After many centuries of being grown for use in herbal medicine, sweet flag, Acorus gramineus, is still a popular evergreen perennial; but is now appreciated more for its low mounds of grassy foliage. ‘Ogon’, one of the most popular cultivars, has light yellow variegated foliage that contrasts well with deep green foliage, or brightens partially shaded spots in the garden. Individual clumps grow quickly to about eight inches tall and broad, and then spread slowly by producing more shoots. New plants are easily propagated by division. Sweet flag likes plenty of water, and does well in partially submerged pots in koi ponds, or poorly drained spots.