Importance of soil temperature when planting

Published: May. 13, 2021 at 7:17 PM EDT|Updated: May. 13, 2021 at 7:41 PM EDT
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PRESQUE ISLE, Maine (WAGM) - When it comes to planting, knowing the right time to plant is very important.

“Right now, we are about 2-3 degrees behind our norm,” Steve Johnson, Crop Specialist for the University of Maine Cooperative Extension, said.

During planting season for potatoes, Johnson says 50 degrees is his magic number.

“I’m looking for an average soil temperature of 50, which would be high plus low, divided by 2, average of 50,” Johnson said. “Generally speaking, we historically cross the 50-degree average temperature around the 15, 16, 17 of May.”

Chart for Soil Temperatures
Chart for Soil Temperatures(University of Maine Cooperative Extension)

Johnson says when it comes time to plant, soil temperature is vital.

“We are a little ahead of last year but still this is cool temperatures,” Johnson adds. “One of the reasons I look for a mean of 50 degrees, is that the potatoes don’t grow less than 50 degrees. If they were put in 10 days ago and our soil temperature hasn’t been above 50, they are just sitting there. Frankly with all the pathogens and pests and such in the soil they’re better off in a storage where you’re controlling the environment.”

While some may be planting early, Johnson says its better to wait.

“Warm seed into too cold of temperatures can lead to problems with seed. Again, our seed was aged going into this spring from last year’s weather. Very hot and very dry during harvest. So, this is probably not a time to stress them.”

He adds right now is a good time for rotational crops and small grains, as they can withstand colder temperatures.

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