There's something deeply satisfying about growing plants from seeds. More than cuttings or divisions, seeds hold the promise, or at least the potential, for new life.
Most seeds packaged for sale in retail stores are easy to germinate. They might take a week or more to emerge, but they don't require special treatment other than adequate warmth, moisture, oxygen and sometimes light.
Seeds purchased from native plant nurseries or collected from wild native plants often need more attention. Many of these seeds are dormant, meaning they won't germinate even in favorable conditions. It's an adaptation that prevents the seeds from germinating when the seedlings are unlikely to survive, such as in late fall heading into winter.
Causes and Treatments
Seed dormancy has many causes, and different species have different causes. For example, the seeds of ironweed, Vernonia fasciculata, need cold, moist conditions for a month or two before they'll germinate. That's likely due to immature embryos that need time to develop and/or chemical inhbitors that must leach out or otherwise diminish in concentration before the embryos can grow (1).
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| Ironweed flowers in late summer and early fall with brilliant purple heads of flowers. These plants were about 6 feet tall. Eventually the heads fill with bundles of seeds that are wind-dispersed. |
Nature provides those conditions over winter, but the seeds can also be treated artificially. In a process called cold-moist stratification, the seeds are placed in a damp medium or on damp filter paper and refrigerated for some length of time. How long the seeds must be stratified depends on the species. For ironweed, it's one or two months.
Another example is smooth wild rose, Rosa blanda. The small, seed-like fruits, called achenes (ah-KEENs) of this native shrub are doubly dormant, meaning they have two types of dormancy that must be overcome before the seeds will germinate. In this case, the embryos are immature even when the hips are red and ripe, In addition, the seeds are surrounded by a hard pericarp, or fruit wall, that physically prevents germination (2).
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| Smooth rose blooms in late spring and early summer. Rose hips ripen in early fall, Each hip contains several small, seed-like fruits called achenes.Each achene has a hard fruit wall, or pericarp. |
In nature, the double dormancy of the achenes is broken by up to two years of cold (winter) and warm (summer) conditions. The seeds then germinate the second spring after they are produced.
Artificial treatment of the achenes begins with scarification, a wearing away of the pericarp by immersing the achenes in boilng water, rubbing them lightly with sandpaper, or using other methods. Then the seeds are stratified in alternating temperatures, starting with cold-moist stratification, then warm-moist stratification (60-70 F), then another cold-moist stratification (3, 4). The Propagation Protocol Database (5) recommends one month of warm-moist stratification followed by four months of cold-moist stratification.
Seed dormancy is a complex topic involving biochemistry, ecology and evolution. To learn more about it and to learn how to break the seed dormancy of particular species, see the reference sections after Cited References.
Cited References
1. Germination of Native Prairie Forb Seeds. J.T. Sorensen and D.J. Holden. Journal of Range Management Volume 27, No. 2. 1974.
2. Seed Germination within Genus Rosa: The Complexity of the Process and Influencing Factors. Roxana L. Stoian-Dod and others. Horticulturae Vol. 9, No. 8. 2023.
3. Smooth Rose (Early Wild Rose, Meadow Wild Rose, Labrador Rose). G.D. Bebeau. The Friends of the Wildflower Garden, Inc. Trees & Shrubs of the Eloise Butler Wildflower Garden. 2013.
4. Rosa blanda, Early Wild Rose. Prairie Moon Nursery. Website accessed December 24, 2025.
