Rooting Softwood Cuttings of Leyland Cypress Outdoors Under Shade

Stem cuttings of Leyland cypress [x Cupressocyparis leylandii (A.B. Jacks. & Dallim.) Dallim. & A.B. Jacks], were rooted to determine the effect of A) date of collection, rooting substrate, and mist frequency, B) auxin formulation and concentration, C) rooting substrate, D) substrate fertility, and E) type of cutting and auxin concentration. Results were best for misting intervals of 5 to 7 min during the day, but 10 min was also adequate. Rooting was comparable for softwood cuttings collected in late May or late June. Powder and liquid auxin formulations, which both contained indolebutyric acid (IBA), yielded similar results. Cuttings that were more lignified (light tan color) at the bases benefited the most from higher concentrations [≈ 8000 ppm (0.8%)] of IBA in talc, whereas less mature cuttings (green at the bases) rooted in highest percentages with lower concentrations [≈ 3000 ppm (0.3%)]. Rooting was similar in substrates with a peat:perlite ratio (v/v) of 1:1, 1:2, or 1:4, whereas results were less satisfactory in 100% perlite. Controlled release fertilizer [1.8 kg/m³ (4 lb/yd³)] in the rooting substrate did not affect rooting percent, but greatly increased root mass and quality of rooted cuttings. Doubling the rate resulted in little additional improvement. Rooting was comparable for vigorous side shoots (1st-order laterals) and tips from vigorous upright branches (primary axes) of similar maturity.