Jay Capasso (UF/IFAS NFREC – Suwannee Valley) and Wes Porter (UGA Crop and Soil Sciences Department)
Peanut harvest season has begun in North Florida which raises the question: when should you terminate irrigation in peanuts? Unlike corn, peanuts are an indeterminate crop, meaning plants will continue flowering and setting pods over an extended period instead of reaching maturity at the same time. Due to this growth habit, peanuts do not have a clear physiological irrigation termination point.
Irrigation in peanuts is generally beneficial until most pods have filled and the crop is approaching maturity. Keeping soils moist late in the season can reduce stress, but too much moisture may raise disease pressure. Dry conditions late in the season can cause pods to loosen and break away from their stems. In peanuts grown for seed, dry conditions can reduce seed quality if pods dry out excessively before harvest. In addition, soil type and weather conditions are important considerations, as Florida’s sandy soils dry out quickly and depending on rainfall, may require irrigation close to harvest. As of September 15, 2025, conditions in the Suwannee Valley are currently dry with little to no rain in recent weeks and no rain in the forecast. Note that conditions could change but growers should avoid shorting the crop under current conditions, as irrigation may be needed up until very close to digging.
When scheduling irrigation late in the season, it is important to consider peanut water use requirements. As shown in Image 1, water demand begins to decline around 80 days after planting. Most runner-type peanuts reach maturity around 140 days or 2500 Growing Degree Days (GDD’s), with the exception of longer-season varieties such as 12Y, which requires closer to 160 days. It is recommended to start conducting maturity checks around 120 days or 2100 GDD’s after planting.
Once you know the estimated digging date for your field, ideally based on pod-blasting methods, consider current soil moisture, the timing of your last irrigation or rainfall, the short-term weather forecast, and crop water use. Near harvest, peanuts use about 0.04 inches of water per day. In North Florida’s sandy soils, the water-holding capacity is only about 0.7 inches per foot (generally for row crops we estimate that 50% of soil water holding capacity is plant available, thus, the crop can only access about 0.35 inches per foot in most of our sandy soils), making irrigation necessary even during growth stages with lower water demand.
General late season irrigation guidelines include:
- If digging is soon and moisture is adequate, terminate irrigation.
- If digging is soon but fields are dry and no rain is expected, apply one more irrigation; if reliable rain is forecasted, hold off.
- If digging is still weeks away and fields are drying out with no rain predicted, irrigate.
- If moisture is adequate and rainfall is uncertain, monitor conditions and decide closer to digging. And, if rain comes, terminate irrigation.
Excessively dry soils at digging can increase the wear on peanut digging equipment. The abrasive nature of soil particles, especially sand, acts like sandpaper on peanut digging blades, causing them to dull and wear out faster.
It is common practice (although not recommended) to terminate irrigation once peanut digging begins. On larger farms, where peanut digging can take 30 days or more, the crop might experience water stress during this period (especially later planted fields). Although peanut water demand is reduced later in the season, the current dry conditions, which are not uncommon in September and October, can still make irrigation necessary.
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