In one aspect, a method is provided for producing stratified fleet cotytedonary conifer somatic embryos. The method comprises (a) incubating a culture comprising immature conifer somatic embryos in a culture vessel comprising a development medium having an osmolality in the range of from 300 niM/Kg lo 450 rriM/Kg at a temperature of from 22°C to 25°C for a firs! incubation period sufficient in length for at least a portion of the embryos to reach anatomical maturity: and (b) subjecting the embryos in the culture vessel in accordance with step (a) to a temperature of from 0°C to 10°C for a second incubation period of at least one week lo produce stratified cotyledonary somatic embryos.
