ACORUS: Japanese Sweet Flag
Acorus are grown primarily for their bright, cheery evergreen foliage that is clumping and grass-like in character. The plant's flower spikes are largely inconspicuous on Acorus gramineus, while they are larger on Acorus calamus. The leaves of Acorus gramineus are in flattened fans like those of irises, crowded along short rhizomes, while the leaves of Acorus calamus are taller. Both leaves and rhizomes of both species are sweet-scented and the stout, aromatic rhizomes of Acorus calamus contain compounds sometimes used in herbal medicines or perfume.
Acorus calamus is a perennial associated with wetlands throughout Eurasia and eastern North America. Acorus calamus has green iris like leaves to 5 feet long and a narrow elliptical green spadix (a fleshy spike bearing small flowers) to 4 inches long. This species spreads slowly by underground rhizomes and is evergreen throughout most of its range. Acorus calamus 'Variegatus' has cream and yellow variegated leaves.
Acorus gramineus is a great addition to mixed containers for sun or shade. It adds a wonderful pop of color and stays compact. In addition, because it is evergreen, it can be used in containers for all seasons and is especially fun in winter when options for grasses are more limited. Acorus gramineus also adds color and consistency to the front of mixed plantings or simple modern plantings where it looks especially good planted en masse. Also, Acorus gramineus can be a fantastic groundcover between pavers in a location where adequate moisture is assured. Acorus calamus is a showy and reliable water plant suitable for water gardens in the Pacific Northwest. Acorus calamus 'Argenteostriatus' is a variegated variety of the native that provides a bright spot of color and structure to the water garden.
Native to Japan, this species has green, soft curved leaves up to 18 inches long. The flower spikes are about 3 inches long and emerge in spring and summer. Clumps can be up to 2 feet wide and are slow to grow. Varieties include the following:
Acorus gramineus 'Golden Pheasant'
This variety has chartreuse to golden colored foliage and grows between 12 to 14 inches tall.
This variety has bright yellow foliage with a fine texture and grows to 4 inches tall.
Acorus gramineus 'Ogon'
This variety has gold and green variegation and grows from 10-12 inches tall.
This variety has white and green variegation and grows from 8-12 inches tall.
Acorus gramineus 'Yodo-No-Yuki'
This variety has olive-green foliage with a light yellow edge and grows up to 12 inches tall.
Acorus gramineus 'Hakuro-nishiki'
This variety has yellow-green foliage and is compact in nature.
Common Name: Japanese sweet flag, sweet flag, flagroot, sweet calamus
Origin: A sedge-like genus of two evergreen perennial species (Acorus gramineus and Acorus calamus) from temperate East Asia and southeastern United States.
Culture: Acorus species are tough and easily grown. Because Acorus are native to pond margins, they prefer fertile, acidic soil that is constantly moist. Acorus resent drying out and will produce brown tips and burnt foliage. They tolerate sun to part shade conditions.
Maintenance: Acorus do not require much maintenance, however, they will benefit from division every few years when the center of the clumps become sparse. At this point, divide the rhizomes and replant them. Otherwise, maintenance includes cutting out dead or bad-looking foliage and keeping the plant moist.
Pests and Diseases: Acorus are prone to slug damage.