Which Perennials to Cut Back - and which to leave standing….
As Midwest gardens wind down for the season, it’s natural to want to tidy things up. Cutting back perennials can help reduce disease and keep beds looking neat, but some plants actually benefit from being left standing through winter. Some perennials provide great winter interest and beauty throughout the barest months. The key is knowing which is which.
Good Candidates for Fall Cutback
Perennials with soft, collapsing foliage or those prone to fungal disease should be trimmed once frost has blackened their leaves. These include allium, anemones, liatris, astilbe, ligularia, bee balm, peonies, phlox, hostas, daylilies, and irises, some of which can harbor disease or slugs if left over winter. Cutting them to a few inches above the ground keeps things tidy and helps prevent problems next spring. Similarly, coreopsis, salvia, and nepeta can be cut back once their foliage browns, encouraging compact new growth next year.
Perennials to Be Careful With
Some plants are best left standing for their winter beauty or ecological benefits. Echinacea, rudbeckia, senna, and asters hold seed heads that feed birds and add structure to snowy gardens. Switchgrass (Panicum), little bluestem (Schizachyrium), and virtually all other ornamental grasses should remain until late winter—their crowns are protected from freeze-thaw cycles by the standing foliage. Likewise, leave fern fronds, heuchera, and hellebores in place until spring to shield tender crowns. Some other perennials that hold their structure and look great during the winter season are baptisia, amsonia, and mountain mint.
Finally, avoid cutting back woody perennials such as Russian sage (Perovskia) and lavender, which resent hard pruning in fall and are best trimmed lightly in spring once new growth appears.
Perennials to Absolutely Not Touch
There are several shrubs and perennials that bloom on old wood, so should never be cut down or pruned hard in the fall. These include oakleaf hydrangea, macrophylla hydrangeas (blues and pinks), and Itoh or Tree Peonies. Do not prune any spring flowering shrubs this late in the season or you will sacrifice your blooms next spring.
Roses are often cut back in the fall, but it is better for the plant to save your rose pruning for the spring. Provide some winter protection to the crowns with leaves or compost, then trim in the spring once new growth starts emerging.
A well-timed fall cleanup isn’t about making everything spotless—it’s about balancing neatness with nature. By knowing which perennials and shrubs to cut and which to leave, you’ll set the stage for a healthier, more beautiful garden next year.
