Although seeds are generally accepted as nature’s way of ensuring the continuation of a species in the plant kingdom, there are other ways of propagating garden plants. Most plants propagated in horticulture are grown asexually by cuttings, budding, grafting or from tissue cultures. This month we feature plant propagation by means of root cuttings, a simple and efficient way of producing more perennial plants with soft, fleshy roots. Examples include Acanthus mollis (Bear’s breeches), Phlox paniculata (Perennial phlox) and Anemone japonica (Japanese anemone). This practice is usually carried out in late winter when the plants are dormant or in early spring but, in the case of Acanthus, it’s done in summer.
Step 1: Dig up the entire plant or, alternatively, remove suitable roots from plants growing in the garden. The best roots are thick (preferably thicker than 5mm in diameter) from close to the crown of the plant.
Step 2: Wash off all excess soil or growing medium from the roots.
Step 3: Trim off all fine or fibrous rootlets, leaving only the thick fleshy roots. Cut these into sections 5-10cm long in the case of thick roots and 7 – 12cm long if the roots are thin and wispy.
Step 4: Place these sections of root into a medium of equal parts of river sand and peat in a deep plastic tray.
Step 5: Cover the roots with the same growing medium (sand and peat) to a depth of 10 – 15mm. Firm down with a wooden stamper. Water well to allow the root cuttings to settle snuggly into the rooting medium.
Step 6: Place the tray of root cuttings into a propagating frame or store it in a shaded part of your garden. Keep it relatively dry until growth emerges. If the rooting medium is too damp the cuttings may rot.
