A $60-Per-Acre Risk: The High Cost Of Switching Corn Hybrids Too Early

Data shows late-planted corn can “cheat” the clock with GDU acceleration, making the case for holding the line on your original hybrids for now.

By Rhonda Brooks

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May 20, 2026 01:10 PM

Corn planting is 76% complete, and soybeans are 67% complete — both are ahead of the five-year average. Despite the record pace, farmers in some parts of the country have hit a planting logjam because of too much moisture or not enough.

According to the USDA’s weekly Crop Progress Report released on May 18, 2026, the nationwide planting pace for both corn and soybeans is running well ahead of historical averages:

The national snapshot shows:

Corn: 76% complete nationwide (6 points ahead of the 5-year average of 70%).
Soybeans: 67% complete nationwide (14 points ahead of the 5-year average of 53%).

While farmers in much of the country are cruising through planting, in several regions farmers are battling with weather. Rain and wet soils have created at least three logjams across the Corn Belt:

1. The Great Lakes Region, specifically Michigan & Northwest Ohio
2. Mid-Mississippi Valley, especially Missouri
3. Isolated Pockets of parts of Illinois

At the other extreme: much of the western U.S. and the Southeast are still being hammered by drought conditions.

Corn Strategy: Stick To The Plan (For Now)

As calendar pressure builds, farmers will start to consider switching corn hybrids and soybean maturities. However, Mike Hannewald, field agronomist for Beck’s Hybrids, warns that abandoning your original corn and soybean plans could be the biggest mistake you can make right now.

“We want to stick with the original plan, unless we’re really doing something extreme with 115‑day corn, or something excessive like that,” says Ohio-based Hannewald.

Here is why the data says you should hold the line through the rest of May, if you are in the Corn Belt:

The GDU “Cheat” Code: Research from Ohio State and Purdue University shows that for every day after May 1, there is a 6.8 Growing Degree Unit (GDU) reduction in the total number of GDUs corn needs to reach black layer. The corn detects it is late and actually accelerates its vegetative growth, writes Bob Nielsen, former Purdue University Extension corn specialist and professor emeritus.
The ROI on Full-Season Genetics: Granted, late-planted corn will be wetter at harvest, but Practical Farm Research (PFR) data shows the yield advantage of fuller-season hybrids will cover the drying costs and then some. The 3-year study factoring in drying costs at 4 cents per point revealed significant penalties for switching to early maturities too soon. As indicated in the chart below, going from a 112-day hybrid to a 105-day hybrid reduced net return by $63. Some of the other options show more extreme results.

Hannewald draws the line at June 1. Once June arrives, he says it’s time to run GDU calculations to ensure your corn crop can reach black layer before the first fall frost for your area.

Soybean Strategy: Keep Maturity, Push Populations

For soybeans, Hannewald’s advice is identical on maturity but carries a critical management twist: leave your varieties in place, but crank up the seeding rate.

He says the data shows full-season bean varieties consistently out-yield short-season options because they have more calendar time to grow. However, late-planted beans lose time to build critical nodes and pods. To compensate for that issue, he tells farmers to pull the population lever.

Starting about now (May 20), he advises increasing your soybean planting population by 10,000 seeds per acre, per week. For example:

Week of May 20: If your base is 130,000, bump to 140,000.
Following Week: Bump to 150,000, and so on.
The Ceiling: Top out around 200,000 for a planter, or 220,000 for a drill if planting drags deep into June.

Shawn Conley, Extension soybean and small grains specialist at the University of Wisconsin, has a different perspective. He says most farmers should stay with about 100,000 to 140,000 seeds per acre if planting late but to narrow up your rows, if possible.

6 Soybean Seeding Rate for Lateish planting.jpg — Optimal seeding rate for planting would be 100,000 seeds per acre, even in mid-May, according to Shawn Conley. “But, that really doesn’t take into effect delayed canopy and management of waterhemp,” he notes. For replanting considerations, Conley says he tells farmers that unless they have under 60,000 plants per acre and actively growing, his advice is “don’t do anything.”

The Golden Rule: Conditions Trump The Calendar

Even though the clock is ticking, Hannewald reminds growers that “mudding it in” is a losing proposition for planting either crop.

“Planting too wet into poor conditions and causing uneven emergence actually costs us more later in the season than what it did early, and that plays true for both corn and beans,” he says.

Learn more of Hannewald’s take on how to evaluate whether to switch corn hybrids and soybean maturities at the video here.

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