Best grown in sandy, loamy, well-drained soils in full sun. Good drainage is essential. A taprooted plant which tolerates heat, humidity and some drought. Remove spent flower spikes to prolong bloom period. Thin flower stems tend to become leggy and flop, particularly when grown in rich soils, and plants can benefit from close planting or support from adjacent perennials. Plants (particularly those which typically grow tall) may be cut back in late spring by 1/2 to control size. May self-seed if spent flower stems are left in place in the fall.