As fall approaches, horticulturists with Iowa State University Extension and Outreach are lending some tips of caring for peonies. The flowers thrive in Iowa but can sometimes get a white, powdery material on the foliage that is a fungal disease. This mildew occurs on many plants, including roses and lilacs, but seldom causes serious harm to plants. Moving peonies to a sunny location helps reduce the mildew. Peonies can be successfully transplanted in mid-September to early October, when doing so be sure to keep the root system intact as much as possible. That is also the best time to divide peonies, and each division should have three to five buds and a good root system. Also, peony foliage should not be cut back until after a hard freeze in the fall because it manufactures food for the plant.