The modern method is to thoroughly mix seeds in moist peat moss. The peat moss should be barely moist to the touch. The mixture is stored in sealed containers such as polyethylene bags. The bags are simply stored at room temperature to provide the moist warm treatment. They can be placed in the household refrigerator if a moist cold treatment is required.
Moisture is obviously a key factor in the stratification process.
In theory it is possible to increase the amount of moisture in the peat moss to speed up stratification. High moisture levels in the sealed containers, however, causes fungus growth that can harm the seed. Seed stratification can be a rewarding technique for the amateur to try. Stratify for 3 months at room temperature, then for 4 months in the refrigerator. Sow in the spring.