Seeds of many native plants have built-in protections that keep them from germinating at the wrong time, such as before a frost, in the fall, or during droughts. In the wild, seeds will lie dormant in the soil until the right conditions are present to insure success. There are a variety of methods that seeds use to break that dormancy, and many plant species have specific needs. To successfully grow a plant from seed, we often need to learn how specific seeds naturally break their dormancy. We can use these methods, called stratification, to increase the chances of seed germination.
Methods for breaking dormancy are quite varied and rely on one or more factors including air temperature, time, moisture, light vs. no light, and soil temperature. The most common methods involve a combination of moisture, air temperature and time. It can be as simple as two months in cold, dry storage and as complex as a lengthy sequence of alternating cold, moist periods, with warm, moist periods. (This method generally means a seed will require over a year to germinate).
There are general how-to guidelines derived from the experience of growers and hobbyists that will improve your success. Catalogs from native plant nurseries are a great source of information for particular plant species. Also, this website Native Plants for Tennessee operated by the University of Tennessee’s Smart Yards Program includes a description of 12 different methods for breaking dormancy in our Definitions section under Germination Codes. This germination code information was provided courtesy of Prairie Moon Nursery, a native plant source in Winona, Minnesota. In addition, each plant in our Native Plants for Tennessee database has a description of which method or methods work best. Plant specific data on this website is taken from a host of native plant resources including the Prairie Moon Nursery catalog.
The two most common methods are: (1) cold, dry storage, and (2) cold, wet storage. These methods are commonly called cold, dry stratification and cold, wet stratification.
Cold, dry stratification typically means you do not need to provide any pre-treatment. The native plant nursery will have stored the seed under these conditions prior to its sale. You can plant the seed as soon as your planting schedule requires it. Prior to planting, simply store the seed in a cool, dry place or under refrigeration at 33-40 degrees F.
Cold, wet stratification means seeds germinate after an approximate number of cold days and moist storage (typically around 60 days). Prairie Moon Nursery’s catalog describes two different methods of cold, wet stratification for the home gardener; this information is also available on their website at
The first method is storing seed in dampened sand as follows:
(1) Add 1 -2 teaspoons of water to 1/3 cup fine sand for each 1/8 oz of seed to be treated.
(2) Mix the seed, sand and water and refrigerate in a sealed plastic bag for the required time period.
The second method is using a dampened paper towel or coffee filter as follows:
(1) Rinse a coffee filter or paper towel in water and squeeze out excess water.
(2) Place seed in a single layer on the damp paper, fold over the paper and place it in a sealed plastic bag.
(3) Add a dry paper towel inside the bag to help maintain even moisture by pulling excessive moisture away.
(4) Store in the bag in the refrigerator for the required time period.
For more detail, see Prairie Moon’s step-by-step tutorials at https://www.prairiemoon.com/PDF/PrairieMoon.StartingFromSeedSheetWEB.pdf
From a very practical standpoint, the easiest way to do cold, wet stratification is to let nature do it for you. Simply plant the seed outside in its designated spot in late fall or early winter and allow the seed to go through nature’s stratification process. This eliminates the need to monitor your refrigerated seed for premature sprouting, mold, or drying out. However, you will need to increase the amount of seed that you plant to allow for seed loss during the winter because seeds are susceptible to hungry birds or rodents, can be blown away by wind, and washed away by rain.
Always remember, each plant has its own set of adaptations for germination. Be sure to check the specific germination requirements for the specific plant species you want to grow. It is a little more work, but it can make the difference between success and failure.