Sweet Flag (Acorus americanus) | Prairie Restorations

Sweet Flag

Acorus americanus

Acorus americanus, or Sweet Flag, is a perennial wetland plant that grows between 2 to 6 feet tall. It features sword-like, aromatic leaves and produces small, greenish-yellow flowers on a spadix from late spring to early summer. Sweet Flag commonly inhabits marshes, lakes, stream banks, and wet meadows, preferring calcareous and peat soils. Traditionally, it has been utilized by Indigenous peoples for medicinal purposes and as a flavoring agent. In landscaping, Sweet Flag is employed in rain gardens and along pond edges for its ornamental foliage and ability to stabilize soil.

Characteristics

Product Form	Plant, Seed
Type	Forb
Sun	Full Sun, Partial Sun
Soil	Clay, Loam, Sand/Gravel, Peat, Calcareous
Moisture	Wet, Aquatic
Average Max Height (inches)	40
Suggested Plant Spacing (inches)	12
Bloom month(s)	June, July
Bloom Color or Type	Green
Dominance	Medium

Range Maps

Sowing Information

Sow seed onto a firm, weed-free seedbed. Hand-broadcast seed making two perpendicular passes for even coverage. If planting a mix, broadcast the grass component first and lightly rake/drag it into the top 1/8–1/4" of soil. Next, broadcast wildflower/forb seed and press it into the soil surface (with a roller/cultipacker or the back of a rake) to ensure good seed-to-soil contact. After seeding, apply a very light layer of clean, seed-free straw (or other weed-free, site-appropriate mulch) to reduce erosion and retain moisture without smothering seedlings. A good rainfall or thorough watering will help settle seed and mulch and improve germination.

Planting Information

Dig a hole in your planting site slightly larger than the plant’s root system. When placing the plant into the hole, ensure that the soil line remains consistent with its original level in the pot. Fill in around the roots with the excavated soil, gently firming it to eliminate air pockets. Water the plant thoroughly the same day to promote successful establishment.