Acorus Species, Japanese Rush, Golden Japanese Sweet Flag, Grassy-leaved Sweet Flag

Acorus gramineus

Family: Acoraceae
Genus: Acorus (AK-or-us) (Info)
Species: gramineus (gram-IN-ee-us) (Info)
Synonym:Acorus gramineus var. japonicus
Synonym:Acorus humilis
Synonym:Acorus macrospadiceus
Synonym:Acorus pusillus
Synonym:Acorus xiangyeus




Ponds and Aquatics

Water Requirements:

Average Water Needs; Water regularly; do not overwater

Requires consistently moist soil; do not let dry out between waterings

Sun Exposure:

Sun to Partial Shade


Grown for foliage


Good Fall Color

Provides Winter Interest

Foliage Color:



12-18 in. (30-45 cm)


6-9 in. (15-22 cm)


USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

USDA Zone 10a: to -1.1 C (30 F)

USDA Zone 10b: to 1.7 C (35 F)

Where to Grow:

Unknown - Tell us


Unknown - Tell us

Bloom Color:

Pale Green


Bloom Characteristics:

Unknown - Tell us

Bloom Size:

Unknown - Tell us

Bloom Time:

Mid Summer

Late Summer/Early Fall

Other details:

Unknown - Tell us

Soil pH requirements:

Unknown - Tell us

Patent Information:


Propagation Methods:

By dividing rhizomes, tubers, corms or bulbs (including offsets)

Seed Collecting:

Unknown - Tell us


This plant is said to grow outdoors in the following regions:

Folsom, California

Marietta, Georgia

Wilkes Barre, Pennsylvania

Missouri City, Texas

Bellingham, Washington

Gardeners' Notes:


On Jun 15, 2010, hmbgerl from Folsom, CA wrote:

I divided into two before planting. In less than a year, both sections have doubled and I'm ready to divide again. It's a nice contrast near rocks or dark foliage and it looks good against mulch. I have the dwarf species so it is compact and doesn't take over my garden.


On Jan 16, 2005, mgarr from Hanover Twp., PA (Zone 6a) wrote:

I know that this plant should have moisture but thank goodness plants can't read what we write about them. Mine is in part sun growing under an oak tree along the sidewalk. I give it no extra water and it has done fine in this spot for three years now.


On Mar 5, 2002, Dynamo wrote:

One of the most striking and certainly the cutest of the sweet flags, this dwarf golden form makes a slowly spreading tuft of tiny golden evergreen grass-like foliage. A. 'Minimus Aureus' makes a bright little groundcover in moist areas or a feature between stepping stones... a real highlight in the woodland garden.


On Aug 31, 2001, smiln32 from Oklahoma City, OK (Zone 7a) wrote:

Easily grown in average, medium wet to wet soils in full sun to part shade. Grows well in both boggy conditions (including very shallow water) and consistently moist garden soils. Scorched leaf tips will occur if soils are allowed to dry out. Appreciates some relief from hot summer sun (e.g., afternoon shade or filtered sun) when grown in hot summer climates. Slowly naturalizes by spreading roots, but is not invasive. May not be reliably winter hardy in the northern areas of USDA Zone 5. Evergreen in warm winter climates.


On May 25, 2001, jody from MD &, VA (Zone 7b) wrote:

There are only 2 species in this genus of grass like evergreen perennials from stream banks and marshes in the northern hemispere.

This species is native to Janpan and has soft, curved leaves under 12" long and about 1/4" wide. The flowers spikes are about 1" long and appear in spring and summer. Sweet flags are easily grown in any boggy spot or in shallow water at pond edges. They need no maintenance except for cutting back to limit their spread.