How to Stratify Seeds

Stratification is a process that some seeds require to break their dormancy period. It requires a period of a cold, moist environment, which most seeds experience during the winter. But, if you're concerned that your winter might not be cold enough or that your seeds might be stolen by birds or other scavengers, stratification can be replicated inside.

Soil, preferably a seed starting mix

Water

A small container such as a small, plastic resealable bag or small, hard plastic container

Seeds that require stratification

Plastic wrap

Refrigerator

Biodegradable seedling pot (optional)

Moisten soil until all soil is wet.

Squeeze out excess water.

Fill sanitized small container with the previously moistened soil – can be small, plastic resealable bag or small hard plastic container.

Note: Hard plastic container is easier and safer for the seeds in the long-term but does take up more room.

Sow seeds. Make sure they are covered with soil. Check seed packet for depth if sowing in a hard container.

Seal container – close bag or plastic wrap/lid on hard plastic container

Note: Plastic wrap makes the process easier in the future

Place in refrigerator in safe place where it will not be disturbed but also not where it will be forgotten.

Leave the seeds in the refrigerator for 3-8 weeks, exact amount of time should be specified on seed packet. Make sure to check moisture regularly.

After the specified length of time, remove the seeds from the refrigerator and place in a warm, indoor area. Many seed packets will specify an ideal germination temperature range, or you can look it up; it varies depending on the plant. 

If you used a plastic bag for stratification, transfer the seeds and soil to a container for germination, making sure the seeds are at the proper depth. 

Note: Using a biodegradable seedling pot is helpful when it comes time to transplant as you don’t have to worry about harming roots.

Cover the container with plastic wrap until the seeds have germinated. This helps maintain moisture in the soil. Check moisture regularly.