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Grassy-Leaved Sweet Flag

Acorus gramineus (AH-kor-us gram-IN-ee-us)

Family: Acoraceae Non-native Herbaceous (1-3 ft)

Japanesse sweetflag is a flowering monocot in the the s weetflag family (Acoraceae) native to Japan, Korea and eastern Asia. The Genus name comes from the Greek word acoron, which means "pupil". The specific epithet comes from the Latin word meaning grass referring to its grass-like appearance.. The clump-forming plant grows up to 1 foot tall and spreads by rhizomes to form a ground cover. It grows in partially submerged conditions or very wet soils in full sun to partial shade. In hot summer areas, it will do best with some afternoon shade. Plant 8 to 12 inches apart to allow room to spread. The spring flowers are insignificant and are followed by small berries. The plant is grown for its long and narrow leaves and grass-like appearance. Plant along streams, bogs, ponds, in wet woodlands, and along water banks, It can be used for an edging groundcover or in a container if the soil is kept moist. Insect, Disease, or Other Plant Problems: No significant problems. However, if soils are dry, issues can arise (such as leaf scorching).

Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 51 attributes.

How it fits the guild

Guild layer 4 - Herbaceous (1-3 ft) Optimal soil pH Acid (<6.0); Neutral (6.0-8.0)
See companions & conflicts ↓

Companions & Conflicts

Curated pairwise relationships between this plant and others in the library — who feeds whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.

No curated interactions recorded for this species yet.

Also noted by NC State

Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.

Fills a similar niche Canna Carex cherokeensis Saururus cernuus
Similar, less problematic Acorus americanus

Full plant profile

Growing Conditions
Plant type
Ground Cover; Herbaceous Perennial
Life cycle
Perennial
USDA zones
6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
Light
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; Loam (Silt); Sand
Soil pH
Acid (<6.0); Neutral (6.0-8.0)
Soil drainage
Frequent Standing Water | Occasionally Wet
Available space
Less than 12 inches
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 0 ft. 6 in. - 1 ft. 0 in. | Width: 0 ft. 6 in. - 1 ft. 0 in.
Growth rate
Medium
Maintenance
High
Canopy layer
4 - Herbaceous (1-3 ft)
Form & Appearance
Habit / form
Arching; Dense; Erect
Texture
Fine
Leaf color
Green
Leaf shape
Linear
Leaf margin
Entire
Leaf feel
Glossy
Leaf value
Fragrant
Leaf size
> 6 inches long, < 1 inch wide
Hairs present
No
Leaf detail
Green leaves are 1/4 inch wide, 6-18 inches long, narrow, linear, shiny/glossy, erect and smell sweet when crushed.
Flower color
Gold/Yellow; Green; Insignificant
Flower form
Spike
Flower size
3-6 inches
Flower detail
These small, lateral flowers are green and yellow, blooming in mid-spring/ summer (around May to June) on a spike that is up to 4 inches long
Bloom time
Spring; Summer
Fruit color
Red/Burgundy
Fruit type
Berry
Fruit size
< 1 inch long, < 1 inch wide
Fruit detail
After flowers bloom, small red fleshy berries appear.
Wildlife & Ecology
Native status
Non-native
Origin
Japan, Korea and eastern Asia
Food & Medicine
Fruit type
Berry
Landscape Use
Landscape location
Container; Naturalized Area; Riparian; Slope/Bank; Small Space; Woodland
Landscape theme
Rain Garden; Water Garden
Design feature
Accent; Border; Mass Planting
Garden tags
#evergreen #yellow flowers #full sun tolerant #small spaces #groundcover #spring interest #HS302 #partial shade tolerant #container plant #th-smell #HS303 #stream banks #wet soils tolerant #riparian #semi-evergreen #boggy sites #pond
Problems & Resistance
Resistant to
Erosion; Wet Soil
Particularly resistant to
erosion, wet soil

Planted at Hunnicutt

Nobody’s planted this one yet.