Weather Delays Corn Planting but Optimal Window Remains Open

Planting date: University of Minnesota studies show that corn yield is typically maximized when planting occurs from late April through mid-May. In research conducted at Lamberton, Morris, and Waseca from 2009 to 2011, corn yield was maximized when planting occurred between April 25 and May 15. In long-term research conducted at Lamberton from 1988 to 2003, corn yield was maximized when planting occurred from April 21 to May 6, and reduced by just 5% when planting was delayed until May 15. Minnesota corn growers have achieved good yields in the past several years even when the average corn planting date (50% of the corn planted in the state) has been April 29 for the years 2014-2016 and May 7 in 2017.

Hybrid maturity: Although planting delays raise questions about when to switch to earlier-maturity hybrids, a general guideline in Minnesota is to stay with planned choices unless planting is delayed beyond the third week of May. When planting occurs between May 25 to May 31, a hybrid that is 5 to 7 relative maturity units earlier than full-season for the region is suggested to reduce risk of corn freezing in the fall before reaching maturity. 

 

Keep in mind what your starting point is for hybrid maturity. Many farmers plant hybrids that are not quite full-season for the area to limit drying costs after harvest Switching to an earlier-maturity hybrid too early could reduce yield potential. Other considerations include: 1) the number of corn acres one intends to plant and time required to plant these acres, 2) labor availability during planting, and 3) availability and suitability of earlier-maturity hybrids for your farm. 

Planting corn for grain after May 31 in Minnesota carries high risk of reduced yield and test weight and increased harvest moisture and dockage at the elevator. If corn must be planted after May 31 in Minnesota, planting a hybrid about 15 or more relative maturity units earlier than full-season for the region can help reduce risk. At June 5 or later, a crop other than corn should be considered, although this decision will need to be evaluated on a field by field basis. 

Soil conditions: Although timely planting is important, it is also important to avoid planting when soils are too wet. Sidewall compaction and poor seed-to-soil contact (cloddy soil structure) can result in poor root growth and poor stands. Even though soil temperatures may be cold now, by the time the snow melts, fields dry, and soils are dry enough for planting, it will be late April to early May and warmer soil temperatures are expected soon afterward. Unless cold weather is forecast soon after planting, soil temperature should not greatly influence this year’s planting decisions in Minnesota. 

Minnesota weather forecast (optimism for the short term): According to the National Weather Service, springtime conditions are in the forecast for the next week. At this time, the only real risk of precipitation for the next seven days is on Tuesday, April 24, with the outlook calling for a quarter to a half inch of precipitation over southern and central Minnesota. The snow pack that remains will rapidly erode with high temperatures in the 50's and 60's, and overnight lows above freezing. 

The longer range picture from eight to 14 days from the Climate Prediction Center for the period ending May 3 has normal-like temperatures, which for early May means high temperatures in the mid 60's and lows in the mid 40's. There is a chance, however, of above normal precipitation from April 27 to May 3. 

Additional resources: For more resources about corn production, visit Extension’s corn production website: www.z.umn.edu/corn.