Taking Perennial Root Cuttings
Root cuttings are a good way to propagate perennials with thick fleshy roots. The cuttings can be left outside during winter, although standing them in a coldframe is preferable.
2. Select young, vigorous roots of pencil thickness and cut them from the parent plant near the crown.
3. Cut each root into 7-10cm lengths, cutting straight across the top and slanting at the bottom (so you know which way to plant them).
4. Fill a deep 13cm pot with moist cuttings compost. Insert six to eight cuttings around the rim, 2-5 cm apart, their tops level with the soil surface.
5. Cover the compost with a fine layer of grit and place the pots in a coldframe, a sheltered place outdoors, or on the windowsill of a cool room.
Perennials that can be raised by root cuttings include: acanthus, Anchusa azurea, Japanese anemone (Anemone x hybrida), gypsophilia, oriental poppy (Papaver orientale), verbascum.
In spring or early summer, when leaves appear, pot the cuttings up individually and grow them on for planting outside in autumn or the following spring.
After taking the cuttings, replant the parent plant immediately. The soil can be improved by forking in some well-rotted organic matter before replanting.