Acorus americanus

Sweet Flag

$3.00 - $150.00

1/8 oz.
1/4 oz.
1/2 oz.
1 oz.
1 lb.


Sweet Flag forms stands of sword-shaped, stemless leaves that fan out directly from the roots. A colony of them may look like cattails or iris leaves from a distance. Green-yellow flowers protrude and arc from stiff spathes in mid-summer, giving way to fleshy berries which turn a rich brown as they dry in the summer heat. The "sweet" in the name comes from the aroma the leaves give off when broken.  Muskrats often eat the roots of Acorus americanus, seemingly attracted by the spicy, cinnamon-like scent. 
Maturing to 2 feet in height, this plant prefers to keep its feet wet or damp and grows best in full sun. The leaves will start to scorch if the soil dries out.  Sweet Flag spreads by rhizomes and, in the preferred conditions, can form large colonies.  That dense root system stabilizes the soil.  These qualities, plus the plant's ability to tolerate immersion for periods of time, make it an excellent choice for pond edges and shoreline restorations. 

It is thought that Native Americans played a role in the distrubution of this plant since they likely traveled with and traded it; the root was prized as a medicinal remedy for common things like nausea, colds, and heartburn.

Other common names include Calamus Root, Flag Root, Muskrat Root, Sweet Calomel, and Sweet Sedge.

Live Plant Shipping Table

Spring Fall Age/Size
Dormant Bare Roots
April/May October 1 year

Acorus americanus - Sweet Flag

Map Key

Present in state
Present but introduced in county
Present and native in county; not rare
Not present in state
Present and native in county; rare
Species extirpated (historic)
State or county listed as noxious
Present in state; exotic

This map shows the native and introduced (adventive) range of this species. Given appropriate habitat and climate, native plants can be grown outside their range.

3 Questions asked on Acorus americanus

Is this plant triploid or diploid? Thank you!
Hi Chaska - great question! Unlike Acorus calamus, Acorus americanus is diploid.
Germination is listed as C(60) while the USDA’s page lists it as needing no stratification at all. Thoughts on this? Thanks.
Thanks for writing, Chris. Sweet Flag is not a species that we have started from seed in our greenhouse. Most native wildflowers have seed that requires over-wintering outdoors to break germination inhibitors, so C(60) seems like a reasonable code for this species. Because Acorus americanus is a wetland plant, even capable of emerging from standing water, it could germinate in favorable swampy conditions without its seed over-wintering. The seed’s natural cycle, though, would be to ripen on the plant, then to fall to the soil, over-winter and sprout the following spring.

If you are interested in experimenting, you might try sprouting some seeds after cold, moist stratification, and some without pre-treatment. We’d be interested in your results.
Are the leaves of Sweet Flag stiff enough to stand all season or do they flop similar to Siberian iris?
Hi Tena. Sweet Flag foliage is typically sturdy enough to stay upright throughout the growing season. Various weather and site conditions can make the leaves flop, though.


Growing your own plants from seed is the most economical way to add natives to your home. Before you get started, one of the most important things to know about the seeds of wild plants is that many have built-in dormancy mechanisms that prevent the seed from germinating. In nature, this prevents a population of plants from germinating all at once, before killing frosts, or in times of drought. To propagate native plants, a gardener must break this dormancy before seed will grow.

Each species is different, so be sure to check the GERMINATION CODE listed on the website, in the catalog, or on your seed packet. Then, follow the GERMINATION INSTRUCTIONS prior to planting. Some species don't need any pre-treatment to germinate, but some species have dormancy mechanisms that must be broken before the seed will germinate. Some dormancy can be broken in a few minutes, but some species take months or even years.

Seed dormancy can be broken artificially by prolonged refrigeration of damp seed in the process of cold/moist STRATIFICATION. A less complicated approach is to let nature handle the stratifying through a dormant seeding, sowing seeds on the surface of a weed-free site in late fall or winter. Tucked safely beneath the snow, seeds will be conditioned by weathering to make germination possible in subsequent growing seasons.

To learn more, read our BLOG: How to Germinate Native Seeds

Dormant Bare Root Plants

We dig plants when they are dormant from our outdoor beds and ship them April-May and October. Some species go dormant in the summer and we can ship them July/August. We are among the few still employing this production method, which is labor intensive but plant-friendly. They arrive to you dormant, with little to no top-growth (bare-root), packed in peat moss. They should be planted as soon as possible. Unlike greenhouse-grown plants, bare-root plants can be planted during cold weather or anytime the soil is not frozen. A root photo is included with each species to illustrate the optimal depth and orientation. Planting instructions/care are also included with each order.

Download: Installing Your Bare-Root Plants

Potted Plants

3-packs and trays of 32, 38, or 50 plants leave our Midwest greenhouses based on species readiness (being well-rooted for transit) and order date; Spring shipping is typically early May through June, and Fall shipping is mid-August through September. Potted 3-packs and trays of 38 plugs are started from seed in the winter so are typically 3-4 months old when they ship. Trays of 32/50 plugs are usually overwintered so are 1 year old. Plant tray cells are approximately 2” wide x 5” deep in the trays of 38 and 50, and 2.5" wide x 3.5" deep in the 3-packs and trays of 32; ideal for deep-rooted natives. Full-color tags and planting & care instructions are included with each order.

Download: Planting and Care of Potted Plants

*PLEASE NOTE: we are a mail order nursery and have no retail facilities, but you may pick up your order if prior arrangements are made. Pick up orders are subject to **MN Sales Tax.

Shipping & Handling Charges

SEED $100.00 and under: $5.00
Retail SEED orders over $100.00 ship free!

Custom seed mixes or discounted seed sales over $100, add 5% of the total seed cost
(for orders over $1,000 a package signature may be required)

BARE ROOT and POTTED PLANTS $50.00 and under: $9.00
over $50.00: 18% of the total plant cost. (For orders over $1,000 a package signature may be required.)

TOOLS and BOOKS have the shipping fee included in the cost of the product (within the contiguous US).

**We are required to collect state sales tax in certain states. Your state's eligibility and % will be calculated at checkout. MN State Sales Tax of 7.375% is applied for orders picked up at our MN location. Shipping & handling charges are also subject to the sales tax.

Shipping Season

SEED, TOOLS and BOOKS are sent year-round. Most orders ship within 1-3 business days.

BARE ROOT PLANTS are shipped during optimal transplanting time: Spring (April-May) and Fall (Oct). Some ephemeral species are also available for summer shipping. Since our plants are field-grown, Nature sets the schedule each year as to when our season will begin and end. We fill all orders, on a first-come, first-serve basis, to the best of our ability depending on weather conditions beyond our control.

POTTED PLANTS (Trays of 32/38/50 plugs and 3-packs) typically begin shipping early May and go into June; shipping time is heavily dependent on all the species in your order being well-rooted. If winter-spring greenhouse growing conditions are favorable and all species are well-rooted at once, then we ship by order date (first come, first serve). We are a Midwest greenhouse, and due to the challenges of getting all the species in the Mix & Match and Pre-Designed Garden Kits transit-ready at the same time, we typically can't ship before early May. Earlier shipment requests will be considered on a case-by-case basis.

*We are unable to ship PLANTS (bare root or potted) outside the contiguous US or to CALIFORNIA due to regulations.


We ship using USPS, UPS and Spee Dee. UPS and Spee Dee are often used for expediting plant orders; they will not deliver to Post Office Box numbers, so please also include your street address if ordering plants. We send tracking numbers to your email address so please include it when you order.



Germination Code
Life Cycle
Sun Exposure
Soil Moisture
Wet, Medium-Wet
2 feet
Bloom Time
May, June, July
Bloom Color
USDA Zones
Plant Spacing
Catalog Code