Tips for Overseeding Central Kentucky Horse Pastures

Fall is the optimal time for horse pasture improvement in Kentucky, according to researchers at the University of Kentucky (UK). And within that window of time, mid-August through mid-September is considered the sweet spot for pasture establishment. This is the time of year when weed competition is low and ideal growing conditions exist for cool-season grasses.

One of the best pasture management practices available to horse owners is overseeding, or planting seed in a field with existing grass cover to fill in bare patches and thicken the stand. Overseeding helps ensure good ground cover, quality grazing, and an aesthetically pleasing pasture in the coming year without major pasture renovations. This can be done over the entire pasture or it can be limited to trouble areas.

Ray Smith, PhD, forage extension specialist in the UK College of Agriculture's plant and soil sciences department, offers the following recommendations to increase the chances of a successful overseeding:

Common Seeding Rates and Optimum Seeding Dates for Horse Pastures
Species Rate lb/A (seeded alone) Rate lb/A (in mixtures) Optimum Seeding Dates
Endophyte-free tall fescue 20 - 40 10 - 20 8/15 - 9/15
Orchardgrass 15 - 30 10 - 15 8/15 - 9/15
Kentucky Bluegrass 15 - 30 10 - 15 8/15 - 9/15
Endophyte-free Perennial Ryegrass 20 - 40 5 - 10 8/15 - 9/15
  1. Apply any needed lime and fertilizer amendments. An up-to-date soil test will indicate nutrients needed for both established and growing plants. For more information, contact your local county extension agent or consult Soil Sampling and Nutrient Management in Horse Pastures.
  2. Use high-quality seed of an improved variety. Use a variety that has proven to be a top performer under Kentucky conditions. The University of Kentucky forage testing program tests the survival of cool-season grasses under grazing by horses and reports these findings in Forage Variety Trials. High-quality seed has high rates of germination and is free of contamination from weed seed. Remember, Smith said, quality seed will produce a pasture that lasts for years; "cheap seed" will only lead to headaches.
  3. Plant enough seed. Seeding rates are determined by the grass mixture to be planted. See Table 1 for the recommended seeding rates in pounds per acre as well as the optimal time to plant common forage plants.
  4. Use the best seeding method available. Smith recommends no-till drill seeding for overseeding existing pastures. The goal of any method is to place the seed ¼ to ½ inch into the soil and cover it to achieve good seed to soil contact. Run the seeder in two directions across the field to ensure better coverage.
  5. Control competition. Close mowing or grazing prior to overseeding in the late summer and fall will reduce weed competition.
  6. Use recommended waiting periods when applying herbicides. In addition to limiting grazing of an overseeded pasture, also limit herbicide applications at critical times. Typically, seed at least six weeks after spraying and then wait until the grass seedlings are at least 4 to 5 inches tall before spraying again. Always follow herbicide label directions because some of the newer herbicides have even longer waiting periods. For more information, see Weed Management in Grass Pastures, Hayfields, and Other Farmstead Sites.
  7. Allow time for seedlings to establish. Returning horses to an overseeded pasture too soon can wipe out any seedlings by grazing or trampling. Ideally, a pasture should have one year of rest after overseeding before heavy grazing resumes; however, seedlings can generally tolerate a few sessions of light grazing. Harvesting the pasture once for hay after the grass has reached maturity before returning the pasture to full grazing is also recommended. If it is not possible to limit grazing for a full year, consider using temporary fencing and overseeding half of a pasture one year, then the other half the following year.

Other considerations when overseeding:

  • Do not plant endophyte-infected tall fescue in pastures grazed by pregnant mares. Make sure you are instead planting endophyte-free tall fescue in broodmare pastures.
  • Perennial ryegrass is a short-lived, cool-season grass that has exceptionally high seedling vigor and is often used to thicken troublesome areas. If perennial ryegrass is seeded at high rates (less than 25%), it will outcompete other grasses, which will result in bare spots as perennial ryegrass dies out in two to three years. Perennial ryegrass can be infected with an endophyte similar to that of tall fescue; therefore, only endophyte-free perennial ryegrass should be seeded in broodmare pastures.
  • Purchase seed well in advance of overseeding. High quality seed is in great demand in the fall, and supplies run out quickly.
  • Store seed in a cool, dry area to maintain germination levels. Refrigerators are excellent storage sites if room is available. Always store in rodent-proof containers.

For more information on establishing horse pasture:

Ray Smith, PhD, is a forage extension specialist at the University of Kentucky.

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