by Geri Williams

Heuchera – don’t cut back

I recently watched a video on 10 plants not to prune in the fall and it started me doing more research on which shrubs and perennial plants should or should not be pruned in the fall as part of our yard clean up.

Some plants should not be pruned in the fall because they bloom on old wood and cutting them back now cuts off next years blooms. Included in this group are rhododendrons, azaleas, viburnums, forsythia, magnolia, and hydrangea. All of these plants should be pruned soon after they flower. If one of these shrubs has gotten too big or out of shape you can cut it back this fall but you will be sacrificing your flowers next spring.

Some other plants should not be pruned or cut back now because they frequently die back with the cold winter weather. You increase the chances and amount of die back by exposing their branches with fresh cuts late in the season. Better to wait until next spring. Among this group are roses (but clean up and dispose of any diseased foliage), lavender, Russian sage, clematis, and butterfly bush. I have lost a couple of butterfly bushes that I pruned back in the fall because they had gotten long and sprawling. I have since read it is best to cut a butterfly bush back in early spring to 12 inches to get a bushier plant.

Phlox still blooming in October garden

Other plants need their leaves and plant mass to protect them from the winter elements particularly freeze and thawing which can cause them to heave out of the ground. Leave them be all winter and cleanup the dead leaves and stems in the spring when the new growth begins. Some of these plants are tall sedums(like Autumn Joy), heuchera or coral bells, hellebores, ferns, and ornamental grasses. If you bought some garden mums this fall and planted them in your garden, do not cut off the dead blooms, leaves and branches, they protect the root mass all winter. In the spring cut off the dead, being careful not to cut the new growth. Pinch back the shoots when they are 6-8 inches tall to create bushy round plants late summer.

To insure healthy plants next year you should cut back peony foliage leaving about 2 inches of stem once it has died. This is important to get rid of disease such as powdery mildew and botrytis. Similarly if columbine leaves show signs of leaf miner, little white squiggles in the leaves, or powdery mildew, cut it down to the base and dispose of the leaf material in household waste. Do not compost it. For tall garden phlox you should cut out any mildew stems during the growing season and cut all stems down to the ground in the fall. Dispose of all the stems in the trash if you had mildew during the season. If your bee balm (monarda) had mildew cut it down and dispose of in the trash. But if it is healthy you can leave it standing all winter along with your coneflowers and black eyed Susans. Their seed heads feed the birds and hollow stems provide nesting places for many native bees and other pollinators.

Azalea with next year’s buds

If you plan to spread lime and or fertilizer on your lawn this fall, which is the most effective time to spread these, please do not spread them within 100 feet of the ponds or streams. They can run off and pollute our water. I spread 1/2 to 1 inch of compost on my lawn within 100 feet of the pond instead.

Finally I’ll encourage you again this year to leave as many of your fallen leaves in your yard as you can. I pile many leaves onto my garden beds for winter protection and to allow the caterpillars, native bees and other insects that live in the leaves to survive. We pile the excess oak leaves in an inconspicuous area to compost naturally giving us soil enrichments in a couple of years.

Doing less pruning and garden clean up saves you time to enjoy the fall and helps keep many plants stronger over the winter, feeds our birds, and provides us with a more interesting view of the garden this winter.

“We come from the earth, we return to the earth, and in between we garden” – Alfred Austin