“Historically, the recommendation has been to start planting when you have a 65 degree soil temperature at 4-inch depth for a minimum of three days and a favorable forecast. But, recent evidence indicates that this recommendation might need to be reevaluated.” 

Studies at the University of Georgia Tifton Campus were conducted by Dr. John Beasley, Dr. Tim Grey, and Beasley’s graduate student, Jason Arnold, under controlled conditions, to determine how soil temperature affects seed germination.

The tests covered a temperature range of 55 degrees to 75 degrees in 1 degree increments, and germination was recorded every 24 hours, starting at 48 hours after initiation. 

For the Georgia Greener variety, Sarver says, “The 65 degree soil temperature results were pretty striking. All the way out to 7 days, they only reached approximately 65 percent germination. At 3 days after initiation, germination was only at about 10 percent.  

“When moving to 70 degrees, at 7 days germination was 90 percent, and at 74 degrees, it was 95 percent. For Georgia 06G, results were similar. At a 65 degree temperature, germination was about 70 percent after 7 days, while at 70 to 74 degrees, germination was 90 percent to 95 percent, respectively.” 

While there may be some additional germination after the 7-day period, Sarver says, “The longer seed are in the ground, the longer they are exposed to soil borne pathogens, which may cause stand loss. An extended germination window also causes uneven plant emergence, which can lead to varying maturity within the field and harvest issues late in the season.” 

While the data are from only one year of an ongoing two-year study, Sarver suggests that the results are worthy of consideration by growers. 

“These results illustrate how sensitive peanut seed are to soil temperature. Based on what we know about the need to establish an adequate stand, it will benefit growers to err on the side of caution and wait until soil temperatures are closer to 70 degrees in order to insure rapid, uniform germination and emergence.”