Preparing for Spring: Dormant Seeding of Wildflowers in the Fall

By Diane Wilson, Trials Supervisor, Applewood Seed Company, and Feed a Bee Steering Committee Member

Wildflowers on a FarmAs temperatures in the fall drop, many people living in cooler climates within the U.S. employ various methods to prepare for spring plantings ahead of the upcoming winter. One of the most common practices is dormant seeding of wildflowers, which is done in late fall for several reasons: (1) When supplemental irrigation is not available and adequate rainfall is anticipated in the spring; (2) when it is difficult to prepare soil in the springtime due to heavy rainfall or other factors; and (3) when wildflower seeds with high dormancy are being sown.

Seed dormancy is the inability of viable seeds to germinate under favorable conditions. An evolved trait that allows a plant species to hedge its bets, it allows some seeds to survive conditions and seasons that are unfavorable for seedling growth. For instance, some seeds may germinate right away but will perish if there is a drought that season. Dormant seeds, on the other hand, will be preserved for another season that hopefully will have more favorable growing conditions.

This practice of dormant seeding is conducted when air and soil temperatures are too low for germination, typically after several freezes but before there is snow cover. The seeds will lie “dormant” in the soil until spring when warmer temperatures and moisture are available. Soil expansion and contraction during the winter can also improve seed-soil contact required for germination.

Tractor on a FarmSeed dormancy is much more common in wildflower seeds than it is in garden flower seeds. This is because wildflower seeds are often sown in non-maintained sites with no irrigation, such as roadsides, meadows, flowers strips near croplands and wildland areas. Because these sites are often not meticulously prepared for planting, it is advantageous to sow in late fall so that seeds can take advantage of early spring moisture. Additionally, some regions experience excessive rain and moisture in springtime, making it difficult to prepare the area for planting at that time. For these areas, soil preparation, weed control and seeding can be done whenever the soil is dry enough to work in fall. Finally, the presence of dormancy in wildflower seeds makes it difficult to get immediate germination, and the winterizing effects of freezing and thawing will help to break the dormancy in the seeds.

A Field of WildflowersEven though not all the mechanisms of seed dormancy are understood, moist chilling (cold stratification) is often effective in breaking it. For perennials in particular, this requirement for a cool, moist period ensures that seed does not germinate in the early fall when seedlings would be tender and susceptible to cold or frost injury. Once the cool, moist period has ended, the seed is physiologically ready to germinate now that adequate soil temperature and moisture is available.

In order to know if your seed has dormancy, choose seed suppliers that provide clean seed that has been tested by a reputable laboratory. Complete viability reports indicate percent germination, percent hard seed and percent dormant seed. If you are planning on using seeds with high dormancy rates, then a dormant seeding in fall is often recommended. These practices work well for many of our customers here at Applewood Seed; however, be sure to check with your local seed vendors to determine the most appropriate seeding techniques for your own wildflower plantings. Remember also that many species are pollinator-attractant, and your plantings not only beautify your landscape but can also provide much-needed forage and habitat sources for local pollinators, such as bees and butterflies.

Happy planting!