Photo: Daderot, Public domain · source
Ornamental grass · Cyperaceae
Broad-leaved sedge
Carex siderosticta
In other languages: Carex siderosticta (Nederlands) · Carex siderosticta (Français)
Carex siderosticta is a sedge from the forests of Japan, Korea and north-east China. It has strikingly broad, soft leaves about 3–4 cm wide, so it looks more like a small hosta than an ordinary ornamental grass. The plant spreads slowly by underground runners and over the years forms a loose carpet 25 cm tall. The best-known cultivar is ‘Variegata’, with a white edge to the leaf. In April–May small flower spikes appear, before the new leaves have fully unfurled. In winter the foliage dies back.
Light
Partial shade or shade
tolerates little sun
Moisture
Normal
no wet feet
Legal basis
Loam or peat
acid to neutral
Hardiness
Fully hardy
down to -25 °C
Size
0.25 m
tall, 0.4 m wide
Flowering
April–May
| Pruning months | February |
|---|---|
| Height | 0.25 m |
| Native to Belgium | No, planted |
| Poisonous to people and pets | Not known to be poisonous |
| Flowering | April–May |
Identify
Broad-leaved sedge: how do you recognise it?
- Habit
- Low, slowly spreading clumps 25 cm tall and 30–40 cm wide, merging into a carpet.
- Leaves
- Broad, up to about 4 cm, soft and fresh green; with a white edge in ‘Variegata’. Dies back in winter.
- Flowers
- Small, discreet spikes close to the ground in April–May, often before the foliage is fully grown.
- Seed
- Small nutlets in the spikes, ripe in summer.
- Roots
- Creeping rhizomes with which the plant slowly spreads.
Flowering: April–May · Plants: March–May and September–October · Pruning: February
In your garden
Why grow it?
- Broad, hosta-like leaves bring a light, fresh colour to the shade.
- The white-edged leaves of ‘Variegata’ light up a dark corner.
- A calm ground cover for under trees and shrubs, slowly forming a carpet.
- Flowers early, in April–May.
- Little work: no feeding, no pruning, just clear away old leaves in February.
Broad-leaved sedge: where does it grow best?
- Part shade to light shade; in full sun the leaves scorch.
- Humus-rich, moisture-retentive soil: loam or peaty soil, acid to neutral.
- Sheltered and cool, for example under trees or on the north side of a wall.
- Allow 25–30 cm between plants if you want a carpet; they slowly grow together.
- Light
- Partial shade and shade
- Soil type
- Loam or peat
- Acidity
- Acid or neutral
- Moisture
- Normal
- Size
- 0.25 m tall, 0.4 m wide
- Hardiness
- Hardy (to -25 °C)
Goes well with
- Hosta: The same part shade; the sedge looks a little like a small hosta.
- Ferns: Fresh green underplanting with finer foliage.
- Barrenwort: A carpet of leaves and small flowers under the same trees.
- Hellebore: Flowers in winter and is evergreen too.
- Lungwort: Spotted leaves and blue and pink flowers in early spring.
Maintenance
Broad-leaved sedge: when and how to plant it?
Plant in March–May and September–October.
- Plant in March–May or September–October, when the soil is neither frozen nor waterlogged.
- Dig a hole twice as wide as the root ball and mix in plenty of leaf mould.
- Set the plant at the same depth as in its pot, with the top of the root ball at soil level.
- Firm the soil and water in generously straight away.
- Spread leaf mould around the plants and keep the soil moist in the first year.
Care
- Water
- Keep the soil moist. In dry weather water generously, especially in the first year; the leaves dry out quickly.
- Feeding
- A layer of compost or leaf mould in spring is enough.
- Mulching
- Leaf mould in autumn keeps the soil cool and moist and suppresses weeds.
- Tidying
- Cut off the dead foliage in late February, before the new leaves and flower spikes come through.
- Weeding
- Weed by hand between young plants, carefully; once they form a carpet they smother weeds themselves.
Tip: Cut off the dead foliage in late February, before the new leaves and flower spikes come through: that shows off the fresh white-edged foliage at its best.
Broad-leaved sedge: when to prune it?
Pruning months: February.
When: Late February, before the new shoots and flower spikes come through.
How:
- Cut all brown, dead leaves off just above the ground.
- Do this before the new leaves emerge so that you do not damage them.
- No further pruning is needed.
Propagation
- Division
- In March–April, when the plant starts into growth, cut off a piece with rhizome and roots with a sharp spade and replant at once. Water well.
- Seed
- Sow fresh seed in summer in pots of damp soil and keep them cool. Germination is slow; division is much quicker.
Broad-leaved sedge: how does it get through the winter?
Hardy to −25 °C.
- Hardy down to about −25 °C: no protection is needed in Flanders.
- The foliage dies back in winter; the rhizomes survive in the soil. Cut it off in late February.
- In a pot: stand it against a wall and wrap the pot in hessian so the roots do not freeze.
Diseases and pests
- Brown leaf edges: Caused by drought or too much sun. Water more and choose a shadier spot.
- Slugs: Young leaves are sometimes nibbled in spring. Look for them in the evening and remove them by hand.
- Soil too dry: The plant sulks or does not grow. Work in compost and mulch.
- Root rot: In wet, heavy clay the roots can rot in winter. Plant in a well-drained spot or work in compost and a little sand.
Through the year
- February: Cut off dead foliage before the new foliage comes through.
- March: Plant or divide. Apply compost.
- April: Flowering. Plant.
- May: New leaves unfurl. Plant. Water in dry spells.
- June: Water in dry spells.
- July: Water in dry spells. Seed ripens.
- August: Water in dry spells.
- September: Plant.
- October: Plant. Mulch with leaf mould.
- November: The foliage dies back.
You and this species
Did you know?
- The plant looks like a hosta, whereas most sedges have narrow, grass-like leaves.
- It grows slowly: in the same spot it forms an ever denser carpet over the years.
- The genus Carex has more than 2,000 species and is one of the largest plant genera.