A rugged, beautiful perennial also known as purple coneflower or purple echinacea, coneflower (Echinacea purpurea) produces white or lavender, daisy-like petals surrounding prominent, purple-brown seed cones throughout summer. The plant reaches heights of 12 to 24 inches at maturity, depending on the variety. Coneflower is perennial in U.S. Department of Agriculture plant hardiness zones 3 through 9. Although coneflower is often propagated by planting seeds or dividing a mature plant, you can also start new plants by making root cuttings when the plant is dormant in late fall or early winter.
Fill a planting container with a regular, good-quality commercial potting soil. Wet the potting soil thoroughly, then allow it to drain until it is evenly moist throughout but not dripping. Any container is suitable as long as the depth is at least 6 inches and it has a drainage hole in the bottom.
Dig a dormant coneflower plant, digging deeply to preserve as many roots as possible. Wash the roots, then select a few of the the strongest roots to propagate. Use clean pruners to cut several roots, making the cuts close to the plant, then replant the coneflower. Don't remove more than one-third of the roots from the plant. Roots with a diameter at least the size of a thick wire and no larger than a pencil are best.
Cut the roots into pieces measuring 2 inches for pencil-sized roots and up to 4 inches for narrower roots. Cut the bottom of each root at an angle, then trim the top of the root -- the part that was closest to the plant -- straight across. Cutting this way is critical because it reminds you of the proper orientation of the roots.
Make a planting hole deep enough to accommodate each root piece, using a pencil or similar object. Insert the roots into the holes with the angled side down, the straight edge facing up and the top of the roots even with the surface of the soil.
Cover the soil with 1/2 inch of coarse sand or grit. Place the pot in a cold frame. Alternatively, cover the pot with a plastic bag and place it in a shady, protected location. Water only as needed to keep the potting soil slightly damp.
Remove the plastic when new growth appears on top of the roots in spring. Remove the roots carefully from the container with a table knife or similar object. Plant each root in a 3-inch container filled with regular potting soil. Return the pots to a sheltered location and continue to keep the potting soil slightly damp.
Transplant the new coneflowers into a sunny garden spot in spring when all danger of frost has passed and the plants are well established and continue to display healthy new growth.