When it comes to planting native seed, most people in Illinois and the Midwest think of spring and summer. This is when the seed of annual vegetables and flowers and grass is planted in gardens, landscape beds and lawns.
Native plant seed, however, can be, and in most cases should be, planted in late fall through late winter, a technique called “frost seeding.” Planting at this time of year is typically the best of the year to plant native seed as it mimics and takes advantage of a natural process. If you missed this fall/winter window and you are seeding in spring, this is fine, but usually not quite as good. Read below about frost seeding and its benefits.
Frost Seeding Explained
Every season, native wildflowers, grasses, and sedges, and shrubs and trees develop and drop their seed. This seed rests on the surface of the ground. In winter the ground freezes. At some point, it thaws a bit, then freezes again. This cycle repeats naturally again and again. During this cycle, native seeds on top of the ground slowly work their way slightly into the soil. When spring temperatures arrive and moisture once frozen in the soil melts into water, the seeds are naturally “planted” and watered into the soil. These seeds germinate and grow hardy root systems while there is plenty of moisture in the soil. Because of this, these plants typically don’t need additional watering during the summer.
Most native plants of the Midwest need this freeze-thaw cycle, which is called “cold-moist stratification,” to germinate. This is true of most wetland, woodland, and prairie seed, sunny or shady native seed.
Native Plant Species To Frost Seed
How do you know if a certain native plant species should be frost seeded? Most native grasses do not, but just about every other species of native flower, native sedge, and native rush does require cold moist stratification. If you want to learn more about native seed stratification click here.
How to Frost Seed
Frost seeding is easy. Instead of waiting until after the threat of frost has past to plant sensitive annual seeds, frosty conditions are preferred! Native seed can be planted anytime between December and March, when soil temperatures dip below 40° F. Most native species need 30-90 days minimum of cold-moist stratification so the earlier you get it on the ground between those dates the better. Some folks will broadcast seed when snow is forecasted. This is because snow can cover the newly planted seed, protecting this precious resource from blowing away or being eaten by birds. If your ground is fairly level and erosion is not a major threat, there’s no need to cover the seed. Simply evenly broadcast seed over the soil, and let the freeze-thaw cycle of winter do the rest. While not necessary, it can help to remove dead vegetation and thatch from the area before seeding to get better “seed to soil contact”. This ensures the seed will be in contact with the soil from the start. If you do have a slope, you are in an area with concentrated flow, any chance of erosion, or for security sake you may want to consider erosion control blanket and/or erosion control cover crops. Spring may be your best bet for certain native seed applications in high erosion potential areas. Erosion can be tricky, talk to us if you need erosion control suggestions.
Achieving desired results from native seeding can be a bit tricky and confusing when compared to most other types of gardening and landscaping, but only if you do not have the correct instructions. To learn more about native seed preparation, installation and maintenance please feel free to look at these resources for the basics or lean on us for help with more advanced cases. We provide paid onsite native restoration consulting and free phone advice as well. To learn more about other ecosystem restoration consideration and ecosystem best management practices click here.
Chief Ecological Officer
Natural Communities, LLC.