If you couldn’t drill clover into your pastures in the fall, you can still scatter it on them in the winter.
“Here, you can frost seed any time from December through February by broadcast seeding, whether it’s on top of the snow or just on top of the ground,” Tim Schnakenberg, University of Missouri Extension agronomist, told Ozarks Farm & Neighbor. “The freezing and thawing action in the soil will eventually work it into the soil just enough to germinate it. It doesn’t have to be deeper than 1/8 inch or so to do the job for seed that small. It’s a very simple practice; in my opinion, it’s one of the cheapest practices that we have for the benefit that we get out of it. It’s a very good way to enrich our pastures as far as adding nutrition, offsetting the effect of the endophyte problem, and basically adding free nitrogen for grasses that grow in and among the clover.”
Schnakenberg hastened to add fall seeding is still best; the legume can develop a good root system before winter, and the field is more likely to get full benefit from it the following year. With frost seeding, the clover will be a lot slower coming up in the spring, and it will probably take until the second year for the full advantage. But frost seeding is so inexpensive that it remains a good practice, and many producers do at least a bit of it every year, or every other year. “If you’re not careful, you might end up with too much clover, and too much clover can be hard on a good stand of grass,” Schnakenberg said. “We generally see people seed about a pound of white clover per acre by frost seeding, but if you’re putting in the effort of drilling it I’d recommend you up it a bit to about a pound and a half.” He also recommended inoculating the seed, particularly if it’s going into a field that hasn’t seen clover in several years.
It’s possible to lose the stand if a hard frost comes just as the small seedlings are germinated and developing in late March or April. It may also be difficult to get the clover established if there’s a lot of residue; the seed needs to be worked into the ground by the freezing and thawing cycle, and the trash on the surface can slow that down. “A lot of times, people will frost seed on top of the snow,” Schnakenberg noted. “As the snow starts to melt, the seed tends to work its way into the soil a little bit deeper than if you just put it on top of the ground. Another way is to broadcast the seed, and then turn cattle in and feed hay in the field; you end up trampling a lot of that seed into the ground.”
Rory Lewandowski, Oklahoma State University Extension Educator in Wayne County, said the best way to prepare a pasture for frost seeding is by grazing it down hard, although some light tillage or a close mowing typically done in the late fall could also be used. Because legume seeds are typically heavier than grass seed, they get down to the soil level better. Clover fixes its own nitrogen at the root zone, and the grasses are able to take on the excess nutrient, improving their quality as a feedstuff. “Once legumes become uniformly and evenly established in a stand of pasture grass and make up 30-35 percent of the stand,” he said, “there is no need to apply supplemental nitrogen, so this portion of fertilizer cost is reduced.”
Lewandowski said red clover is probably the most widely used forage species when it comes to frost seeding; it has high seedling vigor, is tolerant of a range of soil pH and fertility conditions, and tolerates drought better than white clover. However, most varieties will typically persist in a stand for only a couple of years, although there are now some varieties available that can last 3 or more years. “Some producers like a combination of red clover and birdsfoot trefoil in their frost seeding mix,” he noted. “Birdsfoot trefoil is a persistent perennial once established, but it can be slow to establish, often not showing up in a stand until the second year after frost seeding.”
