By Marvin Hall
Farmers are frequently faced with the situation of planting perennial cool-season forage crops later in the fall than is recommended. The risks of late planting must be weighed against considerations such as need for forage the following year or ground cover to comply with conservation plans.
Research done at Penn State found that planting forage legumes after Aug. 1 reduced percent ground cover and yield during the year after planting. Total DM yields for the year after planting were reduced by an average of 158, 105, and 76 lb/acre/day for alfalfa, red clover, and birdsfoot trefoil, respectively, when planting was delayed after Aug. 1. Generally, planting legumes after Sept. 5 in central Pennsylvania and Oct. 1 in southern Pennsylvania resulted in total yields of less than one ton/acre during the year after planting.
Delays in planting had less effect on grass than legumes, but grass species responded differently. Orchardgrass and perennial ryegrass yields did not decrease until planting was delayed until after Sept. 5 when average yield the year after planting declined by 100 and 153 lb/acre/day, respectively. Planting reed canarygrass after Sept. 5 resulted in total DM yields of less than one ton/acre during the year after planting.
Recommendations. Planting early is best but if that is not possible then planting perennial cool-season forage crops, in fertile well-drained soils, after Sept. 5 in central and Oct. 1 in southern regions of Pennsylvania severely jeopardizes the vigor of the seedlings and generally results in yields that are too low for practical forage harvesting.
Source:psu.edu