Using A Soil Thermometer to Plant By

On Earth Day today it seemed fitting to have my hands in the soil so I planted two varieties of snow peas. Yes, it is early to plant seeds in SW Michigan, but this season I am being a bit more scientific in my garden planting approach than in previous years.
What this means is, I am using a soil thermometer to determine when to plant my seeds.
I ordered my seeds from Territorial Seed Company and one of the reasons I selected this company is because their seed packets have the soil temperature needed printed on each packet. Snow peas like cooler temperatures so they can be planted when the soil is between 40 and 65 degrees. I calculate that we have one more frost to go and since pea seeds will take two weeks to germinate and they actually like cool weather, I am willing to risk planting them early.
My thermometer is marketed as a compost temperature gauge but I see no reason that I cannot also use it to test the temperature of the soil. I choose the model with a stainless steel 20” long gauge and a sealed dial that is waterproof so it can be used to test the soil in my raise beds as well as my huge compost pile. This thermometer measures from 0 to 220 degrees F and tells me if my compost is hot enough when the compost is cooked.
We purchase this thermometer from Reotemp Instruments, It has rugged all stainless construction with a plastic lens, a 20” pointed stem for east insertion and can read temperatures from 0 to 200 degrees F.
Another nice thermometer option is the clip style from Johnny’s Selected Seeds, 1-877-564-6697 that slips into a pen like casing that clips to a shirt pocket or waist band. This type reads from 0 to 220 degrees F. This style is product ID 9069 and is marketed as a “quick response of a bimetal thermometer with calibrated accuracy.”
It’s been fun to experiment with this new tool and I know my granddaughter will have fun with it as well.
A close up of the Reotemp thermometer face with its easy-to-read dial.
The thermometer in its original packaging. You can get a feel of this style 20" length.
Explicit packaging help gardeners to judge when it is time to plant seeds. Planting details are on the back of the seed packet.
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  • Douglas Hunt Douglas Hunt on Apr 26, 2014
    I suspect many plantings would be more successful if we took the temperature of the soil first. Caladiums, for example, want a minimum soil temperature of 65 degrees.