Legumes provide many benefits to grass-based pastures. However, it is often difficult to establish or maintain legumes within pastures.

The most effective way to establish forage legumes is to prepare a clean, firm seedbed and to plant with high quality equipment capable of precise, shallow seed placement.

A simpler, less efficient, but economically viable approach to establishing and maintaining legumes in pastures is "frost seeding." Frost seeding utilizes Mother Nature's alternating freezing and thawing cycles, combined with spring rains to incorporate surface-applied seed into the soil. Between now and late February is the optimum time to frost seed legumes.

Legume frost seeding works best with cool-season bunchgrass companions such as orchardgrass or bromegrass. There has been moderate success in frost seeding legumes into big bluestem, indiangrass, switchgrass and other warm-season bunchgrasses. Sod-forming grasses like tall fescue present the toughest frost seeding environment.

Common frost seeded legumes include red clover, ladino/white clover, birdsfoot trefoil and lespedeza. Alfalfa can be successfully frost seeded. However, its high seed cost and relatively poor seedling competitiveness justify the extra effort associated with intensive seedbed preparation.

I support maintaining a pasture mixture of two or more legumes. By frost seeding mixed species, you can let Mother Nature and your current pasture management "select" which species perform best across and within your pastures.

Many producers frost seed annually using relatively low seeding rates, while others frost seed every few years using higher seeding rates. Through several years of field observation, I have noticed that annually seeded fields have healthier legume populations than those that are seeded less often.

With frost seeding, we recommend applying slightly higher (total over time) seeding rates. A good rule of thumb is to annually apply slightly less than the lower end of the recommended establishment drill seeded rate. Using red clover as an example, we recommend an establishment seeding rate of 12 to 15 pounds seed per acre for broadcast and 6 to 8 pounds seed per acre for drill seedings. Therefore, the optimum annual frost seeding rate should be between 4 and 6 pounds seed per acre.

Fields that have been heavily grazed or clipped in the fall or contain low amounts of surface cover have the best chance of frost seeding success. Excessively weedy pastures present frost seeding problems through greater surface cover and increased plant competition after legume seedling emergence.

After emergence, do not over-utilize frost seeded legumes, and allow enough companion grass removal to ensure that young seedlings have access to sunlight.

Under low humidity, when application occurs within a few hours of blending, fertilizer makes a relatively safe medium by which to distribute frost seeded legumes. Fertilizer mixed with seed for greater than 24 hours or under high humidity for a few hours often reduces legume seed germination.