There have been scattered reports from southeast Manitoba of a few fields of wheat seeded but, for the very most part, no one has turned a wheel in 2026 thus far. But, I see air drills and planters parked in every yard I drive past and speculation of when seeding will start is part of every conversation I have . And while snow can still be easily found in treelines here in Beausejour and standing water in fields is also easy to spot, my past experience mixed with my intuition makes me think this going to be one of those years where seeding is held back until the weather shifts dramatically and then it will be off to the races for everyone. In case my gut feeling turns out to be right, we should explore what we know about determining when to seed soybeans
What does the Research Say?
Fortunately, Kristen McMillan, MPSG Agronomist in Residence at the University of Manitoba, and her team have done extensive Manitoba based research on this question.
Over three years (2017–2019), experiments were established at Arborg, Carman, Dauphin and Melita. Four seeding windows were tested: very early (April 28–May 6), early (May 8–14), normal (May 16–24) and late (May 31–June 4), using the short-season variety, S007-Y4 (MG 00.5),and the mid-season variety, NSC Richer (MG 00.7). Soybeans were seeded into soil temperatures as low as 0°C.
There were no differences in soybean yield when planted throughout May 1 to 24 (Figure 1). Yield was reduced by 15%, on average, when seeding was delayed until May 31 to June 4. These results indicate that the soybean seeding window is flexible during the first three weeks of May in Manitoba.
At four of 11 site-years, yield was maximized by seeding very early (April 28–May 6), but yield was significantly reduced by this very early seeding at one site-year. At five of 11 site-years, yield was maximized during the early seeding window (May 8–14). These results highlight the risks related to seeding soybeans too early in
Manitoba. Cold soil temperatures within the first 48 hours of seeding can result in chilling injury, reduced or delayed emergence and increased susceptibility to soil-borne pathogens. There is also the risk of exposure to spring frost, which can kill or injure emerged seedlings. The coldest soil temperatures occurred during the very early seeding window at Melita in 2019 (0°C), at Melita in 2017 (1.1°C) and at Arborg in 2018 (5.8°C). At those siteyears, yield was reduced by 13–19% during the very early seeding window (April 28–May 6). Late killing spring frosts occurred on May 19, 2017 and June 2, 2019, that may have negatively impacted emerged seedlings and yield from the very early seeding window.
Take Home Points for the Farm
The four factors to consider when deciding if it is time to seed soybeans are: calendar date, soil temperature, the 24 hour weather forecast and your personal risk tolerance (a combination of your nerve and the acres you need to cover).
Calendar date – Aiming to plant during the second and third weeks in May maintain high yield potential while reducing frost risk. A rule of thumb for early planting is to seed within two weeks of the last spring frost date to ensure seedlings are not injured by frost after emergence. Emerged seedlings can tolerate air temperatures of -2.2°C for a brief period if plants have had a chance to harden, but cannot recover if the main growing point is killed. If the growing point is only slightly injured, growth may resume from the axillary buds. Unfortunately, I have found that plants that do resume growth from their axillary buds rarely reach the yield potential of undamaged plants within the same field. Obviously, avoid planting in June due to lower yield potential.
Soil temperature – Soybeans emerge within 24-35 days when seeded into 6-12°C soils and 4- 16 days when seeded into 14-22°C soils (based on soil temperatures at a 5 cm depth at 10:00 a.m. for two consecutive days). Warm soil temperatures result in faster emergence and prevent the risk of chilling injury during imbibition. Residue management should have a minor impact on plant population and yield if soybeans are seeded during optimal calendar dates and into warm soil. Bottomline – try to avoid seeding into soil temperatures below about 8°C.
24-hour forecast – Seeds imbibe water within the first 6- 24 hours after seeding. Try to avoid chilling injury and delayed emergence by delaying seeding if it sounds like the first 24 hours after planting will include low temperatures combined with cold rains or snow. After years of not seeing chilling injury, we definitely experienced it last year in eastern Manitoba.
Personal risk profile – Everyone has a different tolerance for risk so figure out where you stand. The research demonstrated high yields with very early seeding but it also showed that yields were just as high when seeding during the second and third weeks of May. Remember that the research also demonstrated soybean yield could be hit hard with very early seeding if killing frosts or seed chilling injury occurred. At the same time, If you have 1000’s of acres of soybeans to plant, bear in mind that not all of that crop can be planted into ideal conditions. In this scenario, the research definitely shows that starting on the early side is a better bet that seeding very late. June seeding is the most reliable way to lower yield potential in soybeans in Manitoba. And obviously, ensure more frost tolerant crops are seeded before soybeans.
I wish you all good luck and a safe start to the 2026 growing season. Let the race begin!!