Should you put away the pruners? Yes and no
To cut back or not to cut back?
That is another question I am sure William Shakespeare asked fellow gardeners in London in the late 16th century, and gardeners are still asking the question today.
Some gardeners prefer a blank slate before a blanket of snow covers their gardens - you know the type. These gardeners like things tidy. Others are nonchalant about garden cleanup, preferring to leave it all standing - spent flowers and frosted foliage - until spring.
While most perennials don't care if they are cut back in fall or left in the garden until spring, there are some general guidelines on when to cut and when to wait.
Wait to cut back perennials that add interest to the winter landscape.
Many ornamental grasses stand up to all but the wettest, heaviest snows, providing structure in the winter garden. The tall stiff stems of Joe-Pye weed (Eupatorium maculatum Gateway), the blackened seed heads of false blue indigo (Baptisia australis), the flat-topped flower clusters of sedum, and the spent orbs of globe thistle (Echinops ritro) and alliums are all delightful dusted with snow.
Wait to cut back perennials that feed the birds.
Perennials with nourishing seeds for birds include black-eyed Susan (Rudbeckia), perennial sunflowers (Heliopsis), and coneflowers (Echinacea). Birds also belly up to the buffet if the garden includes goldenrod (Solidago) and asters.
Wait to cut back perennials that provide shelter for beneficial insects.
Native plants, like cup plant (Silphium perfoliatum), spiderwort (Tradescantia ohiensis) and bee balm (Monarda didyma) offer shelter to beneficial insects that overwinter in or near them as pupae, caterpillars or eggs.
Wait to cut back perennials that need extra protection to make it through the winter.
The foliage left standing over some marginally hardy perennials or those prone to frost heaving gives them a little extra protection. The stems catch windblown leaves and snow, providing an extra layer of insulation. Examples of these include anise hyssop (Agastache), butterfly weed (Asclepias), lavender, Russian sage (Perovskia), coral bells (Heuchera), foam flowers (Tiarella) and foamy bells (Heucherella).
Wait to cut back low-growing, semi-evergreen or evergreen perennials.
Barrenwort (Epimedium) and moss phlox (Phlox subulara) are evergreen ground covers that remain green through all but the harshest of winters. Wait to prune out winter-damaged foliage in spring. Sedges (Carex) form pleasing mounds of evergreen foliage. Clean these in spring by using hands donned with dishwashing gloves to comb through foliage, removing brown leaves. The leathery, lush green foliage of hellebores contribute rich color to the winter landscape, but should be removed before new growth begins in spring.
Cut back perennials with disease or insect problems to reduce the chance they'll be back next year.
Remove all the plant debris from garden phlox, bee balm and peonies to reduce the risk of powdery mildew overwintering in the garden. Cut back the foliage of black-eyed Susan if they were infected with leaf spot; remove the old leaves of bearded irises to eliminate iris borers that spend the winter as eggs in plant debris. If hostas were assaulted by slugs, leaving behind holey leaves and slime trails, clean out all the foliage to eliminate their winter vacation homes and to expose their eggs to hungry frogs and toads.
Cut back perennials that set seed if self-seeding is unwanted.
Some plants spread their progeny with abandon across the landscape. As pretty as Joe-pye weed is in the winter garden, it casts seeds that fill next year's garden with seedlings. The most seedlings occur in gardens without mulch. Cup plant and false blue indigo are other examples of plants that generously share their seeds. Even if you don't cut these perennials down to the ground, at least remove all their spent flowers before they set seed.
• Diana Stoll is a horticulturist, garden writer and the garden center manager at The Planter's Palette in Winfield. She blogs at gardenwithdiana.com.