Carex, Genus, oshimensis, Species,
- Genus & species
Japanese sedge
Overview
Carex oshimensis is an evergreen, clumping, grass-like perennial in the family Cyperaceae, native to Japan. Plants form arching mounds 12–18 inches (30–45 cm) tall and 18–24 inches (45–60 cm) wide. Leaves are narrow, 0.25 inch (6 mm) wide and 12–18 inches (30–45 cm) long, dark green, and arch outward from the crown. Stems are triangular in cross-section, as in most sedges. Flowers are borne in inconspicuous brown spikelets 1–2 inches (2.5–5 cm) long that rise to or slightly above the foliage in April and May, with male and female spikelets on the same stem. Fruit is a small, three-angled achene enclosed in a papery sac. Plants are hardy in USDA zones 6–9 and spread slowly by short rhizomes. Growth is slow, and foliage browns at the tips in hot, dry conditions and in exposed winter sites. Several variegated cultivars, including C. oshimensis 'Evergold', have cream-striped leaves.
Native Range
Native to Japan, where it grows on coastal slopes and in forest understory in the warm-temperate zone. Grown in temperate gardens outside its native range.Suggested Uses
Used as a ground cover, edging, and in shaded borders and containers, spaced 12–18 inches (30–45 cm) apart. Evergreen foliage remains in place through winter in zones 6–9. Slow spread limits use for rapid ground cover.How to Identify
Appearance
Size & Dimensions
Height1' - 1'6"
Width/Spread1'6" - 2'
Bloom Information
Flowers open in April and May as brown spikelets at or slightly above the foliage. Male and female spikelets are borne on the same stem, and pollination is by wind. Achenes ripen in early summer. Flowers are inconspicuous relative to the foliage mound.
Detailed Descriptions
Foliage Description
Dark greenGrowing Conditions
Sun Requirements
Requires 2-6 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Growth is steadiest in part shade to full shade in moist, well-drained soil of pH 5.5–7.0 that is high in organic matter. Full sun is tolerated where soil moisture is maintained, and leaf tips brown in hot afternoon sun. Water is applied at 1 inch (2.5 cm) per week during the first growing season, and established plants tolerate short dry periods. Cold hardiness is USDA zones 6–9. Clumps are divided in spring every 3–4 years, and slugs occasionally feed on new growth.Pruning
Old and damaged foliage is cut to 2–3 inches (5–8 cm) above ground in early spring, before new growth emerges. Foliage is otherwise left in place through winter. Dead leaf blades are removed by combing through the clump with gloved fingers at any time. Plants regrow within 4–6 weeks after cutting.Pruning Schedule
Prune: February–March
early spring
Container Growing
Suitable for container growing
Minimum container size: 1 gallons
