Dig the entire clump and carefully separate plants.
Some plants are slow to divide, such as large, blue colored plants.
Others, may need dividing every three to four years, such as those used as edging. Copyright 1995 by the Board of Trustees of the University of Illinois. The information provided is for educational purposes only. References to commercial products or trade names do not constitute an endorsement by the University of Illinois and do not imply discrimination against other similar products.