Frost seeding is one method that producers can use to renovate pastures and improve pasture quality and/or the species mix within the pasture. Frost seeding involves broadcasting seed over a pasture area and letting the natural freeze/thaw cycles of late winter and early spring help to move the seed into good contact with the soil. A basic requirement for frost seeding success is to make sure that the sod cover has been opened up, that is, that there is not so much growth present that the broadcast seed will not be able to come into contact with bare soil. Generally, a pasture is prepared for frost seeding by grazing it down hard, although some light tillage or a close mowing could also be used.
Another twist to frost seeding that cattlemen can use to their advantage is to combine frost seeding with hoof action. Under this seeding scenario, let your cattle begin to graze the paddock that is to be frost seeded in early March. Let the cattle graze down the forage, scuff up the soil and open up bare areas in the sod. At this point, broadcast the forage seed across the paddock. Keep the cattle in the paddock another couple of days and let them continue to graze and trample or hoof in the seed. As a precaution realize that in certain soil conditions this method may not work as well with cattle as it does with sheep because if allowed to graze too long cattle could trample in the seed too deep.
In general, legumes work better for frost seeding as compared to grasses. This might be because legume seeds are typically heavier than grass seed and that may help them get down to the soil level better than grass seed. The advantage to frost seeding a legume such as red or white clover is that legumes "fix" nitrogen typically in excess of their own needs. The existing grass plants use the excess nitrogen, which improves their quality as a feedstuff. Once legumes become established in a stand of pasture grass and compose 25 to 30 % of the stand, there is no need to apply supplemental nitrogen so this portion of fertilizer costs is reduced.
Red clover is probably the most widely used forage species when it comes to frost seeding. Red clover has high seedling vigor, is tolerant of a range of soil pH and fertility conditions, and tolerates drought better than white clover. Red clover produces its heaviest growth during the summer months. Red clover is known as a short-lived perennial, typically persisting in a stand for only a couple of years. Thus, many producers find themselves frost-seeding red clover every couple of years back into the same pasture. However, work is underway to improve red clover longevity and there are a couple of varieties on the market that in OSU trials have high yields and stand percentages of around 60% or greater after 4 years. This seed is higher in cost than some of the more common shorter-lived red clovers, but may be worth it to some producers in some pasture situations.