Anyone can propagate plants from their perennial garden. It’s practical, inexpensive and fun. If you are fortunate enough to already have some perennials, why not make some more? To produce plants identical to the ones currently in your garden, they must be divided or have cuttings taken. Plants grown from seed are often not true-to-type.

So, what plants should you divide? It’s best to divide clump forming plants. Avoid trying to divide plants with tap roots. Division should be done in early spring unless the plant is a spring bloomer—then wait until after bloom. Dig up the entire plant, gently untwine the roots and slice the plant into smaller sections. Discard the older center and plant out the “babies” in well amended soil and keep moist until established. This procedure can be used with iris after they have bloomed. Most clumping perennials need division every three to four years. Usually when the center of the plant dies or the plant stops blooming, it’s a sign that it needs to be divided.

Propagating from seed will produce an abundant amount of plants and create more diversity. There are local seed companies to purchase seed from or collect seeds when the seed pod is dried. Some plants, like delphinium, need darkness (in the form of a soil covering) to germinate, while others, like columbine, need light. A rule of thumb is to cover seed with the same depth of soil as the seed height—tiny seeds are barely covered.

Depending on the species, some seeds need a chilling period called stratification. To stratify, mix the seed with a small amount of peat-based seed starting mix and put the mixture in the refrigerator for two months. You can also sow the seed outside in the fall or plant seed in pots and keep them in a cool garage—make sure to keep the soil slightly damp. Seeds that need stratification are butterfly bush, butterfly weed, callirhoe, campanula, columbine, delphinium, desert four o’clock, liatris, lupine, penstemon and thermopsis, among many others. Sometimes hydrogen peroxide is used to soak seed after stratification to aid in germination. Pot up seeds after the chilling period and grow the plants. When the plants are large enough, acclimatize them to spring outside temperatures and plant out.

Plants that do not need a chilling period to germinate may be started in spring or early summer by planting seeds in amended garden soil. Perennials that do well planted in spring are achillea, agastache, aster, chocolate flower, coreopsis, echinacea, gaillardia, blue flax, monarda, Missouri primrose, sand penstemon, Mexican hat, blue sage, stonecrop, spiderwort and Joe Pye weed.

An excellent resource for perennials for Colorado is Perennials for the Rocky Mountains and High Plains by James E. Klett, PhD and Celia Tannehill. This book is available from the Colorado State University Resource Center or your local Extension Office. It has some information on propagation. Also, CSU Extension Fact Sheets #7.221, “Seed Storage” and #7.231 “Xeriscaping: Garden Flowers,” are excellent resources. Many seed catalogs also explain how to propagate their products.

Propagating perennials does not require any special equipment, is fun and easy to do. Just plan ahead—in a couple years you’ll have a beautiful perennial garden. With perennials it’s important to remember that the first year they sleep, the second year they creep, and the third year they leap—so get out there and divide and conquer!

The authors have received training through Colorado State University Cooperative Extension's Master Gardener program and is a Master Gardener volunteer for Larimer County.

Gardening and Insect Fact Sheets are available on-line by clicking HERE.

Return to Master Gardener Articles

This page updated:  August 27, 2007