The fundamental principle behind frost seeding is that alternating freezing and thawing, along with spring rains, will help to incorporate the broadcast seed into the soil surface. Seeding on top of snow is acceptable if the depth is not too great. The risk of seeding on top of snow is that a rapid meltdown may result in runoff of both water and seed. In Wisconsin, most frost seeding is accomplished during March. Be certain to inoculate legume seeds prior to seeding.
Bacterial inoculant is specific for each legume species.
For example, alfalfa inoculant is not effective on red clover. There are many excellent tools for making broadcast frost seedings. These include seeders that mount onto ATV's and tractor 3-point hitch mounted seeders. Conventional roller and grain drill seeders can also be used but will require more trips across pastures. When using spinner-type seeders, be sure to determine the effective seeding width for each seed type or mixture.