Adventitious Rooting of Lavandula x intermedia Cuttings

Due to challenges associated with lavender propagation, Texas hybrid lavender (lavandin) growers require revised propagation information. Therefore, experiments investigated effects of media and plant growth regulators (PGR) on rooting of three different lavandin (Lavandula x intermedia) cultivars. PGRs applied to cuttings were naphthaleneacetic acid (NAA), or indole-3-butyric acid (IBA) at three concentrations. In addition, four rooting media were examined. Cuttings exposed to a peat moss/sand medium had the greatest mean overall rooting percentage, number of roots, and regardless of cultivar, cuttings exposed to the peat moss/sand medium had the longest roots. In general, mean rooting data were also greatest for cuttings dipped in NAA at 0.5 and 1.0 g·L−1 (500 and 1000 ppm, respectively). Overall, across all media and PGR treatments ‘Grosso' cuttings tended to have the greatest rooting percentage and longest roots. In addition, compared to the no PGR treatment, ‘Provence' and ‘Hidcote Giant' cuttings exposed to the peat moss/sand medium and greater PGR concentrations produced cuttings with an increased mean rooting percentage and longer roots. When rooting lavandin cultivars, results indicate correct media selection, PGR formulation, and PGR concentration determine propagation success. Index words: lavandin, Lavandula x intermedia Emeric ex Loisel, peat moss, perlite, rooting percentage, root quality, sand. Chemicals used in this study: indole-3-butyric acid (IBA; 0.5, 1.0, and 1.5 g.L−1); naphthaleneacetic acid (NAA; 0.5, 1.0, and 1.5 g.L−1). Species used in this study: ‘Grosso', ‘Provence', and ‘Hidcote Giant' lavandin (Lavandula x intermedia Emeric ex Loisel.).