Acorus, Grassy-Leaved Sweet Flag, Japanese Rush, Japanese Sweet Flag 'Ogon'

Acorus gramineus

Family: Acoraceae
Genus: Acorus (AK-or-us) (Info)
Species: gramineus (gram-IN-ee-us) (Info)
Cultivar: Ogon




Ponds and Aquatics

Water Requirements:

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

Very high moisture needs; suitable for bogs and water gardens

Sun Exposure:

Partial to Full Shade


Grown for foliage


Good Fall Color


Foliage Color:

Unknown - Tell us


6-12 in. (15-30 cm)


9-12 in. (22-30 cm)


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)

Where to Grow:

Grow outdoors year-round in hardiness zone

Can be grown as an annual


All parts of plant are poisonous if ingested

Bloom Color:



Bloom Characteristics:

Unknown - Tell us

Bloom Size:

Unknown - Tell us

Bloom Time:

Late Spring/Early Summer

Other details:

Unknown - Tell us

Soil pH requirements:

5.6 to 6.0 (acidic)

6.1 to 6.5 (mildly acidic)

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:

Birmingham, Alabama

Eclectic, Alabama

Tuscaloosa, Alabama

Castro Valley, California

Clayton, California

NORTH FORK, California

San Bernardino, California

San Leandro, California

Denver, Colorado

Lula, Georgia

Chicago, Illinois

Ewing, Kentucky

Annapolis, Maryland

Roslindale, Massachusetts

Pass Christian, Mississippi

Fishkill, New York

Elizabeth City, North Carolina

Chesterland, Ohio

Cincinnati, Ohio

Cleveland, Ohio

Portland, Oregon

North East, Pennsylvania

Florence, South Carolina

Arlington, Texas

Fort Worth, Texas

Mansfield, Texas

Rowlett, Texas

Ogden, Utah

Leesburg, Virginia

Lexington, Virginia

Mc Lean, Virginia

Kirkland, Washington

Langley, Washington

Puyallup, Washington

Vancouver, Washington

show all

Gardeners' Notes:


On Jan 21, 2014, coriaceous from ROSLINDALE, MA wrote:

A beautiful, easy, evergreen foliage plant. The chartreuse variegated leaf blades glow. Clump-forming.

We've used this to edge an irrigated rose garden in Massachusetts Z6a. Clumps are quick growing where happy, but not aggressive. Requires consistent moisture to keep leaf tips from browning, but it doesn't require wet soil, and it does well in full sun as long as it never gets too dry at the root,

This was used in traditional herbal medicine, but is both toxic and carcinogenic if ingested.

Easily propagated by division.

Armitage says this is hardy in Z5.


On Nov 10, 2009, Biker1 from McLean, VA (Zone 7a) wrote:

I planted this on the bank of a stream leading into a pond. It makes a nice, low, glowing focal point. It is also a very dense clump that prevents erosion and weeds.


On Dec 16, 2005, hanna1 from Castro Valley, CA (Zone 9a) wrote:

Growing well in a full sun or light shade area. Great along pathways and borders, can also be used for accent planting in a rockery. It's strap-like leaves emit a sweet scent when bruised or crushed. Needs good air circulation. Keep plant constantly moist to avoid the leaves developing burnt tips.


On Apr 29, 2005, Shadyfolks from Chesterland, OH (Zone 5b) wrote:

I have to agree, this is a great plant. It will live in an area that is not constantly wet, but if you want it to thrive and grow make sure it gets lots of moisture. I have this variety planted next to our creek and it is extremely happy. I have another variety planted in a relatively dry but low area, so it collects the rain run off in the yard and stays damp longer there. It live and grows just a little very year, but does not thrive like the one on the creek's edge. This plant does not seem to mind that it is in Z5 (with lots of snow cover). Great plant 12 months of the year. As a matter of fact I just saw yesterday an all green mini acorus in a local nursery that only gets 2-4" tall. I will have to pick up.


On Apr 28, 2005, henryr10 from Cincinnati, OH (Zone 6b) wrote:

This is a very nice addition to add winter interest to the pond.
Not to say that it's not a great plant the rest of the year but green in winter...................
It spreads rapidly but is not really invasive in our climate.
I find it does very well in containers and just regular garden soil.
Come Spring just un-pot slice into quarters repot the divisions.
By mid Summer it's again filling the pots.
I've given away tons of this plant.


On Apr 21, 2004, pottingsisters wrote:

Wonderful plant - we use it extensively for color and texture in our container garden plantings. We find it does not require as much moisture as suggested - altho we flood our pots when watering. However, we have not used in boggy areas or wetlands, along streams as suggested. This is a plant we would not be without.


On Mar 19, 2004, wnstarr from Puyallup, WA (Zone 5a) wrote:

Edgewood, Washington
Nice plant for the edge of a pond. It is short and compact, adds a ray of sunshine to all the green around the ponds.