Label the bag with the name of the seed and the date to be removed from cold. Four to 12 weeks is usual. Remove the seed and sow. Cold germinators' only sprout at cold temperatures and are most conveniently treated by layering in damp towels and pricked off as they germinate. If using outdoor treatment, hold pots at above freezing for a few weeks before putting outside.
Snow cover is highly beneficial.
Dormancy is highly variable. Sometimes a seed collected in the warm lowlands will germinate readily, but the same species collected at high elevation will need cold. Dormancy even varies between individual plants at the same site, and varies with weather conditions before harvest and conditions of storage after harvest. GA-3 is a naturally occuring plant growth regulator. Presoaking seeds in GA-3 will often cause rapid germination of many highly dormant seeds that would otherwise require cold, aging, light, or other prolonged treatments.