Soil temperature is important for germination in the garden
Home gardeners can take their own soil temperature measurements, says K-State expert
At a glance: Different plants require different soil temperatures to germinate, says K-State horticulture expert Matt McKernan.
More information: Matt McKernan, hortsupport@ksu.edu
Related: K-State Horticulture Newsletter | Kansas Mesonet (Soil Temperature)
Home gardeners can take their own soil temperature measurements, says K-State expert
Feb. 18, 2026
K-State Extension news service
MANHATTAN, Kan. — Just in case home gardeners have not really considered the importance of soil temperature, Kansas State University horticulture expert Matt McKernan says you should. Soil temperature, he says, affects germination of many vegetable garden crops.
McKernan said peas can sprout in soil that is 40 degrees Fahrenheit, while lettuce and onions can germinate in 35 F.
“Crops -- such as tomatoes, corn, green beans and other warm-season veggies -- need the soil to be at least 55 F for success,” McKernan said. “Peppers, cucumbers and melons need even warmer soil.”
The Kansas Mesonet is a resource for guidance on what’s happening below the ground. McKernan said gardeners can also take their own soil temperature measurements using a soil thermometer, and measuring 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,” McKernan said. “It is still important to watch the forecast for late season frosts and freezes that may impact seedling growth.”
McKernan and his colleagues in K-State’s Department of Horticulture and Natural Resources produce a weekly Horticulture Newsletter with tips for maintaining home landscapes and gardens.
Interested persons can subscribe to the newsletter, as well as send their garden and yard-related questions to hortsupport@ksu.edu, or contact your local K-State Extension office.
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K‑State Extension is a short name for the Kansas State University Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the wellbeing of Kansans. Supported by county, state, federal and private funds, the program has county extension offices statewide. Its headquarters is on the K‑State campus in Manhattan. For more information, visit www.ksre.ksu.edu. K-State Extension is an equal opportunity provider and employer.