Dividing Perennial Flowers

Many perennials will need dividing after three years. Some perennials are best left in place and not divided; examples include: baby's breath, blue wild indigo, gas plant, goat's beard, globe thistle, and sea holly.

The best time to divide most perennials is in the spring when new shoots are 2 to 3 inches tall, or in the fall when the foliage starts to die back. Plants divided during an active growth period in the summer are slower to become re-established.

Some perennials can be divided following their flowering period even during the summer, examples include daylily and bearded iris. Division is normally done by digging and dividing the clump into several smaller clumps. An alternative for vigorous clumps is to slice off a section with a sharp spade while leaving the main clump in the ground.

Some perennials (chrysanthemums, bearded iris) exhibit a decline in vigor as a clump grows. Transplants from the clump's center often grow poorly and bloom sparsely. To divide mature clumps, select only the vigorous outer edges of the clump and discard plants from the center.

Divide the plant into clumps of three to five shoots each. Do not put all the divisions back into the same space that contained the original plant --- that would place too many plants in a given area. Exchange extra plants with a friend, plant them elsewhere in the yard, or discard them.