Host a Plant-Swap Garden Party
Divide perennials in springtime if they bloom after mid-June. Choose plants that are full or overgrown. Some good options: bee balm, aster, astilbe, black-eyed Susan, blanket flower, campanula, chrysanthemum, coreopsis, daylily (after they bloom), hosta, phlox and ornamental grasses.
Don't divide plants in spring that are bulbs, new to your garden or very young. Plants that bloom in spring are better left until late summer or fall to divide. Some plants do not respond well to being divided, such as columbine, bleeding-heart and ferns.
Preserve root balls by digging 2-4 inches away from them as deeply as you can. Pop out the plant, then divide roots by hand. (For difficult roots, slice a spade through the middle.) Immediately replant one section; wrap the other in moist paper, keep cool and plant as soon as possible.