong sun, long drought or severe frost. Water and mow in spring; new shoots follow.
• Bare patches: From too much foot traffic or too much shade. Limit walking and plant young divisions in the gaps.
• Rot in wet soil: On heavy, wet clay the mat dwindles. Choose a free-draining, drier spot.

Through the year

• March: Mow or trim. Plant. Divide.
• April: Flowering. Plant.
• May: Flowering. Plant. Weed.
• June: Weed. Water in dry spells in the first year.
• September: Plant or divide.
• October: Plant. Leave fallen leaves.
• December: Rest.

Did you know?

• The species name pensylvanica is spelled with one n. That is the original botanical spelling.
• In North America it is often used as a lawn alternative in shade.
• In the wild it often grows in dry, open oak woods.