Flowers are said to begin blooming June 24, St. John's Day. Full sun to light shade. Not choosy about soil conditions. Plants can become weedy where grasses are not thick and may be difficult to eradicate. St. John's Wort is on the noxious weed list for several states in the West.
Stems are straight or branched.
Full sun to partial shade. Blue flag will also grow in up to 6 in. of standing water. Propagate by division in early spring. The common name refers to the white tips on yellow ray petals encircling golden flower centers. Well-drained soil that is moist at least in early spring.