Seeding rate and seeding date are mutually influential. For example, a later seeding date with a grass crop might mean less tillering in the fall, demanding a higher seeding rate to achieve the same ground cover.
Planting dates that stretch later into the fall produce far less cover crop biomass, heights, and ground cover. The month’s difference between mid-September and mid to late October can reduce biomass by 50%. Earlier planting means faster seed germination and growth, and allows the crop to become better established prior to fall dormancy. This provides maximum groundcover. An earlier planting also helps buffer against adverse fall weather. Delaying planting by a day in the fall really shows up negatively in the spring harvest.
Seeding rate is sometimes, but not consistently, a predictor of yield and establishment. Small grains often make up for low seeding rates with more abundant tillers –more cost-effective for you. When seeding a cover crop in the fall, grabbing an early planting window is probably more critical than a higher seeding rate, but you may have no choice and be forced to make up for late planting with a higher rate.
We’ve also found that with some small grains like wheat and barley, increasing the seeding rate from 100 lbs to 130 lbs. doesn’t make a whole lot of difference to final tonnage (if planted in a timely manner), but adding another species, like crimson clover at 20-25 lbs., can significantly improve yield.