How to Grow Japanese Sedge

Japanese sedge grass (carex morrowii)

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Japanese Sedge (Carex morrowii) is also known as Kan suge or Marrow's Sedge. Hardy in USDA Zones 5b to 9a, this semi-deciduous rhizomatous evergreen is native to Central and Southern Japan. It forms a densely tufted tussock of slender foliage that shimmers in the breeze.

The growth habit of this grassy plant is tidy, dense, clumping and mounding. Flat, thick, dark green leaves are 12 inches wide and 1/4 to 1/2 inch wide. Fleeting spikes have four to six small copper-brown flowers in mid to late spring, and each flower is comprised of four to five petals. These plants develop at a moderate growth rate, achieving a maximum size of 12 to 18 inches tall and 18 to 24 inches wide in a few years.

Mingling attractively with flowering bulbs and perennials, this sedge is very versatile and great for creating textured landscapes. It can be used amongst beds and borders and is excellent for growing around ponds or water gardens. As well as growing well in containers, it also looks good in rock and cottage gardens, and it will grow well beneath trees and shrubs.

Mass plantings will attract many butterflies and pollinators. This plant also supports various Satyr larvae.

Botanical Name

Carex morrowii

Common Names

Japanese Sedge, Kan suge, Marrow's Sedge, Variegated Sedge

Plant Type  Semi-deciduous rhizomatous evergreen
Mature Size 12 to 18 inches tall and 18 to 24 inches wide
Sun Exposure Dappled sunlight to full shade
Soil Type Adaptable (Chalk, Clay, Loam, Sand)
Soil pH Acid, Alkaline, Neutral
Bloom Time Mid to late spring
Flower Color Brown or copper
Hardiness Zones 5b, 6, 7, 8, 9a
Native Area Central to Southern Japan

Japanese Sedge Care

Like tussock and foothill sedges, the Japanese variety is also deer tolerant and low-maintenance, offering nearly year-round interest where it is winter hardy.

Light

Able to brighten shady areas, Japanese Sedge thrives in dappled sunlight to full shade. The foliage may bleach in full sun.

Soil

Establish Japanese sedge in any moderately moist, fertile, well-draining soil. This plant adapts to a variety of soils from chalk, clay, loam, and sand. It isn't particular about pH levels, but it isn't keen on dry soil.

Water

When the top of the soil is dry to the touch, water occasionally to allow roots to spread and establish. As the roots reach for moisture in the drying soil, they will become stronger. Once established, the plant is drought-tolerant for brief stretches.

Temperature and Humidity

Cover with a thick layer of organic mulch around the root zone in northern regions to protect from colder temperatures and harsher winds.

Is Japanese Sedge toxic?

The little research available shows that the Japanese Sedge is not toxic. As always, be cautious and be mindful of any symptoms that may occur if you or a pet should come into contact with any unfamiliar plant.

Pruning

It is not necessary to prune your Japanese sedge, but doing so in late winter to very early spring will welcome fresher foliage in mid-spring.

If the location does not permit the plant to offer winter interest year-round, cut the foliage to the ground and remove it from the site in late winter.

Propagating Japanese Sedge

Division is the recommended means of propagation when, every two or three years, the centers of the plant will probably stop producing new leaves. Divide in spring. Plant each individual clump separately.

Japanese Sedge Varieties

Evergold, Gold Band, Ice Dance, Silk Tassel, and Variegata are cultivars of Japanese Sedge. Bright yellow Gold Band has accented leaves that add cheery color to darker, shadier areas.

Carex morrowii 'Variegata' produces blades with white leaf margins. Some selections offer gold bands and silver stripes.

Related Plants

More than 1500 species of Carex grow in moist to wet areas around the world, making it challenging to identify individual species.

Along with the foothill and tussock sedges, there are a variety of other common grass types in the Carex genus that are sometimes confused with Japanese sedge and can grow in the same regions. These include silvery sedge, shallow sedge, awl-fruited sedge, and the blunt broom sedge.

Pests/Diseases 

Avoid extreme drought or very sodden soils that could negatively impact the health of Japanese Sedge. Overall though, pest or disease issues are rare. This plant is easy to care for and very versatile.