As we turn the corner and head into the next gardening phase, fall is a good time to complete several late season chores. Fertilizing and overseeding lawns, planting spring flowering bulbs and dividing perennials are all tasks that can be easily completed during these mild September days. So if your perennial bed is in need of a fresh new look, take a few minutes to rejuvenate the old spindly plants and start again new.

There are several reasons for digging and dividing perennial flowers. Old plants can become weak and be poor bloomers. They can outgrow their space and need to be downsized. Over time, grass and weeds can infiltrate entire beds, making it difficult to keep clean. Or maybe you just want to share a piece with a friend or neighbor as a way to say thank you or welcome to the neighborhood. Whatever the reason, now is a good time to dig and divide certain perennials.

As a general rule of thumb, plants that bloom in summer can be divided in spring or fall. Plants that bloom in the fall should only be divided in the spring. Specifically, now is a good time to divide astilbe, beebalm, black-eyed Susan, cranesbill geranium, day lily, peony, garden phlox, hosta, lambs-ear, purple coneflower, coreopsis and yarrow. Plants that should not be divided now include chrysanthemums, sedum, aster, blanket flower, bleeding heart, ornamental grasses and wormwood artemisia.

Begin by laying down a tarp to protect the grass and have a movable container such as wheelbarrow or bucket. These will provide a place to set the plants once dug. Dig and lift the plants with a potato fork or spade, starting about 6 to 8 inches from the outside edge of the clump. Work around the clump, loosening and lifting, being careful not to damage the plant or its roots. Smaller plants can be dug with less of a root ball. Once the plant is lifted from the bed, the clump can be divided using a sharp saw, knife or two spading forks placed in the middle of the clump and pulled apart from opposite directions. The tool used to divide the plant will depend on the type of plant. Tubers need to be cut, while open-centered plants are best divided with the spading fork. Although three to five bud eyes or shoots are adequate for a division, the smaller divisions may delay blooming and establishment. Larger divisions work better in the fall.

Store the dug plants in a cool, shaded area while you take time to work the bed, hand-weed and amend the soil. If several days are needed to complete the renovations, keep the dug plants moist but not soggy.

Before replanting, remove dead or damaged plant and root parts. Then dig an adequate-sized hole for the root system, spread the roots out evenly, and reset the plant. Make sure the plants are reset at their original depth. This is especially important for peonies and iris, as planting too deeply results in a failure to bloom. Avoid compacting the soil, but rather water in the newly set plant well and let the soil melt in around the roots. Cut the tops back to reduce the amount of plant area the roots must support. Generally, a little more than halfway will suffice for most plants. Small divisions may need protection from sun and wind for the first few days. Apply a 2-inch layer of organic mulch to help the soil retain moisture around the roots and insulate the soil, allowing time for establishment before winter.

Want to learn more about digging and dividing perennials in the fall? Join the Extension Master Gardeners and myself at the Fall Garden Festival from 10 a.m. to 2 p.m. Saturday at the Douglas County 4-H Fairgrounds.