Sweet flag is an unusual plant indigenous to India, although now it grows in wetland conditions all over the world. Hardy from Zones 4 to 9, sweet flag will grow in a variety of environments, as long as they are wet enough. Sweet flag grows best in ponds or bogs and is used as an ornamental grass in most cases, although it will grow in damp ground. Sweet flag does have long, stalk-like flowers that only bloom when grown in water.
Choose a spot to plant your sweet flag. It grows best as an aquatic plant in or beside a pond, although it will grow in constantly damp ground as well. Sweet flag grows best in full sun to partial shade.
Dig a hole for your sweet flag about 6 inches deep and 4 inches in diameter. Place the plant in the hole and cover with soil or mud. Sweet flag can even grow when planted slightly underwater.
Water your sweet flag every day for 10 minutes each watering, if it is not next to a water source already. The ground around the sweet flag must be constantly moist.
Divide the rhizomes of 2-year-old sweet flag to grow more plants, if desired. Repeat Steps 2 and 3, with the rhizomes planted about 6 inches apart from each other.