Knowing when to cut back perennials

I made a pact with myself this past spring: I will cut back most of my perennials in the fall rather than wait until the winter (like I did last year).

Time got away from me last fall, and I didn’t get into the garden to finish cleaning out my beds and preparing them for winter. I paid dearly for it last spring, when I had to not only plant my new stuff but had to cut back the old perennials and in some cases, annuals that I forgot to pull.

Therefore, this past spring, I said, “never again” and I am really trying to stick to this. I have been slowing and methodically pulling annuals and vegetables as they die and cutting perennials back once they no longer look good.

I like to wait to cut the perennials back, however, until after they have lost their ornamental value. For some, this might not be until next spring, and I’ll make an exception for them.

Ornamental grasses, for instance, look great most of the winter. The only downside might be if we get a heavy snow or ice storm that bends them in half. They tend to perk back up but don’t look as good.

I wait until early April to cut back the ornamental grasses. I also divide them at the same time if needed.

As far as the rest of the perennials, I evaluate their ornamental value each weekend and decide if it’s time or not. If they still look good, I let them go a little longer.

However, if they really don’t add to the overall quality of the garden, I cut them back to about 3-4 inches above the crown. If they are plants that grow from the ground and don’t have a true crown, I cut them back to the ground.

The latter group includes plants like Mondarda or bee balm, Physostegia or obedient plant, Asiatic lilies, and ferns.

There are some perennials that fall into the category of “I don’t know when to cut them back.” These include coral bells, hellebores and lamb’s ears.

These plants have a tendency to overwinter with the foliage looking pretty good. However, I have learned that there comes a period of time the next season when the old foliage starts to look pretty bad and has to be cut back.

I have determined to wait until spring on these, but to make sure that I cut them back early enough in the spring so that the new growth doesn’t get caught up in the old growth. If you have some of these plants, you know what I mean.

In terms of annuals (both flowers and vegetables), unless they absolutely have beautiful winter characteristics, I go ahead and clean them out of the garden in the fall. This way, I am prepared for spring planting.

I don’t mulch anything in my perennial beds. I simply don’t grow plants that aren’t extremely winter hardy. If you are going to protect your perennials or rose for the winter, wait until around Thanksgiving or after a few hard freezes before you apply the protective mulch.

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