Carex oshimensis

Carex oshimensis: how do you recognise it?

Habit

Low, rounded, arching clump about 30 cm tall and 40 cm wide.

Leaves

Narrow, linear and glossy; creamy yellow with green edges in ‘Evergold’, dark green with white edges in ‘Everest’.

Flowers

Inconspicuous brown spikes in April and May, among the leaves.

Stem

Three-sided, as in most sedges.

Roots

A fibrous clump that slowly widens without spreading invasively.

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

Why grow it?

• Evergreen: a fresh, striped clump all year, even in winter.
• Brightens dark spots in partial and full shade, where few foliage plants stay so colourful.
• Ideal in pots and containers, including a winter container on the patio.
• Compact and tidy: lovely as an edging along a path or at the front of a shady border.
• Grows on sand, loam and clay.
• Little work: just comb it out in spring.

Carex oshimensis: where does it grow best?

• Partial or full shade; in full sun the leaves can scorch and the plant dries out quickly.
• Humus-rich garden soil: sand, loam or clay, acid to chalky.
• Normally moist: it dislikes drying out, but also wet feet in winter.
• Lovely under shrubs and trees, along a shady path or in a pot by the front door.
• Allow 30–40 cm between plants; about 30 cm as an edging.

Light

Partial shade and shade

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Normal

Size

0.3 m tall, 0.4 m wide

Hardiness

Hardy (to -20 °C)

Goes well with

• Hosta: Large, rounded leaves beside the fine, striped foliage in shade.
• Ferns: Fine green fronds that make the yellow or white of the sedge stand out.
• Barrenwort: An evergreen ground cover with small spring flowers, in the same shade.
• Lungwort: Spotted leaves and blue or pink flowers in spring.
• Coral bells: Dark foliage as a contrast, in a pot or border.

Carex oshimensis: when and how to plant it?

Plant in March–May and September–October.

1. Plant in March–May or September–October.
2. Dig a hole twice as wide as the root ball and mix in compost or leaf mould.
3. Set the plant at the same depth as it was in the pot and firm the soil.
4. Leave 30–40 cm between plants.
5. In a pot: use good potting compost and a pot with a drainage hole.
6. Water generously straight away and keep the soil moist throughout the first summer.

Care

Watering

Water in dry spells, especially in the first years and in pots: drying out causes brown leaf tips.

Feeding

Some compost in April; in a pot, a little organic fertiliser in April and June.

Mulching

A layer of leaf mould in spring keeps the soil cool and moist.

Tidying

In March–April, comb dead and damaged leaves out of the clump.

Green shoots

In variegated cultivars, remove shoots with all-green leaves at the base.

Tip: Use ‘Evergold’ in dark corners and winter containers: its yellow-striped leaves light up places where few other plants give colour. Do water it in dry spells.

Carex oshimensis: when to prune it?

Pruning months: March–April.

When: It is not cut back. In March–April, simply comb out dead and damaged leaves.

How:

• Run gloved hands or a small rake through the clump to remove loose, dead leaves.
• If the clump looks untidy after a hard winter, cut off only the damaged leaves; new foliage soon covers the gap.
• Do not cut the clump down: it looks best if you only comb it out.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In April–May or September, lift a clump and split it into pieces with roots and a few shoots; replant straight away and water well. Cultivars such as ‘Evergold’ and ‘Everest’ do not come true from seed, so propagate them by division.

Carex oshimensis: how does it get through the winter?

Hardy to −20 °C.

• Hardy to about −20 °C: usually no problem in Belgian winters.
• The foliage stays attractive all winter; simply leave the clump standing.
• In a pot: in hard frost move it against a wall and wrap the pot; water occasionally in winter too if the compost is dry.
• It is a mainstay of winter containers, together with heather and ivy.

Diseases and pests

• Brown leaf tips: A sign of drought or too much sun. Water regularly and choose a shadier spot.
• Green leaves: Variegated cultivars sometimes produce all-green leaves. Remove them at the base.
• Root rot: In waterlogged soil the clump rots in winter. Make sure the soil drains well and do not leave pots standing in water.
• Bare centre: Old clumps go bare in the middle. Divide them in spring.

Through the year

• January: Evergreen foliage. Protect pots in hard frost.
• March: Comb out dead leaves. Plant.
• April: Inconspicuous flowers. Add compost and comb out the last dead leaves.
• May: Plant or divide. Mulch.
• June: Water in dry spells, especially in pots.
• July: Water in dry spells.
• August: Water in dry spells.
• September: Plant or divide.
• October: Plant. Use in winter containers.
• December: Fresh foliage in the winter garden.

Did you know?

• The species name oshimensis refers to Ōshima, a Japanese island.
• ‘Evergold’ was long sold under other names, such as Carex hachijoensis or Carex morrowii ‘Evergold’, before it was placed in Carex oshimensis.
• Because it keeps its colour even in frost, it is one of the most widely used plants in winter containers.