Richard Taylor, Extension Agronomist; rtaylor@udel.edu
If you haven’t been able to finish planting pasture and hay fields with a cool-season grass (CSG) or CSG pasture mix by now, your best shot at having a successful seeding will be to wait until late summer or early fall to plant the new field. As a temporary measure, you can choose one of the annual warm-season grasses (WSG) such as sudangrass, a sorghum-sudangrass hybrid, teff, pearl millet or pearl millet hybrid, or even one of the new forage crabgrasses to plant in the field and produce feed for grazing or hay until you are ready to plant late this summer. Crops like sudangrass or the sorghum-sudangrass hybrids are very good smother crops and will help coke out weeds and result in a cleaner seedbed later this year.
Other suggestions to consider for new spring forage plantings include waiting until you have 2 to 4 inches of top growth on the forage grass seedlings and then topdressing with about 20 to 30 pounds of nitrogen per acre. Application of nitrogen at this point will stimulate grass growth and will tend to benefit the grass that, by this time, has established a fibrous root system capable of taking up nitrogen more efficiently than the tap-rooted broadleaf weeds. Stimulating early growth of the grass seedlings will help them compete against weeds and will help establish a larger root system while soils are still cool so the grass has a better chance of surviving periods of dry weather and heat as summer begins.
If you find that the new seeding has a lot of weeds that are ahead of the grass seedlings, try clipping or mowing the area to be sure that enough sunlight reaches the grass. You may need to continue this activity for several months and especially later in the year when the weeds begin to flower and mature seed. Mowing will at least reduce the amount of weed seeds returned to the soil weed seed bank.
Finally if the new seeding is for grazing, do not start grazing too early. If you have the land resource available, use the new seeding for at least one hay crop before changing it back to support grazing animals. This helps the grass become better established with larger root systems so that the animals do not pull new plants out of the soil. Also, keep the grazing pressure light during the first year, allowing the pasture regrowth to get 10 to 12 inches tall before beginning grazing and remove animals before they graze the pasture closer than 4 to 6 inches. The use of temporary fencing to do intensive rotational grazing is very helpful in managing new pastures and ensuring a vigorous healthy stand.