In the wild
In the wild, seed dormancy is usually overcome by having its hard seed coat softened up by frost and weathering action during winter. This is nature’s form of “cold stratification” or pretreatment. This cold moist period triggers the seed’s embryo; its growth and expansion can then break through the softened seed coat in its search for sun and nutrients.
In its most basic form, when the stratification process is controlled, the pretreatment amounts to nothing more than subjecting the seeds to storage in a cool and moist environment. This period of time may vary from one to three months.
To accomplish this seeds are placed in a sealed plastic bag with moistened vermiculite (or sand or even a moistened paper towel), which is then refrigerated. Three times as much vermiculite as seeds is used. It is important to only slightly dampen the vermiculite, as excessive moisture can cause the seeds to mold in the bag.