Tuesday, April 6, 2010

Soil Temperature

Joe and I went on a walk with the Mushroom Club of Georgia on Saturday. This should be prime morel time. However, people in the group who've been mushrooming for long enough to have "usual places" to check for morels have been checking, and not found any. We were lucky, though, and found a few White Morels (a new species for the group!) on our walk.

One woman in the group had brought a digital meat thermometer, the kind you can get at a grocery store, and stuck it in the ground to check the soil temperature. The thermometer showed a reading of 55 degrees F, which is near the lower end of the range for morel season (which come up in the range 53-60 degrees), but still should be a good temperature.

I had never thought of getting a regular food thermometer for checking soil temperatures, but it seemed to work just fine! This would be useful for gardeners, too. We've had a cold winter, with fewer than usual warm days between the cold ones, and many spring flowers have been slow to come up. I have thought that the soil was just too cool to trigger their emergence.

This year, soil temperature might be a more useful tool than the calendar in deciding when to plant seeds!

Arizona Cooperative Extension has published a chart showing ideal temperatures for germination of many garden crops. Although many will germinate below 55 degrees, the ideal temperature for germination of many crops is 75 to 85 degrees. I don't think, though, that I'm going to wait for the soil to get quite that warm.

The average date of our last frost is the 15th, but I usually wait to plant the summer crops until the 20th, when I am really sure that there is no more danger of frost. This year, I might also go get a thermometer and check the soil temperature, too, to make sure that it is absolutely a good time to plant, before putting the summer crops in the ground.


  1. I use a regular food thermometer too, mostly because I'm cheap and lazy sometimes, LOL!

  2. Erin,

    We had a work day at the Plant a Row for the Hungry garden on Wednesday, and one of my friends brought her thermometer from home. The soil temperature was 56 degrees F, so we are getting close to planting time!

    My meat/candy thermometer is an old, non-digital type that takes a long time to register the temperature. I am going to pick up a digital version later today, when I am out on errands.

    Looking forward to getting all my seedlings into the ground!


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