Sweet Flag has been incorrectly offered for sale as an aquarium plant, but it does not tolerate permanent submersion.
It is a grass-like perennial herb, forming thick clumps of linear, usually 15-20 cm (6-8 in) long. They are usually dark green but those of the cultivar ‘Variegatus’ are striped green and yellow. The small spadices are composed of minute .
It does best in a light, but tolerates partial shade. It should not be exposed to direct sun. Because it is a typical marsh plant, it must be provided with continually wet conditions. Rotted turves and peat are an ideal growing medium, which must never become dry. Feeding is not necessary. Propagate by dividing the clumps. This can be done when .