Pelargonium stock plants are grown in Israel from July - April for purposes of exporting cuttings. During this period, environmental conditions change due to seasonal variations. Stock plant nutrition influences the growth, yield, and quality of cutting. The purpose of this study was to define the N concentration required for optimum production of cuttings, and to evaluate the effect of NO3:NH4 ratios and temperature, on cutting production and quality in two Pelargonium zonale cultivars: 'Empress' and 'Rubin'. Temperature treatments consisted of ambient temperature of the greenhouse and controlled temperature of growth chambers, simulating low and high temperature conditions. The nitrogen concentration for optimum cutting production was found to be between 100 and 200 mg N liter-1. Cutting quality is affected by temperature and the N-form applied to the stock plant. A high proportion of NH4 is favorable at low temperatures, while at high temperatures, high proportion of NO3 is preferred.
