Dividing perennials gives flowers new life

ONE ATTRACTION of perennial flowers is their perennial nature. A single planting will last for years.

But “perennial” doesn’t mean the plants never need any care. With age, some perennials spread to form clumps whose centers die out as new growth pushes out at the edges. The crowns of other types of perennials inch upwards out of the ground each year, eventually dying from exposure to the elements. The result, in either case, is less flowers. When this happens, it’s time to divide the clump, and now or soon is usually the time to do so.

Wait until you see new, green growth in spring before dividing a perennial clump. Then the more exuberant, young growth, which is what you are going to save, will be obvious. Don’t wait until growth has become rampant in the spring, though, or the plant will be shocked by this rough treatment.

To divide a clump, work around its edge with either a shovel or a spading fork, thrusting the tool into the ground at an angle to get under the clump. Push down on the handle to lever the clump up and shake dirt loose from the roots. Eventually, the clump will be sitting on top of the ground.

Before you separate a clump, cut just the crown — not the roots — into pieces with either a pruning shears or a sharp knife. Next, separate the crown pieces, teasing apart their attached roots. Use your hands. Or use two garden forks back to back in the center of the clump, then pulled apart at their handles. Save for replanting the vigorous, young crown pieces that grow along the outside edge of the clump. Until they are replanted, keep these crown pieces covered with moist burlap or soil. The one opportunity to improve the soil beneath perennials is when the plants are divided, before replanting. Phosphorous is a plant nutrient that moves very slowly in the soil, so mix a handful of bone meal in the planting hole to ensure a good supply of phosphorous right near the roots. Also mix limestone, if needed, into that gaping hole.

Next, build a mound of soil in the planting hole on which to set the crown. Adjust the mound’s height so that when the soil is firmed the crown will be at ground level. Then fill in the hole, sifting soil in around the roots. Spread a layer of sawdust, shredded leaves, or compost over the ground as mulch, and slowly water the plant in with a gallon of water. To look their best, some