How to Cold Stratify Seeds
Everyone wants plants. Now. But there are a small group of seeds that require a special treatment before they will even germinate in a climate that has temperatures below freezing. This process is called “Cold Stratification.” There are two ways to accomplish this.
If time is not a problem, you can put 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, they will return and bloom as expected.
If you are planting poppies direct sowing is recommended in late fall or early spring for zones 2-8
Create a "False Winter"
The second way to do this, if you want to save time, is to create a “false winter.” What this does is trick the seeds into thinking they have been in the ground for an entire year. All they need is to be in your refrigerator for at least 2 ½ months.
- About 3 months before spring, place seeds in a plastic bag with a handful of slightly dampened, clean peat, paper towel, or a mix of clean peat and sand.
- Seal and label the bag with seed name and date, then store in the refrigerator (not freezer) for at least 2½ mos. before planting in spring. (The cold period mimics a full winter’s cold.)
- Once your seed has been treated, it’s ready to plant when spring arrives.