Chilly weather has slowed corn planting significantly this spring as Minnesota farmers await higher temperatures to dry and warm the soil.

A weekly crop progress report this week shows that only 12 percent of the corn was planted in the state before May 1, compared with the five-year average of 36 percent by that date and 57 percent during last year’s early spring.

Barley, oats and spring wheat also are well behind schedule for planting, the USDA report said.

University of Minnesota Extension educator Dave Nicolai said that for corn to get a good start, soil temperatures need to be at least 50 degrees Fahrenheit two inches below the surface where the seeds are planted.

Soil temperatures were warm enough in late April to plant in some areas, he said, but then cold weather, rain and snow arrived and soil temperatures dropped back into the 40s.

The result is that it will take a few more days before most farmers can get into the fields to plant, Nicolai said.

“We’re really going to count on this weekend and the following week to warm things up,” he said. “It will be like rush hour out in the fields trying to get the crop in.”

An Extension newsletter this week said that maximum corn yield can still be obtained when planting occurs by mid-May, and in most cases begins to decline when planting is delayed later than that. If planting cannot happen until the end of the month, it said, growers might consider switching to hybrids that need less time to grow, thereby reducing the risk of corn freezing in the fall before it has reached maturity.

Nicolai said it’s too early to tell whether corn already planted this year has been damaged by the unusually cool weather, and that it may be another week before farmers can scout their fields and inspect the emergence and condition of plants.

Many corn farmers also plant soybeans, Nicolai said, which are typically planted after corn in early May. The late corn planting may also push back soybean planting, he said, but that should not begin to affect yields much unless the bean seeds don’t get planted until very late this month or into June.

Minnesota Corn Growers Association spokesman Brent Renneke said that farmers in southeastern and southwestern Minnesota have had different amounts of rain and snow during the past week, but most are not worried about how delays will affect crops this year.

“Generally the mood is positive and optimistic so far,” he said.

New technology and larger machines allow many growers to plant most or all of their corn in a few days or a week, Renneke said.

“They’re not too concerned about catching up if they can get rolling Sunday or early next week,” he said. “There’s lots of sun in the forecast, so things are turning around.”

Last year Minnesota corn and soybean farmers enjoyed record harvests and yields, thanks in part to spring weather that allowed earlier planting and adequate rains during critical times of the summer growing season. However, the bumper crops in both 2015 and 2016 created surplus grain in the market that has kept prices low, in some cases below the costs of production.