About 2 weeks ago I posted on soil temperatures for planting corn. I am just now seeing some growers get in the field and start. We have a a few cold days forcasted in the next 10 days but the highs should even out the 2 inch soil temperature. So even though we are just beginning to plant corn, we need to be thinking about the upcoming peanut crop also. Here a few words from Dr. Scott Tubbs about soil temperature and weather forecast for planting peanuts.
Over the last couple of winters, you have heard Dr. Beasley and me refer to monitoring the 4-inch soil temperature as a guide for triggering planting decisions. There is data showing that peanut seed germination can drop fairly drastically once temperature dips below 68 F. It is suggested to allow the daily average soil temperature to stabilize above the 68 F mark for at least 3 consecutive days to buffer any drastic fluctuations. The soil temps can rise or fall very rapidly in the late winter/early spring as the daily max/min temperatures vary, and rain can likewise rapidly influence these temperatures.
For example – in Tifton, on Feb. 1 the daily high temp was 53 F and the 4-inch soil temp was 48 F. By Feb. 5 after 4 consecutive days of highs in the 70’s, the 4-inch soil temp had increased 14 degrees to about 62 F. But the very next day, a cold snap hit with a high of 47 F and low of 34 F, and the 4-inch soil temp dropped over 10 degrees in 1 day to 51 F.
This is why it is important to not only monitor the 4-inch soil temperature, but to also keep an eye on the weather forecast for the following 5-days or so. If there is a cold front predicted to hit before the seed can get planted and germinated, then there is the potential for seed to be shocked by decreasing temperatures, and end up with a poor plant stand.
After this week, the extended forecast for the week of March 8 is showing highs near or above 70 F for the entire week in Tifton. Thus, I expect soil temperatures to warm fairly quickly. If that trend continues, there is the chance that the 4-inch soil temperatures could be consistently above 68 F before the end of the month. But there is always a concern of an early to mid-April cold spell which could cause the soil temperatures to plummet once again.
I do not recommend planting earlier than around April 20, even then monitoring the combination of soil temperature and the 5-day forecast to give the peanut seed optimum germinating conditions so the full plant stand potential can be achieved. In the last 5 growing seasons, there was at least one instance each year where the 4-inch soil temperature dropped below 67 F after April 17. This was usually because of a cold front that brought cool rain and/or overnight lows in the upper 40’s.
Keep in mind that the Georgia Automated Environmental Monitoring Network has a Quick Reference for monitoring soil temperature at the 4-inch depth near most towns in South Georgia. At the website, just click on the “Peanut” link on the left side of the page, and you will get a drop-down menu that includes “Soil Temperature”, with an alphabetical listing of many locations that monitors the daily averages over the last 7 days, and the weekly average of those dates.