Steamboat Pilot & Today

Steamboat Springs — If you have an established garden with perennials, bulbs or shrubs, chances are you'll need to divide and replant some of them to control their size or rejuvenate them. After three to five years, most perennials will stop flowering and crowd themselves into an unruly mass of leaves and roots.

Each rooted segment of a plant is capable of becoming a plant in itself. By dividing the plants when they are dormant, you keep them strong and healthy. And you increase your inventory of plants for other areas of the garden or gifts to gardening friends.

Signs that your plants may need dividing include production of fewer or smaller flowers, hollow or dead centers in your clumps of plants or lower parts of plants losing leaves and looking scraggly.

Now is the best time to divide plants that bloom in late summer and fall. Plants that bloom in spring and early summer should be divided in early fall so roots have a chance to grow some before winter sets in. Pay attention to plants coming up in the next couple of months and make notes of which ones need dividing in early September.

Here's how to do it:

First prepare the area where you want to grow the newly divided plants. A day or two before you divide your plants, water the plants and prune the stems and foliage to about 4 to 8 inches from the ground. This will make it easier to lift out the parent plant and avoid too much moisture loss. A cool, cloudy day for dividing and replanting is best.

Try to lift the entire clump from underneath. If it's too heavy, use your shovel to cut it into several pieces before lifting it out. Hose off the loose soil and remove any dead foliage so you can better see the roots.

For plants with root systems, simply pull the clump apart with your hand, a knife or digging fork. If the roots are really tough, you may need to use a saw or an ax to divide the plant. Throw away any weak or woody sections. If you want larger plants right away, keep several buds or shoots with each division for replanting. Your healthiest divisions will come from the outside of the clump.

For bulbs, corms, rhizomes, tubers and tuberous roots, each division should have a section of the original stem and a bud.

Keep all divided plants moist until you replant at the same depth as they were originally. Water well and mulch.

Some plants resent being disturbed and should not be divided. These include monkshood (Aconitum), false indigo (Baptisia), bleeding heart (Dicentra), lupine (Lupinus), columbines (Aquillegia), peony (Paeonia) and poppy (Papaver). Lavender, rosemary and several artemesias also should not be divided, although you may cut branches with roots from the parent plant and replant those to increase your stock of those plants.

Dividing perennials is an easy and inexpensive way to add plants to your garden or to share with friends.

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