Gardening: Perennial Pruning Primer – Keeping Perennials Looking Great

May 2016

By Pam Eagles, Wake County Extension Master Gardener

Off with their heads! This old saying was on to something back then, and it’s now part of our gardening endeavors. Spent, tired, old, bad form in the garden? Prune it!

The basic types of pruning are deadheading, cutting back, pinching, disbudding and thinning.  Depending on your garden needs, use these tips as your guide when tidying:

Deadheading is just as it sounds: removing the dead flowers from your plant. Removing the top or terminal flower when past its prime keeps your plant fresh looking. If you want the plant to go to seed, do not deadhead. You might notice seedlings popping up in unexpected places in your garden. If this does not appeal to you, deadhead.

Cutting back is the most drastic pruning method. You may cut back to within 2 inches of the ground. This method may be used before or after blooming. It is basically pruning to renew the plant’s appearance, and cutting back can help you control flowering time and plant height. Depending on your plant, it will be necessary to use hand pruners, hedge shears or, in some instances, your string trimmer. Plants should be cut back in cooler spring weather and kept well watered to reduce stress. Liriope is cut back in February before new growth is emerging.

Pinching removes only a small amount of the plant – the growing tips and first set of leaves. Your fingernails are the best tool for pinching. Pinch the stem of your plant just above a node.  Plant growth habit can be improved by pinching. Too tall and weak? Pinch it back. You can also control bloom time with pinching. Remove setting buds early in the season. They should reset and bloom later. Yarrow, artemesia and sedum respond well to pinching, and in these plants pinching helps control flopping or laying over.

Disbudding perennials refers to the removal of the plant’s terminal (top) or side buds. Removing the terminal bud allows the plants to focus energy on side buds, producing more flowers. Be aware the side flowers will be smaller but more plentiful. On the same note, removing the side buds will allow the terminal or top flower to be larger and have a longer stem for cutting. When you think disbudding, think dahlias, carnations and peonies.

Thinning is the removal of stems from a plant. Thinning your plant improves appearance, increases flower size and prevents disease. Cut the chosen stems to the ground in spring. A general rule is to thin one in three stems. Plants prone to mildew benefit immensely from the increased air circulation that thinning allows. Your bee balm, lamb’s ear and garden phlox will all be more beautiful with a little early-season thinning.

Perennial Pruning Primer

Nandina before pruning.

Perennial Pruning Primer

Nandina post-pruning

Perennial Pruning Primer

After 1 year’s growth & pruning

Azaleas and other early blooming shrubs have or are about to end their spring show in our gardens. If you have issues to address, it is now time to prune before they begin to set buds for next spring.

Nandina, or Heavenly Bamboo, may be looking leggy in the garden. Start by cutting your main stems back at least a third. Honestly, I have been known to cut more. If yours is an established plant, try staggering some of the stem cuts for a more layered, airy look.

Think size, form, damage and location when pruning. Use the proper pruning tool, and make clean, angled cuts. A little garden therapy will keep you happy and your garden lovely!

Pam Eagles is president and founding member of the Community Gardeners of Rolesville Garden Club. She lives in Rolesville, where she gardens with three dogs and a cat.
Photos by Frank Eagles