Get Seedy This Fall
By Suzie Savoie
As summer heat moves into cooler, moister fall weather, it’s time to start thinking of sowing the native seeds acquired this year. You may have collected and cleaned native seeds from plants on your own land or purchased some native seeds that are in a box in a drawer or sitting on your desk. The next step is to plan what to do with these seeds.
Fall to early winter is the best time to sow native seeds to help restore native plant communities, increase floral biodiversity for pollinators, and reduce invasive species. Native plants are known to support a greater abundance and diversity of bees, butterflies, and other wildlife compared to nonnative plants.
More and more people in the Applegate Valley and the larger region are wanting to increase both the quantity of native species on their land for higher quality wildlife habitat, as well as for community and cultural benefits such as native plant medicine, traditional foods, basketry materials, or to simply luxuriate in a more attractive and colorful landscape. With the right species selection, native plants also require much less watering.
Although it seems counterintuitive, the seeds of many native species germinate in the fall. Seeds respond to fall rain or dew that moistens the soil and triggers fall germination. This strategy enables these species to overwinter as a small rosette of leaves, ready to bolt and flower as soon as the weather warms in the spring. These cool-season species get a jump start on growth in the fall, putting energy into underground root systems and basal leaves through the winter.
In nature, wildflowers disperse their seeds onto the ground or into the air in the summer, and as fall rains begin, some of these seeds can germinate and grow rapidly during cool, rainy fall and winter conditions. Annual wildflowers are more likely to germinate and grow in the fall, but some perennial wildflowers and native grasses will as well.
In order to help these species achieve fall germination, the seeds must be sown outside just before the first fall rain to mimic the natural cycles of seed drop and germination in the wild. The warm fall soil temperatures and rain trigger seed germination. Sowing the seeds before the first significant fall rain enables them to have enough moisture to germinate before the temperatures turn colder in early winter.
The following are examples of native species whose seeds can germinate in the fall.
Diamond clarkia (Clarkia rhomboidea)
Blue eyed mary (Collinsia grandiflora)
Bluehead gilia (Gilia capitata)
Bicolor lupine (Lupinus bicolor)
Shortspur sea blush (Plectritis congesta)
Woodland madia (Anisocarpus madioides)
Western thistle (Cirsium occidentale)
California poppy (Eschscholzia californica)
Western buttercup (Ranunculus occidentalis)
California brome (Bromus carinatus)
Tufted hairgrass (Deschampsia cespitosa)
Blue wildrye (Elymus glaucus)
Junegrass (Koeleria macrantha)
To prepare a spot for sowing native seeds, first remove existing weeds or grass without digging or tilling any deeper than a few inches. Deeper digging may unearth dormant weed seeds and encourage them to germinate, thereby increasing weed growth, which you don’t want. It is best to leave the deeply buried weed seeds undisturbed in a dormant state beneath the soil. If you have weedy rhizomatous grasses (e.g., crabgrass) or groundcovers (e.g., vinca or ivy), you will need to either solarize or tarp the area for at least one summer before seeding to clear the area of invasive plants.
For optimal results, sow seeds on a cleared area of soil, lightly rake the seeds into the soil, and then gently water. Since seeds need light and air, as well as contact with bare soil to germinate well, they won’t succeed if scattered directly over thick mulch or buried too deeply. The rule of thumb is to sow seeds as deeply as they are thick. You can cover seeds with a very light dusting of sifted potting soil, but keep in mind some seeds need light to germinate.
If there is a dry spell between rains in the fall, be sure to water! Seeds must receive regular moisture for optimal fall germination. Keep the soil consistently moist, but not waterlogged, as that can cause the seeds and/or seedlings to rot.
Other native plant seeds that don’t germinate in the fall should still be sown outside in fall to early winter to achieve the varying lengths of “cold-moist stratification” required for them to germinate in late winter to early spring.
For more information on native seed germination, including seeding into burn pile areas, check out Klamath-Siskiyou Native Seed’s Seed Germination and Propagation Reference Guide.
Happy fall seed sowing!