The Calamus is generally described as a perennial forb/herb. This is native to the U.S. (United States) has its most active growth period in the spring and summer . The greatest bloom is usually observed in the late spring, with fruit and seed production starting in the summer and continuing until summer. Leaves are not retained year to year. The Calamus has a moderate life span relative to most other plant species and a moderate growth rate. At maturity, the typical Calamus will reach up to 5 feet high, with a maximum height at 20 years of 0 inches.

The Calamus is easily found in nurseries, garden stores and other plant dealers and distributors. It can be propagated by bare root, container, sprigs. It has a none ability to spread through seed production and the seedlings have low vigor. Note that cold stratification is not required for seed germination and the plant cannot survive exposure to temperatures below -38°F. has none tolerance to drought and restricted water conditions.

Uses of : Landscaping, Medicinal, Culinary, etc.

Cultural Primarily, sweet flag is or was known by the American Indian tribes and early settlers for its medicinal value. Although the preparation of this species and the ailments it treats vary somewhat among the tribes, rhizomes are the most commonly used part.

Wildlife Sweet flag provides habitat for waterfowl. Muskrats eat the rhizomes and wood ducks consume the seed.

General Characteristics

Sweet flag is a perennial, rhizomatous, iris-like herb. The erect, sharp-pointed, sword-shaped leaves fan-out from a pinkish base and grow to 5 feet in length. The midvein is usually off-center. Cut or bruised leaves produce a sweet, tangerine-like scent. The flower stem, or scape, arises from the base of the outer leaves. Although resembling a leaf, the scape is triangular in cross section. A long, erect bract, or spathe, extends beyond the scape. A single, cylindrical 2 to 4-inch spike, or spadex, angles upward at this union. The slightly curved spadix is crowded with small yellowish-green to brown flowers that appear from May to July. Sweet flag has thick, creeping rhizomes with brownish exteriors and white, fleshy interiors.

Required Growing Conditions

Sweet flag is irregularly circumboreal. In North America it is found from Nova Scotia and Quebec to Minnesota, Alberta and Eastern Washington, south to Florida, Texas and Colorado on wet soils and shallow water in ditches, marshes, river edges and ponds. It prefers full sun and a pH range from 5 to 7.

Cultivation and Care

Sweet flag can be propagated vegetatively by plant or rhizome division, and by seed. Vegetative propagation is best completed in the fall or spring using firm, healthy rhizomes cut into 2- to 4-inch sections. Plant sections in rich soil 4 - 6 inches deep and 1 foot apart. Separating individual sprigs from clumped plants is an alternative to using rhizomes. These should also be transplanted at 1-foot spacings.Seed should be planted during the fall or winter in a greenhouse. Fill a 2-inch deep tray with an organic soil mix, scatter seed sparsely on the surface and press firmly into the soil. Do not bury further than 1/8 inch deep. Keep soil moist to saturated. Seed does not require stratification and germinates in less than 2 weeks. When plants reach 3 to 4 inches transplant into individual 4-inch pots. Pots can be placed in shallow water or irrigated frequently to maintain very moist to saturated conditions. Transplant outdoors 1 foot apart in the spring. With adequate moisture seed can also be planted outdoors spring through early summer, or in a cold frame late summer through fall.

General Upkeep and Control

Keep soil very moist to saturated; sweet flag does not tolerate droughty conditions. It grows well under seasonal, shallow inundation, however, avoid flooding of newly established plants or seeded areas.

Starter fertilizers may be used indoors to improve early growth but are unnecessary once transplanted outdoors into a rich soil.

The spadix will turn brown as the seed ripens in late summer or early fall. Seed can be planted immediately or stored in low humidity refrigeration.

Rhizomes should be harvested for medicinal use in early spring before new growth, or late autumn. Collect when large and firm, generally after 2 – 3 years of growth, before becoming hollow.

Plant Basics
Growth Rate Moderate
General Type Forb/herb
Growth Period Spring, Summer
Growth Duration Perennial
Lifespan Moderate
Plant Nativity Native to U.S.
Commercial Availability Routinely Available
Physical Characteristics
Bloom Period Late Spring
Displays Fall Colors No
Shape/Growth Form Rhizomatous
Drought Tolerance None
Shade Tolerance Intolerant
Height When Mature 5
Vegetative Spread Moderate
Flower Color Yellow
Flower Conspicuousness No
Fruit/Seed Abundance Low
Fruit/Seed Seasonality Summer Summer
Seed Spread Rate None
Gardening Characteristics
Propagations (Ways to Grow) Bare Root, Container, Sprigs
Moisture Requirements High
Cold Stratification Required No
Minimum Temperature -38
Soil Depth for Roots 12
Toxic to Nearby Plants No
Toxic to Livestock No
After-Harvest Regrowth Rate Moderate
After-Harvest Resprout Ability No
Responds to Coppicing No
Growth Requirements
pH Range 5.2–7.2 pH
Precipitation Range 32–32 inches/yr
Planting Density 2700–4850 indiv./acre
Soil Textures Coarse, Medium
Soil Depth for Roots 12
Minimum Frost-Free Days 90 day(s)
Salinity Tolerance Low
CaCO3 Tolerance Medium
Sustainability & Use
Leaf Retention No
Palatability Low
Fire Resistant No
Causes Livestock Bloating None

Source: USDA, NRCS, PLANTS Database,
National Plant Data Center, Baton Rouge, LA 70874-4490 USA