In the Garden:
New England
May, 2012
Regional Report

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As each Shasta daisy blossom fades, I'll deadhead it by cutting back to the next lower bud. When all the flower buds on a stem have flowered, I'll cut the entire stem back to the clump of leaves at the base of the plant.

Perennial Pruning

Are you getting ready to retire your pruners for the season now that spring is past? Don't put them away just yet! Sharpen those blades and prepare to continue with pruning in your flower garden.

When we think of pruning, most of us think about clipping woody plants. We think of cutting back and shaping shrubs and hedges or removing branches from trees. But pruning some of the herbaceous perennials, or what we commonly call flowering perennials, can improve their flowering and performance in the garden.

Most gardeners already do some sort of pruning of their flowering perennials, even if they don't use that term. Clipping off fading flowers, or deadheading as it is also known, is a form of pruning that will, in many cases, extend the bloom period of a plant. By cutting off the fading flowers before they can set seed, you encourage the plant to keep forming new flowers in an attempt to complete its life cycle -- that is, form seeds.

Depending on how flowers are produced, there are different ways to deadhead a plant. Many perennials, like Shasta daisies, bee balm, peonies and veronica, are simply cut back to the next lowest flower or flower bud, which will open in turn. Otherwise cut back to the next lowest leaf. If there is a clump of foliage at the base of the plant, as with Shasta daisies, globe thistle and baby's breath, cut back all the stalks that have finished flowering to these basal leaves.

Sometimes there are simply too many flowers on a plant to cut them all back individually. In this case, you can shear the entire plant back by about a third when a majority of the flowers have faded. This is a useful strategy for coreopsis, catmint, and hardy geraniums.It is also a good way to neaten up spreading spring bloomers such as creeping phlox and perennial candytuft (Iberis) after their flowers have gone by.

There are a few flowers that produce new flower buds alongside the faded flowers on the same stalk -- balloon flowers (Platycodon) and peach-leaf bellflowers (Campanula) are examples. For the tidiest look, you can carefully pinch off the individual flowers as they fade, until all the ones on the stalk have gone by, then cut the entire stalk down. Using a small pair of scissors rather than hand pruners makes it easier to get in and remove the fading flowers without injuring the still-unopened buds.

So far, we've talked about pruning after the flowers have formed. But you can also prune some plants before they flower to control their height and lessen the need for staking, or to stagger or delay bloom times. This works best with perennials that flower in the late summer or fall. For example, fall-flowering asters, which often grow tall and rangy, can be cut back by about half in early summer when the plants are 12-16" tall. The plants will bloom just a little later in the season, but on shorter, sturdier plants. If you cut back the stems on the outer edges of the clump lower than those in the middle, the foliage on the lower stalks will help to hide the "bare knees" that asters often develop. If you cut back only some of the stems of in a clump, you can have a longer season of bloom as the pruned stems come into flower after the unpruned ones.

So get out those pruners and do a little clipping in your flower garden this season. For your efforts, you'll have a neater, more floriferous garden to enjoy.

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