- Frost seeding can be an effective, low-cost method to introduce new forage species into an existing sod or to maintain the species makeup of pastures.
- Providing good seed-soil contact and limiting plant competition is key to frost seeding success.
- Frost seeding is most successful with legume species like red clover.
- Seeding in March is preferred for the upper Midwest.
Benefits of frost seeding
The goal of frost seeding is to let freezing and thawing, along with spring rains, help seeds enter the soil surface. Frost seeding of legumes and grasses can help improve pasture yields or change forage species makeup within the pasture without complete renovation. The pros of frost seeding include:
- Being able to establish forage without disturbing the sod
- Requires less labor than traditional seeding methods
- Doesn’t require a large investment in equipment
- Shortens “non-grazing” periods
While frost seeding can be beneficial, less seeds will establish and become productive plants compared to traditional methods.
Tips for successful frost seeding
- Seed to soil contact is key to establishing forage through frost seeding. To make sure your seed-soil contact is good, closely graze pastures in the fall or winter to open forage stands and expose the soil.
- Avoid sod-type grasses like bluegrass when there’s a thick layer of old grass covering the soil surface.
- Reduce plant competition for new seedlings by:
- Grazing pastures down to two inches in the fall will help to slow regrowth in the spring.
- Graze frost-seeded pastures often in the spring and summer to allow for light to reach the new seedlings, but don’t graze new seedlings until the plants have had time to establish good root systems.
- When frost seeding both grasses and legumes, seed grasses separate from legumes (make two passes) when using a broadcast seeder due to differences in seed density.
Timing of frost seeding
- Most frost seeding occurs during March in the upper Midwest.
- You can seed on top of snow if the snow depth isn’t too great.
- Runoff of both water and seed due to rapid snow melt is a risk of seeding over snow.
Many excellent tools are available for broadcast frost seedings. They include:
- Seeders that mount onto ATVs
- Tractor three-point hitch mounted seeders
If using a spinner-type seeder, be sure to determine the effective seeding width for each seed type or mix. This will vary between species.
Introducing legumes into grass stands
Often, horse owners use frost seedings to introduce or increase forage legume species into a grass stand. Legumes increase energy and protein content in pastures but will limit chemical weed control options.
- Frost seedings have been successful with red clover and birdsfoot trefoil. Red clover establishes quickly and remains productive for the first two years.
- Frost seedings of alfalfa, alsike clover and white or ladino clover have varied in success.
- Don’t frost seed alfalfa in cases where alfalfa plants already exist in the stand. Established alfalfa naturally releases chemicals that prevent new seedlings from establishing.
Introducing a legume into a grass pasture limits chemical weed control options. Only introduce a legume if the pasture is mostly weed-free and the horses need more energy and protein.
Be aware of mold-infected clover
Clovers infected with mold can lead to photosensitivity (thickening and reddening of white skin), liver damage and slobbers. When not infected with mold, clover is a good source of high quality nutrients. See Feeding clover to your horse for more information.
Introducing grasses into legume stands
It’s hard to establish cool-season grasses, such as timothy and orchardgrass in stands of legumes through frost seeding.
- Perennial ryegrass and orchardgrass are the most successful.
- Smooth bromegrass is moderately successful.
- Reed canarygrass and timothy are the least successful.
Although smooth bromegrass is only moderately successful, its sod-forming growth habit would likely result in more plant growth. Smooth bromegrass and reed canarygrass often need a full growing season before the plants are productive.
Ryegrasses don’t overwinter well in the Midwest. Therefore, you should only seed them with the intent of providing forage for a single season. Ryegrasses and orchardgrass increase forage yield during the seeding year.
The rate that you frost seed at depends on the sod’s condition, the species you seed and the number of seedlings you want in the final stand. To best determine seeding rates, you may need to carry out trial and error over a few years. See the table below for a rule of thumb when seeding into forage stands.
Recommended seeding rates for frost seeding into existing grass or legume sod
|Species||Rate (lb/acre) - seeded alone||Rate (lb/acre) - As part of seed mix||Expected established plant* (plants/sq. ft.)|
|Birdsfoot trefoil||4-6||2-3||6-9 (second year)|
*Expected plants based on “alone” seeding rates
**Use higher rate in “bareground” cases and lower rate in existing sods
Reviewed in 2020