Stratification of seeds is the process of exposing seeds to cold conditions in order to encourage germination.
The exact process you choose (there are two options) depends on the flower variety you’re growing. Let us explain! The different processes are defined below.
Planting in Fall
If time is not a problem, nature itself can cold stratify your seeds. Just place them in the ground in fall and let them go through a winter. They will sprout next year, but not flower. The following year, having gone through two winters, the flowers will return and bloom as expected. Some varieties like poppies and coneflowers will bloom the first year.
Creating a False Winter
The second way to cold stratify seeds (especially if you want to save time!) is to create a false winter. This method tricks the seeds into thinking they have been in the cold ground, when they’ve actually been chilling in your refrigerator. The refrigeration times will vary by variety, so check the planting guide for your seed before beginning.
Before spring, place seeds in a plastic bag with a handful of slightly dampened clean peat, paper towels, or a mix of clean peat and sand. Seal and label the bag with your seed name and the date, then store the bag in the refrigerator (not freezer!) before planting in spring.
Once your seed has been treated, it’s ready to plant when spring arrives.
Cold Moist Stratification
In this technique, you simply add a small step to the process of creating a false winter—add moisture! The method involves dampening the seeds to soften them and allowing them to absorb water. The moisture helps spark germination.
Place seeds in a plastic bag with a handful of slightly dampened clean peat, paper towels, or a mix of clean peat and sand. You don’t want the seeds to be dripping wet! Place the bag in the refrigerator. The length of time it remains cold will vary depending on the variety of seed, so be sure to check planting guides for specific timeframes.
Frequently check the bag for mold or fungus. If any are present, plant your seeds right away.
Shop here for seeds that require cold stratification.
Varieties that need Cold Stratification