Late Summer Forage Seeding for Hay and Pastures

Late summer seeding of forages is generally the most successful in PA and allows for new or renovated stands to be well established by the following spring, boosting early yields. During the season after planting, fall-seeded fields tend to produce slightly less than a maintenance field, where spring-seeded fields produce roughly 30% of a maintenance field during their first season. This is because fall seedings are well-established by spring, making them more competitive with weeds, better able to withstand dry conditions, and persist through summer heat. Spring seedings can also be successful, but wet soil conditions, increased weed competition, and the possibility of summer droughts can make it more difficult. Also, consider the demand for time to perform other spring activities, compared to activities in late summer. 

Planting Timing

For optimum forage crop establishment, plant forages at least 6 weeks before the first killing frost (below 28 degrees). This means that forage producers in Pennsylvania should seed cool-season perennials between mid-August and mid-September, depending on location and historical weather. During this time, the weather is still warm enough to encourage establishment while beating the potential extreme temperatures that settle into our state by mid-fall. September rains encourage quick establishment, and the warm days boost growth.

Typically, the ideal time to seed cool-season perennial forages across PA is:

• August 10 – August 15 for Northern PA
• August 15 – August 20 for Central PA
• August 20 – September 10 for Southern PA

Producers should pay close attention to seeding depth and seed-to-soil contact when renovating or establishing pastures or hay fields. More failures in forage establishment occur because of improper seeding depth than any other cause. Forage seeds are tiny and thus have minimal stored energy to support the seedling until it emerges and can begin making its own energy. Seeds placed too deep are not likely to emerge.

Seeding Depth

Optimum seeding depth varies with soil type (sandy, clay, or loam), soil moisture, seeding time, and seedbed firmness, but generally is not more than 3/8 inch deep. A rule of thumb is that 5-10% of the planted forage seeds should be on the soil surface after seeding. Firming the seedbed will ensure that seeds are planted at the proper depth. Accurately regulating seeding depth is difficult if the soil is soft and fluffy. Generally, an adult's footprint should not be deeper than ½ inch on properly firm soil. Forage seeds should be covered with enough soil to provide moist conditions for germination, but not so deep that the shoot cannot reach the surface.

Seed-to-Soil Contact

Proper seed-to-soil contact can be tricky when seeding into an established stand to restore or improve. Forage seeds must absorb at least their weight in water before germination begins. Unless the forage seed has been planted in saturated soils, the water generally moves into the seed from the surrounding soil. Adequate seed-to-soil contact ensures maximum water movement into the seed in the shortest time. Field situations that do not promote good seed-to-soil contact, such as cloddy or loose soil, generally result in extended germination periods and sporadic emergence. Press wheels on a grain drill or cultipacking after seeding can improve seed-to-soil contact.

If soil conditions are dry and soil moisture is limited, it would be best to delay planting. No-tilling maintains soil moisture, whereas working the ground for summer seedings can greatly reduce soil moisture. If tilling, especially in a dry year, field work and planting should be done earlier in the summer to conserve moisture.