Ornamental shrubs: Effects of stockplant management on the rooting and establishment of cuttings

Summary

The majority of ornamental shrubs are produced vegetatively, through leafy cuttings. For a number of commercially important species difficulties in rooting, overwintering and subsequent establishment of cuttings lead to inconsistent production. Why some species remain difficult to produce from cuttings, even when a highly supportive propagation environment is used, requires investigation. Experiments with a range of ornamental shrub species indicated that stockplant pruning could strongly influence cutting performance. Harder pruning significantly increased percentage rooting in Syringa and enhanced winter survival of Corylopsis, but decreased rooting and survival in Acer.In Syringa, rooting was closely related to shoot growth, and the retention of an active shoot tip on the cutting was important. Results suggested that shoot growth on the excised cutting was a better indicator of rooting potential than shoot growth on the hedge before cutting collection. In addition to influencing subsequent shoot vigour, bud position on the mother plant could affect rooting (Syringa) or winter survival (Rhododendron) directly. For certain species, factors associated with the early stages of propagation appeared to determine final establishment rates, even though initial rooting percentages were unaffected.