Asia; widely introduced in Europe, North America and elsewhere
Water
freshwater
Maximum size
200 cm
Temperature
4–24°C
pH
6–8
Hardness
Tolerant (estimate)
Care level
intermediate
Lighting
Full sun to part shade (pond marginal)
Care
Sweet flag is a tall, iris-like wetland plant of the family Acoraceae. It grows at the edges of lakes, ponds and rivers and in marshes, spreading by a thick, aromatic rhizome to form colonies. It is native to Asia (and probably the Irtysh valley in Kazakhstan) and has been widely introduced, including to Europe, where it is a familiar pond-edge plant. It is a marginal pond plant, not an aquarium plant. It reaches about 2 m, holds its leaves out of the water and flowers only when standing in water. Plant it in a basket in shallow water at the edge of a pond, in sun or part shade. A variegated form is sold for ponds. The leaves smell sweet when crushed. The plant contains beta-asarone and may be toxic if eaten; it is banned as a food in the US. As a hardy temperate marginal it suits outdoor ponds and is quite unsuitable for a tropical tank. Water figures are our estimate, not from the sources. Sources: Wikipedia (en.wikipedia.org/wiki/Acoruscalamus); Wikipedia, List of freshwater aquarium plant species. Checked October 2026.
Breeding
Divide the rhizome in spring and replant the pieces in shallow water or wet soil.
Compatibility and tank mates
A pond marginal for shallow water at the edge of garden ponds; too large and not aquatic enough for aquariums. Pond fish such as goldfish and koi leave the tough leaves alone.
Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.
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