Acorus americanus

Acorus americanus Sweet Flag


 Confirmed Request

Acorus americanus (Sweet Flag) matures to 2' in height. It prefers wet to wet-mesic soil conditions, growing best in full sun. It can tolerate partial water emersion so would make a good choice for shoreline restorations or pond edges.  

Muskrats often eat the roots of Acorus americanus, seemingly attracted by the cinnamon-like scent. Emerging directly from the roots, the stemless leaves of Sweet Flag are sword-shaped and a colony of them may look like Cattails or Iris leaves from a distance. Green-yellow flowers protrude in cylindrical arcs in mid-summer.

Other common names include Calamus Root, Flag Root, Muskrat Root, Sweet Calomel, and Sweet Sedge. The "Sweet" in the name comes from the sweet aroma the leaves give when broken. Traditionally all Acorus plants in North America were called Acorus calamus, but that name should be restricted to the Eurasian species, which has been introduced to North America.  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.

Dormant bare root plants ship each year during optimal transplanting season: Fall (October) or Spring (April/May).
Acorus americanus - Sweet Flag

Map Key

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.

2 Questions asked on Acorus americanus

Q Chaska • November 24 Is this plant triploid or diploid? Thank you!
A Prairie Moon • November 27 Hi Chaska - great question! Unlike Acorus calamus, Acorus americanus is diploid.
Q Chris DeRhodes • January 23 Germination is listed as C(60) while the USDA’s page lists it as needing no stratification at all. Thoughts on this? Thanks.
A Prairie Moon • January 23 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.

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


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


Trays of 38 plants and 3-packs leave our Midwest greenhouse based on species readiness (well-rooted for transit) and based on order date; Spring shipping is typically early-May through June, and Fall shipping is late-August through September. Plant cells are approximately 2” wide x 5” deep in the trays, and 2.5" wide x 3.5" deep in the 3-packs; ideal for deep-rooted natives. Full-color tags and planting instructions/care 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 wholesale 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: $7.50
over $50.00: 15% 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 a day or two upon receipt.

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 38 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 Number