Dividing perennials every three to six years is a great way to thin clump-forming varieties, like the daylily (shown here), which blooms from late spring to late summer. This technique can also be used to control plant size, invigorate growth, and multiply the number of specimens in a garden. A good rule of thumb is to split apart spring- and summer-blooming perennials in late summer or before the fall frost. Cost:
See How to Divide Perennials
for sull step-by-step instructions. And don't forget to check out How to Get More Plants at No Cost
for even more ways to multiply the plants you've already got.