Deb Babcock: Propagating perennials through division

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Deb Babcock

Deb Babcock's gardening column appears Thursdays in Steamboat Today.

Find more gardening columns here.

— Every few years, my irises and tulips seem to come up smaller and shorter, with some shoots never developing flowers at all. This summer, one of my groundflower beds reminds me of my bald Uncle Dale with its bare center and leafy fringe.

These are cries for help from my garden plants telling me they are too crowded in the space I originally allotted to them. It's time to dig them up, divide the roots or bulbs and replant.

Dividing your perennials is healthy for your garden and its plants. Plus, it gives you an opportunity to fill in a bare spot with a favorite plant from another part of the garden or to give away some plants to friends and neighbors.

Right now, after the spring and summer blooming plants have completed their flowering, is a good time to dig them up and divide the root system. Be sure to have a planting area ready for immediately placing the newly divided plants back into the ground. Don't let the roots dry out, and try to give the plant as much time as possible to become established before the ground freezes. Be sure to keep the soil moist to help lessen the stress of the replanting.

When digging up perennials for replanting, use a garden fork or a sharp shovel to dig all the way around the plant, far enough from the stems to get most of the root system. Lift the plant carefully, and gently brush or shake off soil from the roots so you can see what you're doing. Hosing off the roots will help remove some of the dirt, also.

If your plant has grown too large to lift easily with the garden fork or shovel, you may need to cut it into several sections before removing it from the ground. Use your shovel, a sharp knife, or a hatchet to do this.

Next prune the stems and foliage that are closest to the ground to make it easier to see what you're doing and limit moisture loss. Remove any broken or diseased foliage and discard.

Then you can cut or break apart your plant, leaving sections of root that have at least three young shoots on each. The outer edges of your plant will have the youngest shoots and will produce the most vigorous plants. Replant as soon as you can, at the same depth as the plant was sitting when you dug it up. Water thoroughly and mulch to avoid moisture loss and keep the soil a little warmer longer into the fall.

Plants that are easiest to break apart using just your fingers include blanket flowers (gaillardia spp.), bleeding hearts (dicentra spp.), columbines (aquilegia spp.), coral bells (heuchera spp.), forget-me-not (myosotis sylvatica), hellebores (helleborus spp.), Jacob's ladder (polemonium caeruleum), lamb's ears (stachys byzantina) and pansies (viola spp.).

Other plants such as daylilies, beebalm, hostas, phlox and daisies may require cutting with a shovel or knife. And some plants require using a handsaw: astilbes, bear's breeches (acanthus spinosus), gayfeather (liatris spicata), Joe Pye weed (eupatorium maculatum), peonies (paeonia cvs.) and wild indigo (baptisia australis).

Perennials that do not fare well when divided include candytuft (iberis sempervirens), (dianthus caryophyllus), delphinium (delphinium X elatum), foxgloves (digitalis spp.), garden sage (salvia officinalis), geraniums (pelargonium spp.), lavenders (lavandula spp.), rose campion (lychnis coronaria), rosemary (rosmarinus officinalis), Russian sage (Perovskia atriplicifolia), silvermound (artemisia schmidtiana), sweet pea (lathyrus latifolius) and trillium (trillium grandiflorum).

Deb Babcock is a Master Gardener through the Colorado State University Cooperative Extension Service Office in Routt County. Questions? Call 879-0825 or e-mail gardeners@co.routt.co.us.

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