Plants may be slow to appear in the spring, but be patient and you'll be rewarded with blooms that persist long after other perennials have completed their show. Plants generally do not require support. Deadhead stalks in the fall. Monitor for four-lined plant bug. Aphids may be a problem on plants grown in infertile soil.
Powdery mildew can cause a white coating on leaves.
Sprays of sulfur or benomyl control the problem. Rust causes numerous brownish pustules on undersides of leaves. Sprays of sulfur should keep this disease under control. Some have reported an unexplained problem, perhaps a virus, in early spring that causes pale-yellow foliage growth. False sunflower, rough heliopsis , hardy zinnia, oxeye.