Cold Moist Stratification

Many wildflower and grass seeds have a dormancy built into them, which prevents germination. In nature, this dormancy protects seeds from germinating as soon as they fall on the ground and forces them to wait for the ideal growing conditions of spring. For example, if they were to germinate in September, the seedlings would not be big enough to make it through the winter.
To know if a species requires cold-moist stratification, find the species on our website and click “Additional Information”. If the planting season says “Dormant”, then this guide is for you!

There are two ways to achieve cold moist stratification:

Method 1: The best method for breaking dormancy is to plant the seed during the dormant season (in southern MO, this is Nov. 15 – Feb. 15) between December and February.  A benefit of dormant winter planting is that freezing and thawing and rain can work the seeds into the soil, helping to establish seed-to-soil contact. When the seed is in contact with the soil it can imbibe water, go through cold-moist stratification, then germinate when the temperature is warm enough in the spring.

Method 2: The following process will help to break dormancy in seeds when planting later in spring is the only option.

1. Place seeds in a plastic bag & label the outside with the date and species name.  Use a nylon weave bag for larger quantities; leave room for swelling.
2. Cover with water. Let soak for 4 hours.
3. Poke pin holes in the bottom of the plastic bag to drain excess water (you do not need to poke holes in the nylon weave bag). Allow the bag to sit or hang to drain out excessive water. Be careful not to lose small seeds, but there should be no visible water in the bottom of the bag.
4. (Optional) Mix the seed with an equal amount of perlite or fine, sterile builder’s sand in a plastic bag to increase air flow.
5. Store in the refrigerator 4 to 5 weeks.
6. Check weekly for germination or molding; if either occurs, plant as soon as possible. Also, check the moisture; if dry, add a small amount of water.
7. Plant the seed after the elapsed time and the threat of below-freezing temperatures has passed. Make sure you are able to get good seed-to-soil contact. Here you can find a guide: https://hamiltonnativeoutpost.com/preparing-your-seed-bed/
8. If possible, after planting, water the area twice a week for two weeks, then once a week for a month if no rain falls.  For the remainder of the growing season, water when it is unseasonably dry. Note: you only need to water the seeds when you are planting outside of the recommended planting window, meaning the soil moisture is not as good.

Method 2 is not foolproof.  Method 1, Mother Nature’s way of breaking dormancy, is more reliable than anything we can do.

Hybrid method: If you have barely missed the dormant planting timeframe, it is also an option to do a hybrid approach. Do steps 1,2, and 3. Store seeds in refrigerator and try to plant within a couple of weeks, ideally before a rain or a watering.