stratification

Placing seeds into cold temperatures for a defined period of time to simulate winter conditions. Stratification is required by some seeds to stimulate germination. Many temperate plant species developed the requirement for an extended exposure to cold weather to prevent their seeds from germinating during a mid-winter thaw and then being killed off by subsequent frigid winter temperatures.

Some species require wet stratification to prevent the seeds from drying out during its dormant treatment. Use damp sand or peat moss to prevent rotting seed.