As gardeners, we can plant successfully season after season without a soil thermometer…as long as we wait to plant until farmers are in the field. Farmers have learned that if you want to start planting as soon as possible, you must consider the soil temperature. This relatively cool, wet spring in this region, highlights the need to know soil temperatures if you try to start the season early. Here’s why.
Some early warm days in mid-March this year encouraged planting snow peas, the ones that you eat pod and all, in containers. Ground soil was not yet easily worked and the containers were convenient to water on the deck.
As the spring unfolded, we experienced an atypical pattern of cool, wet weather for almost two months. Weather is often unstable in spring, but the cool air temperatures slowed the warming of soil, even in containers that respond more quickly than ground soil.
After a month of no germination, the seeds were mush. The soil thermometer registered 65 degrees F. when I re-planted the seed. Farmers watch soil temperatures before they plant to save labor, seed and mechanical costs.
Now the snow peas are growing and peas will probably appear in mid-June. These are hardly earlier than if planted in ground, if they had been planted as soon as the ground temperature warmed to trigger seed germination.
Even in the tiny soil containers in a greenhouse or on your window sill, the soil temperature is not the same as the air temperature. When the greenhouse temperature registered 81 degrees F., the soil temperature in this shallow tray of soil was 78 degrees.
That plants can accommodate to unstable and variable springs to begin new life at a more favorable time is amazing. If you’d like to find out more about soil temperature, please go to this Yankton Press & Dakotannewspaper link where the article was published:
Thanks for visiting Plant Exchange, where we share about plants of the Northern Plains and people who grow them. We hope you’ll enjoy more topics about the kinds of plants you like here. Notice the topics listed below the posts. Thanks to all who have contributed from their growing experiences here. Thanks to all our readers!
Plant Exchange Blog 
You know, except for the thermometers on the old fashioned hot beds in the propagation house, I do not use thermometers. I never have. Of course, soil temperature is not such a concern here as it is in other climates. Regardless, we have never become reliant on such technology.