By Cliff – originally posted to Flickr as Japanese Sweet Flag (Acorus gramineus), CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=6590648

Acorus gramineous (Acoraceae family), which is also known as sweet grass, Japanese sweet flag or rush, is a low growing, herbaceous, evergreen and perennial ground cover. Because of its grass-like, fragrant, narrow and long leaves, it is used in a variety of ornamental grass themed landscapes. However, it is not an actual grass. Acorus gramineus is native to Asia, in particular the wetlands of Japan, China, Thailand, Korea and the Philippines. In the US, it is hardy to USDA Planting Zones 5 – 9 and can reach a height and spread up to 1 foot. In early summer, the plant produces flowering spikes with green and yellowish tiny blooms which eventually generate tiny, inedible, red berries.

Acorus gramineous prefers full Sun to part shade. It performs extremely well in moist or boggy soil and can easily be incorporated in rain, water (grown in containers) and bog gardens. Because they naturalize readily, they can tolerate some erosion (plants can help control it on water banks) and even full shade in most locations. The soil however, must remain moist to ensure healthy plants. In warm climates, the plants will benefit from some afternoon shade during hot and dry conditions. They need to be overwintered indoors however, in colder regions (Zones 1-5). Fortunately, Acorus gramineous does not suffer from serious pest or plant diseases but moist soil is essential to prevent scorching of the leaves.

Utilizing Acorus gramineous in masses, including the dwarf, variegated variety called ‘Ogon’ which produces yellow and greenish leaves, can ensure ongoing interest and beauty to any ornamental landscape.