Dividing Perennials

By Pat Dickey, Fairfax Master Gardener
Fall is the time when flowering perennials begin to show their wear from all the work they did to produce flowers during the spring and summer in your garden. Now is a good time to divide and rejuvenate them. You may want to produce more plants to share with your friends or just have more for other areas of your garden. With the exception of a few, most perennials can be divided every three to five years. Some do not want to be divided, and others can wait eight to ten years.

dead center of perennial

dead center indicates need of dividing

How can you tell whether a perennial should be divided? Its flowers are smaller than usual. There is a dead space or hole in the center of the plant. The overall growth of the perennial has been less vigorous, or it grew out of the boundary of its intended area. Also, the foliage at the bottom of the plant has become sparse and leggy.

Perennials that bloomed in the spring and summer should be divided in the fall. Those that now have flowers should wait until the spring before you divide them. You can also wait and divide some spring blooming perennials in April or May, when they have finished flowering. Just remember to divide the perennials when they don’t have flowers, so that all the plant’s energy will go to support root and leaf growth. A perennial divided in the fall needs six weeks to become established in its new permanent location before the ground freezes.

There are a few steps that you must take before dividing perennials. Check the area and soak the ground, if needed, one to three days prior to dividing. Plan to work on a cool or an overcast day. Prepare ahead the holes and/or pots for the newly divided plants. You will want to transfer the divided plants quickly so that their roots do not dry out. Gather your tools; you will need a spade or shovel, digging forks, or a sharp garden knife, depending on the type of roots your perennials have.