Time to Cut Back Perennials

Perennial Border before Spring Clean Up

As long as the soil is dry enough to walk on, it’s time to start cleaning up perennial borders. As anxious as we are to get back in the garden, however, never walk on moist soil in the garden. It will cause soil compaction that may take years of amending with compost to correct. If you aren’t sure about the soil moisture, put a board down to walk on. It will distribute your weight and at least minimize compaction.

With pruners in hand, let’s get started. Some perennials get cut back all the way to the ground. The dead or ugly leaves are all that’s removed from others, and some perennials are just tip pruned. How do you know what kind of pruning to do? Most perennials fall into the cut back all the way to the ground category, so let’s save that group for last.

Campanula before Spring Clean Up

Some perennials, like bellflowers (Campanula spp.), Coreopsis, Shasta daisies (Leucanthemum x superbum) and yarrow (Achillea millefolium), keep low rosettes of evergreen basal foliage during winter. These ground-hugging leaves protect the roots when the rest of the plant dies back in winter. Cut back the dead stems of these first and then check out the basal foliage. This, too, can be trimmed if it has been ravaged by winter but it is tedious and usually unnecessary. If ignored, new spring growth will freshen up their appearance before Mother’s Day.

Sedum, Basal Foliage

Sedums also have succulent basal foliage. Remove dead stems to open it to sunlight.

Phlox subulata before Spring Clean Up

Evergreen perennials, like pinks (Dianthus spp.) and moss phlox (Phlox subulata), typically need little pruning. If winter was especially hard on them, wait until they have bloomed and then cut them back by half.

Winters in the Chicago suburbs can be kind or cruel. In years with reliable snow cover, semi-evergreen perennials need little pruning. Years with especially cold temperatures or periods without snow cover wreak havoc on them and most of their foliage is cut back.

Heuchera before Spring Clean Up

Examples of these include Bergenia, Heuchera, Heucherella, Tiarella and some ferns.

Epimedium before Spring Clean Up

This winter was hard on Epimedium in my shade gardens. All of it will be cut back.

Woody perennials are best left standing until new growth begins. These are then tip pruned down to plump healthy buds. Although it may sound misleading, tip pruning doesn’t necessarily mean cutting just the tips off. Instead, it means cuts are made back to strong new spring growth. The type of winter will determine how far down the tips of stems cuts will be made.

Examples of perennials to tip prune include butterfly bushes (Buddleia), Caryopteris, lavender and Russian sage (Perovskia).

Carex 'Ice Dance'

At the end of most winters, some of the foliage of sedges has browned. Leaves could be cut out one by one but that might take until next spring. Instead, don one of those pairs of oh-so-stylish rubber gloves and use your fingers to comb through the foliage.

Hakonachloa macra

Allium before Spring Clean Up

Most of the rest of our perennials are cut back completely to the ground and all debris removed.

After all the brown plant material is removed, it won’t be long before fresh green foliage explodes from soil. Spring is officially just a week away!

Garden with me!

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