Division is the easiest way to propagate herbaceous perennials. Simply dig up the plant, cut it into smaller sections and re-plant in well-prepared soil.
Ideally, perennials should be lifted, divided and re-planted every three to five years. You'll be rewarded with healthy, vigorous growth and a crop of new plants to swap or sell.
Many herbaceous perennials naturally form crowns with numerous distinct stems, which make it easy to divide them into sections. As the crown grows and develops it produces the newest, strongest shoots at its edges, the older centre is less productive and is best discarded.
Most perennials can be divided in autumn or spring or immediately after flowering.