Deadheading and pruning perennials keeps plants beautiful

  • Remove spent flowers of yarrow and the reward is a second flush of blooms.

    Remove spent flowers of yarrow and the reward is a second flush of blooms. Courtesy of Diana Stoll

 
By Diana Stoll
Posted7/5/2020 7:00 AM

Deadhead and prune perennials for several reasons. First, deadheading encourages plants to continue blooming or rewards the gardener with a second season of bloom. Next, removing spent flowers from prolific self-seeders prevents them from spreading their progeny across the garden.

Deadheading and pruning also give gardeners a head start on fall cleanup. And finally, they keep the garden looking its best all summer long.

                                                                                                                                                                                                                       
 

Columbines, many campanulas, dianthus and foxgloves are spring bloomers that reliably rebloom if deadheaded. Summer blooming perennials that rebloom if deadheaded include catmint, coreopsis, coneflowers, phlox, salvias and veronicas.

Roses respond beautifully to regular deadheading. If the flowers are held in a cluster, nip individual flowers as they decline, and when the entire cluster is spent, cut the stem back to the first leaf structure with five leaflets.

Some perennials will only bloom once even if they are deadheaded but removing faded flowers improves the overall health of the plant and makes the garden look more manicured.

Prune perennials that are summer worn or have grown leggy. Aggressive shearing may encourage fresh new foliage on more compact plants and another round of blooms. These bonus floral displays are usually smaller and less dramatic, but welcome just the same.

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Plants that grow from bulbs and rhizomes should be deadheaded to ensure lavish bloom in subsequent years. Because flowers are essentially seed-making machines, allowing seeds to form and reach maturity depletes the nutritional resources of the bulb or rhizome. These nutrients are better used to form more and larger flowers for next year.

In addition, the old flowers of most bulb- and rhizome-produced flowers are unattractive, so you will be improving the overall look of your garden by removing these past-their-prime flowers.

The old flowers of lilies should be removed promptly, but care should be taken to make the cut just below the lowest flower. The remaining foliage should be left to help the plant build up those nutrient reserves. Only when the stem and foliage begin to deteriorate should the rest be removed.

It is especially important to deadhead German bearded iris. Nasty iris borers enter the plant through the leaves so removing lagging foliage and mushy flowers eliminates a welcoming environment for infestation. Siberian irises are not as susceptible to borers and their foliage remains attractive all summer. Deadhead these plants to promote increased flower production next year.

Deadheading and pruning perennials may not be a favorite garden pastime, but it is worth the time to keep your garden looking beautiful all summer long.

• Diana Stoll is a horticulturist, garden writer and speaker. She blogs at gardenwithdiana.com.

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