Acorus gramineus ‘Ogon’

Sweet flag cultivar (Acorus gramineus) is an iris-like perennial usually planted for its wavy drifts of golden yellow foliage. This dwarf ground cover, indigenous to China, Korea and Japan, grows 6-12 inches tall. Sweet flag is a member of the acorus family (Acoraceae) (USDA hardiness zones 6-9 and should be winter protected in zone 5).

Green variegated leaf cultivars with striped yellow or green blades are also available. The narrow leaf blades barely measure ¼ inches across. A bright patch of sweet flag spread slowly by creeping roots (rhizomes). Foliage gives off a citrusy scent when pinched or stepped upon. Sweet flag copes with only light foot traffic. In June or July tiny greenish yellow sedge-like flowers appear followed by tiny fleshy berries; flowers and fruits offer little in ornamental value.

Growing requirements for sweet flag are similar to that of most sedges (Carex spp.). Sweet flag grows in average garden soil and in full sun to partial shade (depending on location). It can tolerate heavy shade but its rich golden hue is lost. To succeed, sweet flag wants above average soil moisture; it thrives in shallow boggy conditions such as around a water garden. Scorched leaf tips arise when the soil becomes parched. In southern climes, plant sweet flag in afternoon shade or full day filtered sunlight. Foliage stays evergreen in warmer zones.

Sweet flag has no serious disease or insect problems. In early spring a single application of slow-release organic base fertilizer is adequate.

Sweet flags are utilized as textural and color accent plants around water gardens, streams, ponds, or in moist open woodland gardens. It is also planted in rock gardens or border fronts. Sweet flag can be used to edge decorative containers.

Leading cultivars:

‘Ogon’ – the most popular form with golden-colored foliage.

‘Minimus Aureus’ – 3-4 inch tall miniature  ground cover that forms a golden mat; plant some between stepping stones (emits light citrus fragrance).

‘Variegatus’ – grows 6-9 inches tall with white-and-green striped grassy foliage.