Garden perennials are generally considered to be relatively low-maintenance plants, but there eventually comes a time when the gardener recognizes the need for a bit of upkeep.
Fall is an ideal time to divide and conquer those overgrown perennials that have become crowded and unruly.† Moderate air and soil temperatures now favor a quick recovery and healthy root growth with a minimum of stress to the plants.
Herbaceous perennials such as coreopsis, chrysanthemum, daylilies, delphinium, iris, lambís ears, penstemon, scabiosa, Shasta daisy, and yarrow benefit from occasional division to reduce their size and stimulate fresh new growth.† Itís also an inexpensive method of propagating additional plants for your garden or to share with friends and neighbors.
Select the plants to be divided and prepare them by giving them a moderate pruning.† Pruning reduces the amount of leaf surface and limits transpiration, which will deprive the new plants of needed moisture at a critical time.† The first step is to carefully dig around the plant to be divided, leaving as large a soil ball as possible.† Lift the clump gently from the ground.
Next, divide the main clump into several smaller clumps along the obvious separation points.† Often you can gently tease the roots apart and separate the clump into smaller sections.† However, if the clump is seriously overgrown and the roots are badly tangled, you should pry the roots apart using two spading forks.† Insert one fork into the center of the clump, then insert a second fork back-to-back with the first and gently separate the roots.† Repeat to separate further again.
Discard the older, less vigorous portions of the clump and save the newer, healthier divisions for replanting.† Healthy roots should have a white, sturdy appearance.
Replant the newly divided plants directly into the garden.† Prepare the area to be replanted by amending the soil with compost or other organic material to ensure that new plants become established quickly.† Plants may also be potted up into containers for sharing with others.† Water plants thoroughly after planting.† Follow up a week later with a light liquid fertilizer application.† Provide protection from too much sun, wind, and extreme temperatures.