Dig up the entire root system using a spade or spading fork - including all the soil from about 6 to 8 inches around the roots.
Step2
Separate the root clumps with your hands by shaking off excess soil and pulling the roots apart into divisions.
Step3
Separate tightly growing clumps with two forks. Stick them between clumps with their back sides together, then push the handles apart.
Step4
Replant the new divisions in the ground, or plant them in containers filled with soil mix.
Step5
Water new plantings well until soil is completely moist.
Step6
Discard the oldest section at the center of the clump if it looks woody and has little new growth.
Dividing Single-Stem Perennials
Step1
Use the following method for perennials that have runners (underground stems) and those that spread by growing roots through the soil and sending up more stems above ground.
Step2
Plunge a shovel or spade straight down into the soil between groups of upright, stems that are above ground. This separates the whole plant into sections.
Step3
Dig up a clump of soil that has roots and three or four stems growing out; dig about 4 or 5 inches down. These are your new plants.
Step4
Replant or pot the extra divisions.
Step5
Refill the original hole with compost.
Step6
Water the remaining plant and the new divisions well, until the soil is completely moist.