I know that some producers have had to replant peanuts in June, this article is going to focus on April and May planted peanuts. According to Wes Porter, UGA Irrigation Specialist, peanuts (throughout the month of June) are requiring 1 to 1.75 inches per week. If you missed that first window and have just finished up planting your peanuts in the month of May then you are still at a low water use stage.
You are ranging somewhere between 0.2 and 0.8 inches required per week. Overwatering can hurt just as much as under-watering. Focus on keeping a record of local rainfall events and especially your irrigation applications. Just blindly irrigating a set number of times per week throughout the season will not aid you in properly meeting your requirements for the crop. Irrigating blindly will also not help in maximizing yield potential nor profit potential.
Remember this requirement is IRRIGATION and RAINFALL! Irrigation may not even be required in the first few weeks! Good record keeping and a sound irrigation scheduling strategy can aid significantly in increasing profitability in multiple ways, including reductions in irrigation applications, correlating to reductions in energy requirements, and potentially increases in yield. Below is a graph that illistrates the weekly water use for peanuts and highlights the water requirements for April and May planted peanuts.
(Source – http://www.farms.com/news/peanut-watering-requirements-109195.aspx)