Germinant quality can be manipulated simply by controlling the temperature at which the embryos are matured and by the timing and duration of the temperature treatment. Plates of maturing white spruce somatic embryos at four stages of development (I- mammilate, II- early cotyledonary, III- cotyledonary and IV- mature) were put in darkened incubators at five temperatures (1, 5, 10, 20, or 30°C) for a period of 0, 1, 2, 4, or 8 weeks. The embryos were then germinated and germinant quality was correlated with the temperature treatment. Conversion was improved by exposing plates of fully mature embryos to 5°C, or immature or mature embryos to 10°C, for a minimum of 4 weeks. Embryos grown at temperatures of 10°C and above can become vitreous or germinate precociously. To preclude this loss in quality, embryos may be stored short-term at 5°C. Stage III & IV embryos were kept for 8 weeks at a temperature of 5°C without any loss of germinant quality.