Soil Temperature and Plants

Thankfully, it looks like we are finally headed towards spring weather. This means gardeners are ready to get started planting. Is it time yet?

Typically, our last frost-free date is after April 15 for our area. Obviously, this changes from year to year. Along with air temperature, soil temperature plays a role in the success of both flowers and vegetables.

Warm season vegetables like tomatoes and peppers prefer 65oor higher while cucumbers and squash require 70o and higher. Flowers are the same they prefer soil temperatures between 60-70o to promote good root development.

How do you determine soil temperature? You can take a household thermometer and stick it in the soil. Be sure to get it down to what would be root level for accurate readings. You can also check out the Kansas Mesonet which has a station in the southern part of the county.

It is important to remember that soil moisture has a direct effect on soil temperature. Moist soil takes longer to heat up, but it also retains the heat for a longer period than dry soils. With the recent rains and some warm sunny days those moist soils should warm up and retain that heat better.

There are ways to speed up the increase in soil temperature. You can remove mulch or plant residue. The dark soil will absorb light and convert it to heat. Another option is to cover the area with a plastic sheet, either clear or black, which can really heat things up on the sunny days we have been having.

Reach out to the me if you have any other questions. I can be reached at jlcarr@ksu.edu or 620-842-5445.