To be frank, frost seeding is not a silver bullet, full-proof method of sowing seed, particularly when compared to using a drill. For me, however, it has proven to have a high enough rate of success that I regularly incorporate the practice within my overall food plot management plan.
Frost seeding, aka winter seeding, is a quick and economical way to sow cover crops or traditional plantings. Mid-March is generally the perfect time to frost seed, as most northern areas still have about an inch of snow on the ground. Should you have a standing crop of winter rye, wheat, or barley, you can frost seed it to supplement a thinning plot of grain.
Now is when the soil is going through its annual heave-and-hoe (freeze-thaw) cycles. The ground movement creates tiny holes in the surface of the soil that creates excellent seed-to-soil contact. When selecting a plot site to frost seed remember that this method works best on loamy and clay soils that hold water. Avoid frost seeding on sandy or “shaley” soils as they dry out quickly.
The best time to perform frost seeding is while the soil is frozen. In March, that usually means frost seeding a plot in early in the morning after the overnight temperatures have helped to keep the soil frozen. It is especially successful when a plot is seeded while the early morning soil is hard, but the temperatures are expected to be high enough to create a thaw later in the day.
The best varieties are the small seeds that both germinate quickly and grow well in cool conditions. For example, use winter hardy varieties of red and white clovers like Alice White Clover or Red Marathon Clover or, better yet, Frosty Berseem Clover (it can tolerate -14° F) or FIXatioN Balansa Clover (can tolerate 0 to 5° F) and Birdsfoot trefoil. Frost seeding is the best method of planting perennial clover food plots. These are ideal clover choices to frost seed. When using other legumes or grasses like Timothy, expect less success than when clovers are frost seeded. Should you frost seed other varieties of legumes, be sure they are pre-inoculated. Otherwise you will have to inoculate them with the appropriate live bacteria rhizobium that will help the plant to fix nitrogen.
Make sure to check the seeding rates per acre of each seed prior sowing the plot. Using the correct weight of seeds is important to avoid over seeding a plot. Frost seeding helps in seeding a uniform planting as it is easier to see the seed lying on top of the snow. Speaking of which, while it is best to frost seed over frozen bare ground, it can be done over snow if the snow is ½- to 1-inch deep. I have had my optimum frost seeding success, though, when broadcasting seed in early spring after the snow is gone but the ground is still frozen.
The magic about frost seeding clovers is that even if the ground conditions are not perfect for frost-seeding, clover seeds will remain viable in the soil. When the conditions are right, they tend to grow anyway. In the Spring, should you notice your stand is under-seeded (thinly planted) do not panic. You can top-seed clovers and other no-till type legumes or grasses to fill in the plot.