Book excerpt: Commercial nurseries have struggled to meet the demand for grafted cuttings of the rootstock UCD GRN-1 due to difficulties during the rooting stage of propagation. Viticulture staff at the University of California, Davis - where GRN-1 was bred - have no such difficulty propagating it. The aim of this study was to identify the critical factor(s) that lead to the successful propagation in one setting and not the other, and to make practical recommendations for commercial nurseries. Over the course of two years, multiple trials were conducted to evaluate the effects of different treatments and collection protocols on the propagation of GRN-1 and several other comparison rootstocks. During the first year, many treatments were tested, and the results were used to inform deeper examination of only a few treatments in the second year. Successful treatments included: collecting cuttings either very early or very late in the dormant season, incubating cuttings in warm conditions prior to grafting, and allowing cuttings to grow over longer periods of time. In addition, the graft compatibility between GRN-1 rootstock and a Vitis vinifera scion was tested and no evidence of incompatibility was found.