Deciding whether to cut back perennials or let them be
By Tracey Payton Miller
OSU Horticulture Educator
Several homeowners are wrestling with the same question: In the winter, should I cut back my perennials or should I let them be? Truth be told, there is not a right or wrong answer to the question. The best approach is to analyze research-based information that supports both techniques, and then decide which one will prove successful for you and your garden.
As the temperatures turn cold, many plants will begin to turn brown and lose some of their appeal. So it is the gardener's natural tendency to clean out, cut away, and remove any dead foliage in the garden. However, many perennials could benefit from keeping the dormant foliage for the winter. The canopy of spent leaves will protect the plant's crown by providing a blanket of insulation against harsh winter elements. The crown is the base of a plant and the position from which permanent roots grow. The leaf remains will also catch and distribute water to the root system.
So now, the once beautiful garden has a bunch of dead brown leaves lying around. Some may say the garden looks ugly, but one might prefer the phrase "showing its natural beauty." Many perennials can provide strong winter interest in a garden. Tall grasses can add structure and height in a blanket of snow. Seed heads from flowers like, Rudbeckia or Sedum, will have sharp color contrast against the white background. These seed heads can also attract hungry wildlife into the garden.
With all of these great reasons to leave the foliage on, why would anyone want to remove it? There are a couple reasons to support the other side of the fence. If a plant has been battling insects and diseases all season, removing the spent leaves is a good way to break the cycle. Insects and disease pathogens could over-winter in the same mass of leaves that provide the much needed protection for the plant crown. Disposing of leaves that have had problems will help fight off those nuisances. The blanket of leaves can also create a place for rodents to take up residence. So removing them would eliminate some prime real estate for mice communities.
Those are the facts. It is now in your hands as to what will work the best for your specific needs.