Vegetative propagation of cannabis by stem cuttings: effects of leaf number, cutting position, rooting hormone, and leaf tip removal

This study evaluated the influence of several factors and their interactive effects on the propagation success of stem cuttings of cannabis (Cannabis sativa L.). Factors included (i) leaf number (two or three), (ii) leaf tip removal (one-third of leaf tips removed), (iii) basal/apical position of stem cutting on the stock plant, and (iv) rooting hormone [0.2% indole-3-butyric (IBA) acid gel or 0.2% willow (Salix alba L.) extract gel]. Cuttings were placed in a growth chamber for twelve days and then assessed on their rooting success rate and root quality using a relative root quality scale. The IBA gel delivered a 2.1x higher rooting success rate and 1.6x higher root quality than the willow extract. Removing leaf tips reduced rooting success rate from 71% to 53% without influencing root quality. Cuttings with three leaves had 15% higher root quality compared with those with two, but leaf number did not influence rooting success rate. Position of cutting had little effect on rooting success or quality. To achieve maximum rooting success and root quality, cuttings from either apical or basal positions should have at least three fully expanded uncut leaves and the tested IBA rooting hormone is preferred to the willow-based product.