Vegetative propagation of Symphytum officinale L. (comfrey) by root cuttings

The cultivation of a high-performance variety of Symphytum officinale L. (comfrey) selected especially for the minimization of the content of pyrrolizidine alkaloids exclusively requires vegetative propagation to maintain its properties. Therefore, the development of effective methods for its vegetative propagation is necessary. The use of aerial plant parts as propagative material is not effective. The aim of this study was to examine the vegetative propagation of comfrey by root cuttings. In April and July 2013 root cuttings of 1.0, 2.0 and 3.0 cm length and of <0.5, 0.5, 1.0 and 1.5 cm thickness were prepared from potted mother plants, cultivated in a greenhouse and planted in 9 cm pots. After 42 days, all root cuttings that were at least 2.0 cm long and 0.5 cm thick showed roots. In addition, 87% of to cm long and 0.5 cm thick root cuttings also showed roots. Horizontal or vertical placement of cuttings in the pots had no influence on rooting rate.