Planting grasses and legumes in late fall or winter can work nearly as well as in early spring, says Bruce Anderson, University of Nebraska Extension forage specialist.
“Dormant plantings succeed as long as your soil is relatively dry and soil temperature is too cold for seeds to germinate,” he says. “That's the main key – too cold to germinate. When these conditions exist, seed just lies in the soil until conditions favorable for germination occur next spring. Then seeds begin to grow as if they had just been planted.”
Warm-season grasses, like those used in CRP and range plantings, are especially well-suited to dormant planting. They won't germinate until the soil temperature exceeds 45°. Since soils generally remain colder than that for most of the winter, dormant plantings of these grasses can be made anytime between late November and March. In addition, the alternate warming and cooling of the soil in spring stimulates a natural process in these seeds that improves their germination.
Cool-season grasses and legumes, however, can germinate at soil temperatures as low as 35°. Nebraska soils often are warmer than that for several days in a row during winter, so cool-season grass seeds occasionally germinate and then die when soils freeze again. As a result, dormant plantings of cool-season species are successful a little less often than those of warm-season grasses.
“If you want to plant grass but never seem to have enough time or the right soil conditions to do a good job in spring, try dormant planting,” Anderson suggests.