Cut back in fall PERENNIALS

By Marilyn McKinley

OSU Ext. master gardener volunteer

Several perennials, such as coneflower, provide food for the birds and offer visual interest when winter takes over. Perennial grasses are especially nice to see covered with snow.

On the other hand, some perennials do not handle rough weather, their foliage is ugly post frost, they provide little seed material for birds, they have recurrent problems with pests and diseases. Cut these down in the fall.

If you spot any plant that appears to be diseased, throw it out – do not compost. True, many gardens do well with no fall attention; there are exceptions to every rule. Cutting some will help tidy up the garden. Leaving others will help our pollinators and wildlife with winter food and housing.

What to cut:

Bearded Iris. It starts to flop come summer. By fall, it becomes a cover for iris borers and fungal diseases. Cut it back and toss out.

Blanket Flower. It is hardy, but since it is a favorite food for swallowtail caterpillars, often the stems are basically stripped.

Catmint (Nepeta). Likes to be pruned throughout the season. The foliage will be damaged by winter, so cut now.

Crocosmia. The flowers fall off, the foliage dies back, no reason to let it stand.

Hardy begonia. Frost blackens and collapses the foliage. If left it can cause crown rot.

Japanese anemone. Beetles love these plants and may strip it. When frosted, the foliage becomes black.

Penstemon. Does not like wet feet. If older, tall growth tends to flop and hold moisture. Cut to the ground.

Peony. Needs a cold period to set buds. They are very prone to powdery mildew, so just cut back and throw out. If left, healthy foliage turns golden then gets mushy from the frost.

Perennial sunflower. By frost time it is not as pretty, flowers have faded, cut the plants down.

Phlox. Also, prone to powdery mildew, cut it down, destroy foliage.

Perennial salvia. Likes to be pruned through the season, but in early fall as blooms fade, cut it back.

Daylilies. Mine look ragged now, I always cut them back, leaving about 3 inches.

Bee balm. True, it can be bird food, but it often gets powdery mildew. Newer varieties are more resistant. I always cut it down, but you could leave the seed heads for bird food.

Hardy geraniums. I think they look better and produce more blooms next year if they are cut back in fall.

Speedwell. Shear it to the ground; foliage will turn black and ugly.

Baptisia (false indigo). It will split down the middle if not cutback,. It’s another one that has black foliage after frost.

Yarrow. Doesn’t like to sit in cold wet soil. Cut back in early fall to allow new basal growth before frost.

Winter will come, winter will go. Getting started early will give you a head start on spring garden chores. For tips on pruning perennials now and throughout the year, go to:

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