How should I prepare my perennial beds for winter?
Perennial plants can be cut back in fall after the foliage has been destroyed by a hard freeze. Compost the plant debris. Most established perennials (those in the ground 1 or more years) do not require winter protection. However, a few perennials, such as garden mums, can be damaged in winter and should be mulched in fall to prevent injury. Perennials planted in late summer/early fall should also be mulched. Good mulching materials are clean, weed-free straw, pine needles, and chopped cornstalks. A 6- to 8-inch-layer should be adequate for most perennials. Mid- to late November is usually a good time to mulch perennial beds in Iowa.