Of Seeding Dates, Rates, and Even More Delays...

May 18, 2022

Should you increase your seeding rates of spring wheat as seeding is delayed yet again? The short answer is 'Yes, you probably should. There are two approaches to determining how much seed you should commit to the seedbed. The physiological underpinnings and thus reasons for doing so are the same in both approaches. The suggested seeding rates that each approach yields do not differ that much but are reported a little differently.

To understand why you need to increase your seeding rate, I refer you to the post I posted earlier today. As seeding is delayed, the crop will go through its paces faster and reach each developmental stage sooner. This includes the initiation of tillers. Later seeding will result in fewer tillers being initiated and increasing your seeding will offset the loss of tillers and thereby partially offset the yield loss of the delayed seeding.

The conventional rule of thumb was to increase the seeding rate enough that the initial stand is increased by 1 plant per square foot or about 3.5% for each week seeding is delayed past the optimum planting window. To attain that increase in the initial stand you need to increase your seeding rate not just by 3.5% but by 5% in the first week and at least 10% in the second week. The reason for this is that stand losses (viable seed that does not emerge as a seedling) increase as seeding rates are increased. My research in the mid-nineties suggested that the optimum and maximum seeding rates for each variety somewhat differed and there was not much benefit to going higher than an initial stand of 34 to 36 plants/ft2.

A few years ago J Stanley's Ph.D. research revisited the work I had done in the early nineties. He took a different approach by not looking at the initial stand but the number of live seeds per acre that maximized grain yield in a given environment. His dataset included much larger geography that spanned from southern Minnesota to western North Dakota. His decision key ( Figure 1) takes the expected yield, straw strength, and tillering capacity of the variety into account.

At first glance, the suggested seeding rates run counter to the older rules. The lower yield potential category included more environments where water was the first rate-limiting factor not delayed planting. When looking at the moderate and high-yielding environments, the suggested seeding rates come much closer to the older rules when considering that stand loss increases as seeding rates are increased. Later planting, for example, will generally result in a shorter crop that is less prone to lodging, thereby allowing you to increase the seeding rates more if your variety is more prone to lodging. A seeding rate of 1.6 million live seed yields about 33 plants per square foot if you assume about 10% stand loss.

Figure 1 - Decision tree for determining the optimum seeding rate for different varieties and expected yield potential in Minnesota and North Dakota.

Source : umn.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.”