28. SHOULD I CUT BACK IN WINTER OR NOT?

Most herbaceous perennials die back to ground level during the cold season, but some others may not disappear. Their stems and foliage remain standing, dried and brown, in late fall and early winter. Some gardeners may see this as unsightly debris and wonder if they should cut back the spent foliage. If you don’t mind the look, and there is no disease present, you need not cut down these plants until late winter or early spring. In fact, it is now recommended to leave most perennials intact during winter instead of cutting them back to the ground. The stems and dried flowers add interest to the winter landscape, provide some insulation from the cold, and act as overwintering habitat for some birds, butterflies, and bee species.

Some perennials are sensitive to the cold, and these benefit from remaining intact overwinter. Do not cut back asters, Russian sage, red hot poker, lavender, chrysanthemums, and lady’s mantle. Perennials with evergreen or semi-evergreen foliage should not be cut back until spring. These include foamflower, coral bells, and evergreen hellebores.

Other perennials should be left standing simply for their winter display interest, such as joe-pye weed. These stately plants add a new dimension to the dormant landscape. More important, the dried seed heads of certain flowers feed overwintering birds. So do not cut back purple or white coneflower with its oil-rich seeds, which goldfinches love. Also leave black-eyed Susan, sedum plants, globe thistle, and cup plant (Silphium perfoliatum) to dry naturally in the garden.

While some perennials like daylilies, irises, and peonies should be cut back to prevent disease and insect attack, many others should be allowed to remain standing over the winter. Just remember to cut them back in late winter to early spring before new growth emerges.

The late summer-blooming Russian sage (Perovskia atriplicifolia) has somewhat woody stems. You can leave the plant standing for winter interest. In the spring, prune it back to about 8 inches high before new growth starts