Frost Seeding Time Is Here

Mar 09, 2022

By David Hartman and Zachary Larson et.al

Frost seeding is an economical way to establish cover crops in the winter in standing wheat or barley or to supplement a thin forage stand. Though not as fool-proof as drilling, it is a reasonably successful practice.

Now is the time to perform this practice as the soil is going through freeze-thaw cycles. This causes a 'honey-combing' of the soil surface which helps to improve seed-to-soil contact. Frost seeding works well on loamy and clay soils that hold water but is not suited for use on sandy or shaley soils that dry out quickly. The best time to perform frost seeding is early in the morning when the soil is frozen, and a thaw is expected during the day. This reduces the chance for soil compaction while providing the desired soil heaving that improves seed-to-soil contact.

The best species for frost seeding generally are small seeded, germinate quickly, and grow well in cool conditions. Red, white and sweet clover are the most successful species, while birdsfoot trefoil can also be used for pasture renovation despite slower germination and early growth. And though yellow sweet clover can cause animal health problems due to coumarin content (a blood thinner), it is not likely to cause livestock health issues if it is only a percentage in a pasture. When seeding legumes, be sure to inoculate them with the appropriate rhizobium so the symbiosis will take place to fix N. In pastures, some non-fluffy grass species such as annual or perennial ryegrass may also be frost seeded. Do not mix grass and legume seed for broadcast application as the legume seeds will throw farther than the grass seeds due to their greater density, which leads to non-uniform seed distribution.

Make every attempt to guarantee uniform coverage by knowing the width of spread and spacing between passes. Recommended species and seeding rates for the two scenarios discussed here are given in Table 1. Seeding rates into small grains are higher because no repeat application is possible, while with pasture renovation frost seeding complements an already established stand and can be repeated next year if not successful. Heavier seeding rates for pasture renovation would be used in thinner stands. It is common to mix clovers for pasture renovation. Red and ladino white clover make a good combination, where you use twice the seeding rate of red clover as white clover (e.g. 2 lbs/A red + 1 lbs/A white clover up to 6 lbs/A red + 3 lbs/A white clover).

Table 1. Species and seeding rates (pure stands, lbs/A) for frost seeding into winter small grain or for pasture renovation

Species	In small grain	Pasture renovation
Red clover	10-15	4-8
Yellow blossom sweet clover	15-20	5-10
White, ladino clover	NR	2-3
Birdsfoot trefoil	NR	4-6
Perennial or annual ryegrass	NR	4-6

NR = not recommended.

Frost seeding will likely be most successful in pastures with bare spots or those that are overgrazed. Besides relying on the freeze-thaw action at seeding, you can also use grazing animals to tramp in the seed shortly after broadcasting in late winter. This practice may be especially helpful for improving seed-to-soil contact if a thick thatch layer that would compromise frost seeding success is present. However, don't turn out animals in wet conditions and cause soil compaction. If you miss the best 'window' for frost-seeding, clover seed will remain viable in the soil and much of it will likely grow when the conditions are right. If you notice your stand is not adequate in summer, you can selectively no-till legumes and/or grasses in late summer to fill in thin spots to resolve any lingering issues.

Source : psu.edu

Video: Why Your Food Future Could be Trapped in a Seed Morgue

In a world of PowerPoint overload, Rex Bernardo stands out. No bullet points. No charts. No jargon. Just stories and photographs. At this year’s National Association for Plant Breeding conference on the Big Island of Hawaii, he stood before a room of peers — all experts in the science of seeds — and did something radical: he showed them images. He told them stories. And he asked them to remember not what they saw, but how they felt.

Bernardo, recipient of the 2025 Lifetime Achievement Award, has spent his career searching for the genetic treasures tucked inside what plant breeders call exotic germplasm — ancient, often wild genetic lines that hold secrets to resilience, taste, and traits we've forgotten to value.

But Bernardo didn’t always think this way.

“I worked in private industry for nearly a decade,” he recalls. “I remember one breeder saying, ‘We’re making new hybrids, but they’re basically the same genetics.’ That stuck with me. Where is the new diversity going to come from?”

For Bernardo, part of the answer lies in the world’s gene banks — vast vaults of seed samples collected from every corner of the globe. Yet, he says, many of these vaults have quietly become “seed morgues.” “Something goes in, but it never comes out,” he explains. “We need to start treating these collections like living investments, not museums of dead potential.”

That potential — and the barriers to unlocking it — are deeply personal for Bernardo. He’s wrestled with international policies that prevent access to valuable lines (like North Korean corn) and with the slow, painstaking science of transferring useful traits from wild relatives into elite lines that farmers can actually grow. Sometimes it works. Sometimes it doesn’t. But he’s convinced that success starts not in the lab, but in the way we communicate.

“The fact sheet model isn’t cutting it anymore,” he says. “We hand out a paper about a new variety and think that’s enough. But stories? Plants you can see and touch? That’s what stays with people.”

Bernardo practices what he preaches. At the University of Minnesota, he helped launch a student-led breeding program that’s working to adapt leafy African vegetables for the Twin Cities’ African diaspora. The goal? Culturally relevant crops that mature in Minnesota’s shorter growing season — and can be regrown year after year.

“That’s real impact,” he says. “Helping people grow food that’s meaningful to them, not just what's commercially viable.”

He’s also brewed plant breeding into something more relatable — literally. Coffee and beer have become unexpected tools in his mission to make science accessible. His undergraduate course on coffee, for instance, connects the dots between genetics, geography, and culture. “Everyone drinks coffee,” he says. “It’s a conversation starter. It’s a gateway into plant science.”