If your soil thermometer is reading inaccurately, please refer to the accuracy testing and calibration procedures listed below.
Accuracy Testing Procedures
If the thermometer is reading incorrectly, there are two ways that you can test for accuracy, then calibrate based on your results.
The first method is to fill a container with mostly crushed ice and some water. Wait approximately 1 minute. Insert 2" of the probe into the mixture of water and ice for 10 seconds or until the temperature reading does not change. The unit should read 32˚F.
The second method is to bring a pot of water to a rolling boil. Insert 2" of the probe into the boiling water for 10 seconds or until the temperature does not change. Being careful not to touch the probe to the side or bottom of the pot. The unit should read 212˚F.
First, perform one of the above accuracy tests. Without removing the probe, grip the adjusting nut with a suitable tool and rotate the thermometer to correct the error. Allow a minimum of 30 seconds before readjusting.