Pastures that thin out over time can sometimes be brought back to productivity by overseeding. Overseeding is simply the practice of broadcasting legume or grass seed with the intent of thickening the pasture and prolonging its productive existence. When the pasture overseeding is conducted in February and early March, it is sometimes referred to as “frost seeding.” Freezing and thawing of the soil surface at this time of year helps seed come into contact with soil. In most cases, legumes are overseeded into grass pastures, but grasses may sometimes be successfully overseeded into grass pastures as well.
The Year Ahead of Pasture Overseeding…
- Correct soil fertility and pH deficiencies.
- Control weeds.
- Clip or graze the pasture to reduce height and thickness of grass.
- Manage populations of voles, gophers, other “varmints.”
Consider the Site…
- Pasture, that is being overseeded, should not have a steep slope. (Steep slope causes new seed to wash downhill with rain.)
- The pasture should have exposed areas of soil, without excessive weed growth or thatch.
- The pasture grass should not be excessively tall. The grass should have been grazed or mowed.
- “Bunch-type” grasses compete less with new legume seed.
- When overseeding legumes, hold off on nitrogen applications while legumes are becoming established.
Consider the Date…
- February overseeding (not on snow) will promote seed-to-soil contact during freeze-thaw cycles.
- Mid-to-late March seedings may benefit from use of spring-tooth drag harrow to improve seed-to-soil contact.
- Later overseeding may not be advised because of higher soil surface temperatures and reduced chances of regular light rain.
Preferred Species for Overseeding…
- Red clover (4-10 lbs.), alsike clover (1-4 lbs.) and ladino clover (1-3 lbs.) establish rapidly in grass pastures.
- Birdsfoot trefoil (5-8 lbs.) has low risk of bloating, but is slower and more difficult to establish. Trefoil has a longer life than many of the clovers.
- Kura clover may be used as well but can be difficult to establish, has poor seedling vigor.
- Korean lespedeza (8-15 lbs.) may tolerate poor sites better than other species.
- Alfalfa (6-10 lbs.) may be overseeded if pH is adjusted high enough and drainage is adequate. Alfalfa does not compete well with dense grass or on poor sites.
- Grasses that may be overseeded into grass pastures include timothy, orchardgrass, and tall fescue. The success with grass overseeded into established grass pasture is somewhat inconsistent.
Maintaining Overseeded Pastures…
- Periodic grazing after legumes become established is beneficial, but avoid excessive grazing and trampling.
- Control weeds as new seedlings become established. Consider mowing or clipping if grazing cannot be managed.
- Maintain soil fertility and manage grazing to keep pasture thick and productive. Remember that nitrogen application favors the grasses over the legumes