Perennial Flowers: Propagation

Starting Plants from Seeds
If you plant seeds, some off-types of color, flower form, and plant habit can be expected. Perennials seeded in the garden frequently fail to germinate properly because the surface of the soil crusts and prevents entry of water. To avoid this, sow the seed in vermiculite-filled furrows. While you can sow perennial seeds directly in beds where they are to flower it is usually best to start plants indoors or in a cold frame and set them outdoors after the weather warms. An alternative to spring seeding is to sow seeds in flats or seedling beds during the summer for fall transplanting. Perennials started in spring frequently will not flower their first year.

Dividing
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 reestablished. 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.

Consumer Horticulture | Perennials Home

Prepared by: Erv Evans, Consumer Horticulturist, NC State University