When harvest or fall fieldwork gets delayed, winter wheat planting can slide down the priority list. While it’s tempting to think you can make it up later, the hard truth is this: you can’t buy back that time.
Dennis Pennington, Michigan State University (MSU) Extension wheat specialist, has run the numbers. In MSU field trials, he found that delaying planting just two weeks beyond the optimal time costs nearly 30 bushels per acre, on average — and no amount of seed, fertilizer, or management effort can bring those bushels back.
“I don’t know of any other trial or product or management practice where you’re going to see a 30-bushel response,” Pennington says. “Using an optimal planting date is the single most important thing you can do.”
What 30 Bushels Looks Like Before Winter
In 2025 field trials, Pennington’s team planted wheat on five dates from mid-September through mid-November, spaced two weeks apart. In December, they dug up plants from each of the five dates to see what the crop accomplished before going dormant.
The differences were dramatic.
They found early-planted wheat (by around October 1 in Michigan) heads into winter with at least three tillers per plant. Planting only two weeks later? Zero tillers.
That’s not just a cosmetic difference occurring during that two-week period — it’s yield potential that is lost and can’t be recovered.
Pennington and team tested five seeding rates from 0.8 million to 2.4 million seeds per acre at every planting date. They found the earlier plantings consistently hit 160 bushels per acre, and those yields barely budged whether they planted 0.8 million or 2.4 million seeds per acre.
But when pushing planting dates later, yields dropped to around 130 bushels per acre or less. The result was typically a 30-bushel haircut before spring ever arrived.
More Seed Helps, But It’s Not Yield Recovery
Cranking up seeding rates can help compensate for lost fall development. But yield compensation isn’t the same as yield recovery.
In Pennington’s November 15 planting, wheat hadn’t even emerged by December. At lower seeding rates, yields were at below 80 bushels per acre. Pushing populations to 2.4 million seeds improved yields to around 100 bushels.
That’s better, but it’s still 60 bushels short of what timely planting alone delivers.
“We used to say if you’re planting later, increase your seeding rate to offset the yield loss,” Pennington says. “Well, yes, it does help … but you’re never going to get back to what your original yield potential was.”
It’s About Productive Wheat Heads, Not Green Cover
Why does planting date matter so much? Because yield comes from productive wheat heads per square meter, and that starts with what happens before winter.
After emergence, wheat develops primary (first-order) tillers. These tillers have their own root systems and can support productive heads. Later, the plant produces secondary tillers, but those still depend on primary tillers for water and nutrients, and secondary tillers are typically still less productive, Pennington notes.
The goal with timely planting isn’t just about establishing a thick wheat crop by November, he adds. It’s about establishing strong plants with productive tillers that will survive winter and contribute heads at harvest.
Give the plant enough time in fall, and it builds the architecture to carry yield higher. Take that time away, and there’s no making it up, Pennington reports.
When Narrow Rows + Lower Populations = More Bushels
Pennington’s research reveals another yield lever: how you distribute seed across the field atplanting is important.
He says top-performing wheat growers in Michigan State’s Yield Enhancement Network (YEN) are doing something counterintuitive: narrowing rows while simultaneously lowering seeding rates.
The strategy gives individual plants better spacing and more room to develop productive tillers.
Pennington’s team compared 5-inch, 7.5-inch, 10-inch, and 15-inch rows. He found that moving to a 5-inch row spacing delivered an advantage of:
- +10.5 bu./acre compared with 7.5-inch rows
- +13.6 bu./acre compared with 10-inch rows
- +27 bu./acre compared with 15-inch rows
“Going to a wider row spacing really is going to lower your yield potential considerably,” Pennington says. “And narrowing to 5 inches will increase the yield even above the 7.5 inches.”
He adds, that for farmers who use or are thinking about using a soybean planter for planting wheat, those numbers should give you pause.
Better Spacing = Better Roots = More Yield
Why do narrow rows work better?
Traditional drills and some air seeders leave wheat concentrated in clumps with gaps between plants. Precision planters place seed more uniformly, approaching equidistant spacing.
“If we can maintain equidistant spacing between the seeds, we’re going to have an impact on the way the roots develop,” Pennington says.
The goal, he adds, is encouraging roots to spread laterally through the upper soil profile, where the majority of the available water and nutrients are located. Better roots support more productive tillers, which produce more heads per square meter and, ultimately, more yield.
You can watch Pennington’s recent presentation on the topic of achieving higher winter wheat yields through early planting and narrow row spacing at the link below:
