Planting and early-season corn and soybean progress – 2025 update

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Dry conditions in northern and central parts of Illinois allowed for a relatively early start to planting this year; the first NASS report of planting was soybeans at 1% on April 6. Soybean planting stayed ahead of corn planting through April, with 22% of soybeans and 16% of corn planted by April 27. By May 4, planting progress was nearly even—33% for soybeans and 32% for corn. Since then, corn has pulled ahead, reaching 82% compared to 75% for soybeans on May 25, and 93% versus 86% on June 1.

This was not a switch in priorities as much as the result of having more soybeans yet to be planted than corn in southern Illinois, after May turned wet, and as planting is nearly completed across much of central and northern Illinois. Compared to historical averages, the 50% planted date for corn was about a week later than normal, and the 50% planted date for soybean was about 10 days earlier than normal. But planting progress was relatively smooth and close to normal in most parts of Illinois in 2025. Instead, yield of both crops will depend on seasonal weather patterns.

Crop progress and stand establishment

Overall, crop stands are good to very good across most fields, reflecting the relative freedom from heavy rain, flooding, and crusting after planting. By the beginning of June, corn that had been planted in mid-April in northern and west-northwestern Illinois was just beginning to accelerate stem growth – the process that initiates rapid growth and nutrient uptake. In contrast, cooler-than-normal temperatures had slowed growth in corn planted earlier in May. At a planting date trial in Monmouth (Figure 1), corn planted on April 15 had reached V7 by June 3, having accumulated 612 GDD (130 above normal). Corn planted on May 6 was at V4 on June 3, with 404 GDD (near normal), while corn planted on May 17 was at V2 with 208 GDD accumulated (80 GDD below normal). Warmer weather in the forecast is expected to accelerate crop growth rate, including expansion of leaf area, which will accelerate light interception across fields.

Soybean stands are also in good condition in most fields, though growth has been similarly slowed by cool temperatures. The generally good leaf color across most fields indicates adequate root development for water and nutrient uptake. At the soybean planting date trial near Urbana, soybeans planted on April 17 reached the V4 stage by June 4, those planted on May 9 were at V1, and those planted on May 17 were just emerging (Figure 2).

Once soybean plants reach the V1 stage, the rule of thumb is that they typically produce a new node on the main stem about every 3.7 days under normal conditions/temperatures, or about two nodes per week. This means that early-planted soybeans could reach the V8 stage by the summer solstice (June 20 this year), with the potential to begin flowering around that time. In contrast, soybeans planted in mid-May will remain several stages behind and are unlikely to flower by that time. While there has been a lot of talk about the advantage of having soybeans set their first flowers by or before the solstice, this does not always happen even if soybeans are planted in mid-April.

As an example of how random soybean flowering can be, we reported in an article here a year ago that soybeans planted in mid-April were at V4 on June 4, not yet flowering. They did flower by June 20, but only after high temperatures averaged above 90 degrees, and daily low temperatures of 68 degrees, for the week before June 20. If temperatures remain cooler than that this year, flowering will probably not begin until after the longest day of 2025.

Managing late-planted crops

While the most significant variable affecting yields of late-planted crops will be weather, certain management strategies can help mitigate risk and optimize yield potential. Here are key considerations:

Corn hybrid: The median (50% chance) first frost in southern Illinois typically occurs around October 25. If that holds true in 2025, most late-planted crops should reach maturity by that time, as long as hybrid selection is adjusted accordingly. Southern Illinois generally accumulates around 2,800 GDD between June 1 and September 30, and about 2,500 GDD between June 15 and September 30. This range would be enough for 108-112 RM hybrids to mature by the end of September, and to have some drying weather after that. Planting hybrids with varying maturities can help spread the harvest schedule and reduce the risk of the entire fields encountering stress (such as drought and heat) during critical periods like pollination and grain filling. The Corn Growing Degree Day (GDD) decision support tool can aid in this decision. As an example, a 112-day RM hybrid (which the tool estimates will need ~2,700 GDD from planting to maturity) planted on June 10 in Franklin County, IL, is projected to mature on October 3. GDD accumulation slows as we move into October, which also slows grain drying.

Soybean variety: While the ultimate impact of late planting remains a bit of an unknown at this point, one thing is clear: late planting is not a recipe for disaster like it used to be. We’ve seen in previous years that late-planted soybeans can still yield very well—often reaching 80 to 90 bushels per acre in some instances. Data from the University of Illinois Variety Testing Trials in Belleville (Figure 3) shows that early-to-mid MG 4 varieties tended to optimize yields in recent years when planted early to mid-June, with little to no yield benefit in pushing to late MG 4s.

With wheat harvest likely to be a little later this year than in some recent years, double-crop soybean planting may be delayed as well. There should be no need to change management if the delay is less than a week or two. Previous research has shown that soybeans planted as late as mid-July in central Illinois and late July in southern Illinois have a chance to produce good yields, although that chance diminishes as planting gets later.

Row spacing and seeding rate for soybeans: Although we have not seen much evidence that 15-inch rows have consistently out-yielded 30-inch rows, a quicker canopy closure can benefit the crop by improving light interception, reducing weed suppression, and helping to conserve soil moisture. Late-planted soybeans tend not to need much higher seeding rates than early-planted ones, but there may be a benefit to slightly increasing rates. We’ve heard a few reports of fields with sub-optimal stands, which should be supplemented by planting more seed without destroying the existing stand. Our research shows that having harvest populations of about 110,000 to 120,000 tends to maximize return to seed.

Is the start of the season a key predictor of final yields?

Not necessarily. Although experience has taught us that crop ratings in June often have little bearing on final yield, it is worth noting that crop ratings in Illinois, first released this year on May 25, are not as high as we might have expected for crops that were planted under good conditions and with near-normal planting progress. On June 1, Illinois corn was rated as 63% good + excellent, while Illinois soybeans were at 59%. In contrast, Iowa corn was at 84% and Iowa soybeans at 81% G+E. Why the difference? More of Iowa stayed dry during much of May, which allowed planting to be completed earlier. Both states have sizeable areas of abnormally dry or moderate drought. Based on data through June 3, the U.S. Drought Monitor released on June 5 shows 72% of Iowa as abnormally dry and 13% in moderate drought; the numbers for Illinois are 54% abnormally dry and 25% moderate drought. Rainfall this week has lowered these percentages in both states.

As remaining acres get planted in Illinois, provided that no serious problems such as widespread flooding take place, we expect the ratings in Illinois to increase in the coming weeks. As a reminder, ratings for both crops plummeted in Illinois in 2023 as drought increased in June 2023, then they rebounded to near normal (although more for soybeans than corn) by August, and yields were good for both crops. We don’t want soils to dry out too much in June, but the less standing water we get over the next month, the better the crop potential will be. Reaching that potential, as always, will require that rain adds enough water to the soil to keep the crop supplied through the rest of the season.