Over time, many herbaceous perennials form large, dense clumps. As the center of the clump gets old, flowering can decline and the plant can lose its shape. Division is a simple propagation technique that rejuvenates old plants and gives you free new ones.
The best times to divide plants are in autumn or early spring when the plant is dormant. Dig up the mature plant gently. Use two garden forks back-to-back to pry the clump apart, or use a sharp knife to cut it into smaller sections, ensuring each section has healthy roots and shoots. Replant the divisions immediately into their new homes or pots, water thoroughly, and enjoy your new plants.