No one can really pinpoint when frost and snow will come. Many gardens survive just fine with no attention at all in the fall. Consider this listing and the complementary Plants to Leave Standing Until Spring, as guidelines. You will learn what works and what doesn’t, for your own garden.
- Painted Daisy (Tanacetum coccineum) Painted Daisies can easily rot in wet soil. Prune in the fall to prevent the foliage from flopping over onto itself and acting as a mulch. (USDA Zones 3 - 7)
- Penstemon (Penstemon barbatus) Penstemon don’t like wet feet and should be planted a little higher in the ground than most plants. The foliage usually declines toward the end of summer and can be trimmed back, inducing new basal growth that is sufficient to mulch the plants through winter. Allowing the older, tall growth to flop would hold too much moisture around the crown. (USDA Zones 5 - 9)
- Peony (Paeonia) Peonies need a period of cold to set buds for the following season. That coupled with the fact that their foliage is extremely prone to mildew is reason enough to remove the foliage in the fall. Infected foliage can be removed and disposed of in late summer. Healthy foliage will turn golden in fall and can be removed once it has turned to mush, after the first frost. (USDA Zones 3 - 8)
- Perennial Sunflower (Helianthus) By this time Helianthus foliage isn’t a standout to begin with and by the time the flowers have faded, it’s also time to cut the plants down. (USDA Zones 4 - 9)
- Phlox (Phlox paniculata) Phlox is prone toward powdery mildew. Even the resistant varieties can become infected in bad weather. If so, prune and destroy all foliage and stems in the fall. (USDA Zones 4 - 8)
- Plume Poppy (Macleaya cordata) Try and kill a Plume Poppy, I dare you. Cut these back before they go to seed or you will have Plume Poppies EVERYWHERE. (USDA Zones 3 - 8)
- Salvia (Salvia nemorosa) Perennial Salvia benefits from several prunings during the growing season. In fall when blooming slows, cut the whole plant back to the new basal growth. (USDA Zones 3 - 8)
- Siberian Bugloss (Brunnera macrophylla) Although it’s not necessary, since Brunnera is an early riser in the spring and its foliage will turn black and unattractive with the first frost, fall clean-up is preferable. (USDA Zones 3 - 8)
- Sneezeweed (Helenium autumnale) Helenium usually doesn’t finish blooming until mid-fall, but by that time it is often covered with mildew. The foliage can be cut back and removed before winter. (USDA Zones 3 - 8)
- Solomon’s Seal (Polygonatum odoratum) Although listed here, Solomon’s Seal pretty much disappears on its own, after a frost or two. Certainly the leaves will drop. If the stems remain, they can be pruned back to the ground. (USDA Zones 3 - 9)
- Veronica / Spike Speedwell (Veronica spicata) As flowering ceases, the plants can be sheared to the ground. They will only turn black and ugly if left until spring. (USDA 3 - 8)
- Wild or False Indigo (Baptisia australis) Baptisia is one of those plants that splits in the middle if not sheared back after pruning, however many gardeners like the seed pods and simply stake the plants. Come frost, the foliage turns black and even staking isn’t going to help its appearance. Cut back for aesthetics. (USDA Zones 3 - 9)
- Yarrow (Achillea) Achillea don’t like to sit in cold, wet soil. By fall, most of their blooms are spent and the foliage is flopping and possibly diseased. Cut back in early fall and new basil growth with fill in before frost. (USDA Zones 4 - 8) Till next time this is Becky Litterer from Becky's Greenhouse, Dougherty Iowa