Soybean Seeding Tips

May 07, 2025

Seeding Date

The window to seed soybeans is flexible throughout the month of May in Manitoba. Aim to seed during the second to third weeks of May to maximize soybean yield while reducing the risks associated with cold soil and late spring frost.

From 2017-2019, Kristen MacMillan, UM-MPSG Agronomist-in-Residence evaluated four seeding windows at Arborg, Carman, Dauphin and Melita. Soybean yields did not differ among seeding dates from May 1 to May 24, but yields were reduced by 15%, on average, when seeding was delayed until May 31 – June 4. Very early seeding, during the week of April 28 – May 6 was risky. Late spring frosts occurred in two years and soil temperatures during this window were as low as 0°C, causing plant stand reductions and reducing yield by up to 19% at some sites. Report →

From 2017-2021, Dr. Ramona Mohr, AAFC-Brandon evaluated two seeding date windows, among other factors like residue management at Carberry, Brandon and Indian Head. Seeding dates of May 8 to 14 increased soybean yield by 11%, on average, compared to later dates of May 24 – 30. Click here for a summary of this research →

Seeding Rate and Target Plant Stand

Target a living plant stand of 140 – 160,000 plants/ac to maximize yield. Take into account expected germination and survivability to calculate seeding rate. In on-farm trials, soybean seed survival has been 81% on average (82% with planters and 80% with air seeders).

MPSG’s On-Farm Network has been evaluating different soybean seeding rates on-farm since 2012. There have been 132 trials comparing soybean seeding rates to date and, most of the time (84%), lowering soybean seeding rates by 30,000 seeds/ac from a farmer’s traditional seeding rate has not changed soybean yield. From these trials, seeding above 190,000 seeds/ac has not provided a consistent return on investment. Generally, seeding rates of 150,000 to 190,000 seeds/ac has maintained soybean yield while minimizing seed costs. Dropping below 150,000 seeds/ac is not recommended since it introduces much more risk, especially in terms of weed control. Report →

Click here to see more...

Video: predictive weed Management saves on herbicide costs and increases yield potential

Gowan Canada is partnering with Geco Strategic Weed Management to help Canadian growers take a strategic approach to weed control through data-driven prediction and planning.

Geco’s technology uses data and AI to map where weeds have been over the past five years and predict where patches are likely to emerge next season. These insights allow farms and retailers to plan ahead and target actions in the most challenging areas.

“Our technology enables the question: if you could know where your most problematic patches are and where they are spreading to, what could you do differently? That’s what our technology makes possible,” said Greg Stewart, CEO of Geco. “Many of our farms are already using our prescriptions along with Gowan products, so this collaboration is a natural next step.”