This map shows soil temperature at a 2-inch depth across the state of Kansas. The table below includes seven-day minimums, maximums and averages as well as corresponding temperatures at a 4-inch depth. Though this resource isn’t precise to your specific location, it does give a glimpse of what is happening nearby. Why does this matter?
Soil temperature affects germination rate. Peas can sprout in soil that is 40 degrees F. Lettuce can germinate in soil down to 35 degrees F, though it performs better at 45 degrees F. However, crops such as tomatoes, corn and other warm-season veggies need the soil to be at least 55 degrees F for success. Peppers, cucumbers and melons need even warmer soil (60 degrees F).
The Kansas Mesonet is a great resource for guidance on what’s happening below the ground. You can also take your own soil temperature measurements using a soil thermometer. Measure the soil at least 2.5 inches deep, during late morning. Find the average soil temperature over five days to determine when the time is right for planting. It is still important to watch the forecast for late season frosts and freezes.
(Kansas Mesonet, 2024: Kansas Mesonet Historical Data. Accessed 23 February 2024, http://mesonet.k-state.edu/weather/historical)