Peanut

Wait until soil at the 4-inch depth averages at least 65 F for three straight days with warm weather in the forecast, then sow shelled seed 1 to 1.5 inches deep, 10 to 12 inches apart, in rows 36 inches apart. Warmer is better: UGA measured 70 percent germination after a week at 65 F versus 90 percent at 70 F, and prefers to wait for 68 F. Peanuts are tender and resent transplanting, so seed them in place. Count your frost-free days first: the crop needs a minimum of 120 of them, so short-season gardeners should choose a Spanish or Valencia type rather than a Virginia or Runner. Peanut is a warm-season annual from South America with no frost tolerance, and seed sown into cold soil emerges erratically or rots, which invites seedling disease and thrips damage. The whole crop has to flower, peg, and fill pods before the first freeze, so the length of your frost-free window, not hardiness zone, decides which type can finish. Arkansas Extension gives the depth, spacing, and the 120 frost-free day minimum; the 65 F at 4 inches threshold is the standard extension planting rule rather than a figure from that fact sheet.

Dust the seed with a peanut-type Rhizobium inoculant at planting, especially in ground that has never grown peanuts. Skip nitrogen fertilizer. Aim for a soil pH of 5.8 to 6.2, and avoid heavy spring potassium near the row. Peanuts fix their own nitrogen once Rhizobium bacteria nodulate the roots, so added nitrogen just buys vine at the expense of pods, and the bacteria are often absent from soil with no peanut history. High potassium in the pegging zone competes directly with calcium uptake, which is the nutrient the pods actually need.

Once flowering starts, hill loose soil toward the plants and lay 1 to 2 inches of light organic mulch around them. Pull weeds in the row by hand from here on. Do not cultivate or disturb the soil after the pegs have buried themselves. After a flower is pollinated its stalk elongates into a peg that drives down into the soil, and the pod forms at the tip. A peg will push through loose soil on its own but cannot penetrate a hard baked crust, and a hoe run through the row after pegging simply severs the crop you are growing. Only about 15 percent of flowers ever set a pod, so protecting the ones that peg matters.

As the first yellow flowers open, work agricultural gypsum into the top few inches of soil along the row. Virginia types, with their big pods, need roughly twice the calcium of Spanish and Runner types. If a pegging-zone soil test taken 3 inches deep beside the row already shows 500 lb per acre of calcium and a calcium-to-potassium ratio of 3:1 or better, you can skip it. The developing pod cannot pull calcium up from the roots; it absorbs it directly out of the soil water surrounding it, and about 92 percent of that uptake happens within 20 to 80 days after the peg enters the ground. Miss the window and you get empty shells called pops, pod rot, and seed that will not germinate next year.

Where summers are warm and rainy, begin chlorothalonil about 30 days after planting and no later than 45 days, repeating every 14 days. Look for pencil-width brown spots with a yellow halo on upper leaf surfaces, or darker black spots with feathery margins and heavy sporulation underneath. In dry-summer gardens, scout instead and spray only if lesions appear. Stop spraying 14 days before you plan to dig; a last application around 120 days after planting usually carries control through to harvest. Early leaf spot (Passalora arachidicola) and late leaf spot (Nothopassalora personata) infect during prolonged leaf wetness between 65 and 90 F, and lesions do not surface for 10 to 14 days after infection, so by the time you see spots the next cycle is already underway. Unchecked, they defoliate the plant and the pods stop filling.

From roughly 55 days after planting until about 95 to 100 days, keep soil moisture up: peak use can reach 0.3 inches per day, more than 1.5 inches per week. Water before the plants look stressed rather than after. On sandy soil, reserves can run out in about three days at peak demand. Blooming, pegging, and pod development are when the crop's water use peaks, and this is also when soil water carries calcium to the pods. Dry soil bakes the surface so pegs cannot enter, and once drought symptoms are visible the yield loss is already irreversible. Steady moisture also cools the soil, which suppresses the Aspergillus flavus and A. parasiticus that make aflatoxin under hot, droughty conditions.

For boiling peanuts, dig green at 90 to 110 days after planting. For roasting, wait 130 to 150 days and check maturity by scraping or blasting the outer hull off a sample of pods: dig when 65 to 70 percent show dark hull color inside. The foliage yellowing is your cue to start checking. Dig when the soil is dry enough to shake off the plants, and lift the whole plant rather than pulling pods. Pods on one plant mature over a long span, and the hull's inner color is the only reliable read on the crop as a whole. Dig too early and the kernels are immature and flat; wait too long and the pegs rot through so the oldest, best pods stay behind in the ground. Late-season rain on an over-mature crop also drives fungal growth and aflatoxin.

Following Arkansas Extension's curing sequence: stack or hang the pulled plants upside down in an open shelter or a warm, dry shed or garage with free air movement for about a week. Then shake off the remaining soil, pull the pods from the vines, and air-dry them another one to two weeks. Do not pile wet pods in a closed container or bag. The target is about 7 percent moisture in the pod; once dry, pods keep for close to a year at around 70 percent relative humidity and 77 to 81 F. Freshly dug pods are wet and must be dried down to about 7 percent moisture. Aspergillus flavus and A. parasiticus grow and produce aflatoxin once pod moisture sits above 8 percent, with optimal growth at ambient temperatures between 82 and 98 F and high relative humidity above 85 percent, which is exactly the microclimate inside a heap of undried peanuts.