Late-Spring Frost Damage to Corn and Soybeans

Written collaboratively by David Karki and Jonathan Kleinjan, former SDSU Extension Agronomist.

Due to warmer winter and spring, row crop planting has been relatively early in South Dakota. As of May 17, 2026, 80% of corn was planted with almost 20% reported to be emerged (USDA, NASS). Soybean plantings were reported at 60% with 10% emerged (USDA-NASS). Early planting may increase yield potential in some years but also puts crops at risk for damage caused by early-season or late spring low temperatures. Several days with temperatures lower than 32 °F were observed in the last two weeks. While a relatively low percentage of crops planted are likely to emerge this time of the year, producers may still want to evaluate individual fields for crop damage. Some locations (especially low-lying areas) will likely see lower temperatures than those recorded by the weather stations.

Impacts on Plant Growth

Corn emerging in a no-till field in late spring.

One common question we face is: what is the difference between a frost and a freeze? A frost event occurs when the temperature of the soil surface is 32° F or lower, while a freeze occurs when the air temperature is 32° F or lower at five feet above ground level. It is important to remember that, if atmospheric conditions are right, it is possible for frost to occur even when air temperatures are slightly higher than freezing. While mild frost should cause minimal damage to young crops, a hard freeze (28° F or colder for 2 hours) will most likely be damaging if not lethal.

The growing point of corn plants remain below the soil surface until V6 growth stage (the plant is approximately 1’ in height) and is generally considered safe from freezing air temperatures. However, if air temperatures remain below 28°F for more than a few hours, the growing point may be injured or killed regardless, as the lethal cold may penetrate the upper inch of soil. This is more of a concern when soil conditions are dry.

Soybeans are more susceptible to low temperatures due to the fact that the growing point is above ground as soon as the crop emerges. The soybean plant develops axillary buds at each leaf node, including the cotyledons. If any of these buds survive a low temperature event, recovery is possible. However, if the plant is damaged below the cotyledons, seedling death will follow.

Assessing Plant Stands

Immediately following a frost or freeze, leaves on young corn and soybean plants may initially blacken and then become necrotic (wither and turn brown). This is not the time to make decisions about replanting. The actual extent of damage should be assessed 3-5 days after the event or when a few days of favorable growing conditions have returned. Corn plants that will survive should either have new leaf tissue emerging from the whorl or a growing point that is white/light yellow and firm. The growing point can be observed by splitting the seedling lengthwise and examining the area ½ to ¾” below the soil surface. A decayed and discolored growing point indicates a dead plant. Soybean plants should have new leaf tissue emerging from one or more of the undamaged nodes. Plants that still look dead at this point will probably not recover.

A careful assessment of plant stands should be made prior to making replanting decisions. Good yield potential still exists when stands are reduced by 20% for both corn and soybeans. However, stands should be somewhat uniform. When scouting for crop damage in fields with varying topography, keep in mind that frost damage is typically more severe in low-lying areas, as cold air tends to flow into depressions. In other words, some areas of the field may warrant replanting while others do not.