Garden Soil Thermometer Probe - Useful Soil Temperature Probe To Measure Temperature of Soil Prior To Sowing and Planting 155mm garden soil thermometer probe assists with seed propagation by indicating soil temperature. This soil temperature probe is printed with an easy to read green temperature scale on a white plastic moulding. This soil thermometer probe is a handy tool for the gardener to monitor soil temperature prior to sowing and planting out.