Chris Penrose, Extension Educator, OSU Extension, Morgan County
If and when the seed can reach the soil in late winter while there is still freezing and thawing activity, clover can fill in bare spots and add to the density of the pasture stand.
In the past, as we’ve talked about the virtues of frost seeding, we’ve suggested it’s something that is best to occur in February or March during the period when the ground is freezing and thawing almost daily. In recent years freezing and thawing temperatures haven’t always happened after mid-February. Since it’s the freezing and thawing over time that gives frost seeding a great chance to work, the time for frost seeding may be upon us soon.
Frost seeding is a very low-cost, higher-risk way to establish new forages in existing fields by spreading seed over the field and letting the freezing and thawing action of the soil allow the seed to make “seed to soil” contact allowing it to successfully germinate. When you see soils “honeycombed” in the morning from a hard frost, or heaved up from a frost, seed that was spread on that soil has a great chance to make seed to soil contact when the soil thaws. I think the two biggest reasons why frost seeding fails is people wait too late to frost seed and the seed never makes good contact with the soil. I have heard some say that they like to “overseed” or just spread seed over an established stand. Let’s face it, if the seed does not land on the soil but on existing living or dead vegetation, it does not have a chance to successfully germinate: you need exposed soil. In light of the recent snow that’s arrived and/or expected throughout Ohio, it’s important to also note that frost seeding can be done over a thin layer of snow, however, it’s important to realize that rapid snowmelt can cause the seed to be washed away from where it’s needed.
There’s still ample time to assess and seed potential fields. I am especially fond of frost-seeding endophyte-infected fescue fields where producers have issues with cattle grazing them during the summer. If you can get cattle to graze these fields in the winter, the quality and palatability are actually good, and in many cases, better than hay you may be feeding. The endophyte levels are very low now and the quality is maintained better than other forages. I actually have one predominately fescue field still stockpiled to turn cows ready to calve into in early March weeks to have a good feed and a thick sod. If you have a field you want to frost seed, if possible, abuse the field without causing environmental issues, break up the sod and expose the soil. Once that is done, go ahead and frost seed. We will rapidly run out of time for a likely successful seeding, so start as soon as possible. Typically you can start at the beginning of February through mid-March. My opinion is that once we get into March, the chance of success starts to drop depending on the weather.
The age-old question is what to plant. The seed that has the best chance to germinate and become established is red clover. For years I recommended medium red clover but I am now convinced that no matter what we plant, use improved varieties. Advancement in genetics is amazing. Numerous studies confirm that those varieties will last several years longer in most conditions. Forage trials at OSU show there several red clover varieties that have high yields and stand percentages 60% or greater after four years. These are more expensive varieties than some of the common, shorter-lived varieties, but I think it is worth it.
Red clover is a heavy round seed that has a better chance of making soil contact than a light flatter seed. Dr. Garry Lacefield, retired Extension Forage Specialist from the University of Kentucky says that clovers, seeded in the right conditions will germinate most years. Grasses are more “hit or miss” germinating about half of the time. With alfalfa, the odds are even less. Frost seeding alfalfa into an alfalfa stand rarely works as existing alfalfa is toxic to new plants. If an alfalfa field is starting to thin out, an option to extend the life of the stand would be to frost seed red clover.
Another reason to plant clover, especially red clover is the high seedling vigor. It is tolerant of a wide range of soil pH and fertility conditions and is more drought-tolerant than white clover. The advantage of frost seeding a legume like red clover is that legumes “fix” nitrogen typically in excess of their own needs, providing added fertility to other plants, improving an improved stand. Once legumes become established in a stand of grass and compose 25-30 % of the stand, there is no need to provide additional nitrogen, reducing fertility costs.
If you choose to frost seed grass, which will do best? Studies by Dan Undersander, Forage Specialist from University of Wisconsin indicate that perennial ryegrass will do best (note that it grows best in Ohio north of I-70), followed by orchardgrass, then timothy. Other studies note that annual ryegrass will work good compared to other grasses.
Some other tips to help succeed include mixing with granular fertilizer when you spread the seed. The coarse fertilizer, when mixed with clover seed will “scour” the seed coat and help in germination. Keep in mind that when you use a broadcast spreader, the fertilizer will travel twice as far as seed, so plan accordingly unless you want a striped field of clover. Over the years, I have heard people applying anywhere from 2-10 pounds of seed per acre with the lower amount applied more frequently.
Finally, grasses tend to grow earlier in the spring than legumes so where available, you could consider a light, early grazing of the grass as the clovers try to get established. You may lose some clover from the cattle trampling some new seedings, but if done right, you will set back the grass and allow the remaining clovers to establish while the grasses recover from the grazing. If you have fields with exposed soils and get the seed on early enough, I like your odds of a successful frost seeding.