Frost seeding involves strategically broadcasting or overseeding legumes, such as red clover, into a tired pasture or within a small grain stand. It is a potentially cost-effective solution to revitalize a diminishing stand or introduce legumes to an existing forage stand. Frost seeding is usually not recommended with grass species. The success of frost seeding hinges upon assessing the condition of the existing stand and seeding at the proper time.
Timing:
Timing and soil conditions are critical to the success of frost seeding. Typically, frost seeding falls between mid-February and early March, coinciding with the freeze-thaw cycle. The rhythmic expansion and contraction of soil during freezing and thawing create a honeycombing effect, facilitating seed incorporation into the soil profile and ensuring good seed-to-soil contact. If there is snow on the ground, it is not recommended to frost seed the goal is to get the seed on bare soil. If it snows after frost seeding, that is fine. Consequently, it is important to check weather forecasts and watch the highs and lows to help aim for hitting that freeze-thaw interaction.
Condition of the stand:
A thick thatch can pose a challenge, hindering optimal seed-to-soil contact and fostering competition for the seedlings. To mitigate this, it is recommended to closely hay or over-graze in the fall or winter prior to frost seeding to open the canopy. Ideally, visibly bare spots are a good indicator of a forage stand that frost-seeding is more likely to be successful.
Other considerations:
Soil type can also influence the potential success of frost seeding. Sandy soils do not expand and contract as much during freeze–thaw cycles, limiting the natural heaving action needed to incorporate seed into the soil. Additionally, sandy soils can dry out quickly. Very dry soils behave similarly. Because of this, frost seeding tends to be more successful on loam or clay soils with sufficient moisture.
Don’t forget to pay attention to conditions to avoid causing soil compaction with frost seeding. Often this may require frosting seeding in the early morning while the soil remains frozen, especially if conditions are wet. Under some conditions, the use of animals can help incorporate the seed, ensuring good seed-to-soil contact through their hoof action, but doing this when the field is too wet can lead to the pugging up of the pasture.
The fate of frost seeded stands hinges significantly on spring moisture levels. Adequate moisture is vital for establishing a healthy stand. Thus, while the potential benefits of frost seeding are high, timing, soil condition, and moisture play important roles in success.
A few well-researched steps will improve the success of frost seeding. For additional information on frosting seeding, check out the ISU Extension and Outreach publication Improving Pasture by Frost Seeding.
- Assistant Professor
- Forage Extension Specialist