Scrape the soil away from the outside of the crowns and carefully detach a few roots.
With potted plants; remove plant from pot and tease out a few suitable roots for propagation.
Cuttings can be taken at most times of the year providing the soil is not frozen.
Pencil-thick woody roots should be cut into 40-50mm (2") sections then inserted vertically into the compost, ensure that they are the correct way up.
Thinner / Fleshy roots should be cut into 50-75mm (2"-3") sections and laid horizontally on the compost surface then lightly covered with compost.
When shoots emerge in the spring, lift the young plants carefully from the compost and repot into suitable sized pots and grow on in a frost free environment until they are sufficiently established to be planted out into their final quarters.