Keep your perennials blooming all season long

When we are walking down the aisles of our favorite garden center, it's hard to resist the flowering perennials. With so many different types of flowers and textures in a wide range of colors, we succumb to their temptations, and they manage to find their way onto our carts. We take them home, plant them with the utmost of care, and continue to nurture them. They bloom their hearts out, the blooms fade, and then …

Here are a few maintenance tips you can easily use to keep your perennials looking good the whole season. The first, and most basic tip, is deadheading. This is simply the practice of removing the spent flowers. The main goal of annual plants is to flower and set seed, so we deadhead them to prevent them from producing seeds and then dying. By cutting off the flowers before the plant produces seeds, it can expend its energy producing more flowers.

Perennial plants, however, have well-developed root systems that carry them through the winter, allowing them to bloom once or twice during the growing season. By deadheading perennials, we can coax them into blooming again and keep them neater at the same time.

Some flowering perennials respond better than others to deadheading. To encourage a second wave of blooms or to prolong their bloom time, deadhead plants like yarrow (Achillea), coreopsis, bee balm (Monarda), coneflowers (Echinacea), phlox, campanula, pinks (Dianthus), blanket flower (Gaillardia), daisies, balloon flower (Platycodon) and speedwell (Veronica).

Toward the end of summer when cooler temperatures are alerting plants to prepare for winter, stop deadheading perennials with beautiful seed heads, like coneflowers, to provide fall and winter interest and a snack for birds.

While there are lots of perennials with attractive seed heads, others will look better if they are deadheaded. This group includes hollyhocks (Alcea), lady's mantle (Achemilla mollies), anemone, goatsbeard (Aruncus), day lilies (Hemerocallis), coral bells (Heuchera), hosta, iris and peonies. Some of these, like peonies, iris and hosta, will not rebloom as a result of deadheading, but removing potential seeds redirects the plant's energy into the foliage for the rest of the season.

Another method to get more blooms is cutting back. Instead of just removing spent flowers, cutting back involves removing a significant part of the foliage as well. It reduces 'legginess' and encourages a new fresh flush of growth.

Perennials like salvia, yarrow, goldenrod (Solidago), obedient plant (Physostegia) and foxglove (Digitalis) can be cut back to their basal foliage - the lowest portion of foliage close to the ground.

Other plants can handle the removal of most of their foliage to promote new, tidy growth for the rest of the season. Shear back perennial geraniums and cut back the fans of day lilies. You'll be rewarded with beautiful new foliage. Be sure to water plants after they have been cut back to reduce stress and boost their comeback.

Cutting back is not always done after a perennial has bloomed. Plant height and bloom time can be altered by cutting back earlier in the season. By removing about a third of the top part of stems, the plant develops two stems at each cut, resulting in more flowers on shorter stems. Bloom time is also delayed. The earlier in the season a plant is cut back, the less delay there will be in blooming.

All stems can be cut down to the same height, or cut the outer stems back further than the center stems for a softer, rounder shape. Plants that respond well to cutting back include asters, yarrow, artemisia, boltonia, bee balm, Russian sage (Perovskia atriplicifolia), phlox, turtlehead (Chelone lyonni), goldenrod, obedient plant and cardinal flower (Lobelia).

Some perennials that should not be cut back include lady's mantle, astilbe, delpimium and foxglove. If you accidentally cut back plants that won't bloom as a result, most will forgive your indiscretion over winter and bloom for you again the following year.

Deadheading and cutting back are skills every gardener should have. With a little practice and permission to make a few mistakes along the way, even beginning gardeners can learn to tend their perennials like experts.

• Diana Stoll is a horticulturist and garden center manager at The Planter's Palette, 28W571 Roosevelt Road, Winfield. Call (630) 293-1040, ext. 2, or visit planterspalette.com.