Dividing your perennials will increase your garden stock and rejuvenate older plants, keeping them vigorous and blooming freely.
Most plants should be divided every three to five years. Dig and divide coneflowers, garden phlox, foxgloves, Shasta daisies, day lilies, coreopsis and other spring/summer-blooming plants in the early fall to enable their roots to become established before winter.
Ten easy division steps to follow are:
- Lift the plant to be divided, taking care not to damage the roots.
- Gently shake off loose soil and remove dead leaves and stems.
- Separate plants using your hands, a garden spade, fork, or knife.
-
Discard the center of the clump if weak and woody.
- Divide the vigorous plants into clumps of three to five shoots each.
- Bearded irises should retain a few inches of rhizome and one fan of leaves, trimmed back halfway.
-
Prepare your garden soil by adding compost, peat moss, or aged manure, along with a light
application of super phosphate or bone meal.
- Replant the divided sections to their original depth.
- Label your new plants and water thoroughly.
- Apply winter mulch after the soil temperature drops following several killing frosts.
Dividing your perennials is an easy and inexpensive way to gain additional plants for your garden or to share plants with friends.
Divide perennials when plants are dormant just before a new growth season. Be sure to retain sufficient rhizomes, tubers, or roots. These will supply the immediate nutritional needs of the divided plant until it can establish roots. Perennials such as Shasta daisies, hostas, chrysanthemums, hardy ferns, and some herbs are easily lifted and separated in the spring.
Lift the plant and cut the stems and roots with a sharp knife. Clumps should include vigorous parts from existing plants. Replant immediately in the garden or in containers. By potting divisions, they can be given extra care while you decide where to place them in the garden. Water well after planting. Watch for signs of disease and treat if necessary.
Kathy Ballow, Smith County Master Gardener
Herbaceous perennials are plants that live in the garden from year to year. The tops usually die to the ground and emerge in the spring from buried roots. When mature clumps of Perennials grow thick and performance declines, it's time to divide them into smaller clumps or individual plants.
Dividing perennials in the season opposite their blooming is a general rule. Divide summer bloomers in either fall or spring. Prepare beds for new plants ahead, adding organic matter and fertilizer. Dig clumps and heel in while soil is improved for replanting. Replant as soon as possible.
Cut away the woody or hard, unproductive center of the old plant, using shoots only from the outer part of the clump.
Large overgrown clumps can be dug and cut into smaller sections with a spade.
Apply mulch only after several killing frosts and remove it as soon as growth begins in the spring.
Jackie Hope, Smith County Master Gardener
It's been four years since I divided my daylilies and irises. I got a late start this past fall and I've always been told to divide them in the fall; so I did. However, a number of things which prevented me from planting them immediately occurred, so I put them in a #3 washtub and put some water on them to keep the roots moist. When dividing your daylilies, look for the individual fans and cut between them. Irises are a bit easier in that you will have a new rhizome to cut off from the old one. Prepare the area where you plan to plant them by applying organic matter or compost, dig your holes, place a little bit of bone meal in the hole, and put some dirt over it. Never let the bone meal directly touch the bulb.Make a small mound in the center of the hole to fit the daylily roots over. For irises, plant the rhizome close to the surface, just barely covering the rhizome with soil.
In the middle of this project, I went to a seminar and found out that daylilies and irises can be divided any time of the year. If you divide during the blooming season, they will be set back for one season only. This was welcome news to me, as I had been changing water on those plants daily for almost four weeks. They have all been planted and are doing well, but it is nice to know that if time doesn't permit you to divide in the fall, others times of the year will work quite well. Daylily and iris farms divide plants in all but the hottest parts of the year. I still have one bed to dig and divide, and I am going to wait until March when the weather is a bit warmer.
Carol Runnels, Smith County Master Gardener
Texas Cooperative Extension
Annual & Perennial Flowers Index
Gardening Tips For Northeast Texas Index
East Texas Piney Woods Gardening Home Page