Because it takes a lot of peanuts to make a jar of peanut butter, commercial peanuts are grown on hundreds of acres at a time. There’s also tremendous value in growing a few peanut plants of your own.
Originally from South America, where they were a prized food for thousands of years, peanuts are globally popular and commonly grown in southern latitudes.
Peanuts benefit from a raised bed, and the gardener may prefer this as well, since the plants grow so low to the ground. When planting directly in the ground, a simple furrow makes seeding a row an easy job.
Growing From Seed
Peanuts can be planted in the shell or hulled. The shelled seeds will germinate faster but will only be successful if the red “skin” is intact. Peanuts should be planted at a depth of 1.5 to 2.5 inches, in loose, moderately sandy soil, 18 inches apart, with 24-36 inches between rows. Make a shallow furrow in well-prepared soil, drop in the seeds, cover with soil and pack it down with a hoe, then water thoroughly.
Growing From a Starter
Peanuts are not generally grown from nursery starts, though you can plant them indoors if your growing season provides less than 130 frost-free days. Get them started about five to eight weeks before transplanting them outside once the soil is between 65 and 75 degrees F.
Like many legumes, peanuts benefit from being treated with nitrogen-fixing rhizobium bacteria, which you can purchase online. This can increase yields and help the plants add more vital nitrogen to your soil. After harvest, turn the spent plant material back into the soil to recover nutrients.
Peanut Plant Care
Peanuts require a little vigilance to help them flourish; this includes well-prepared soil, full sunlight, regular moisture, hilling, and possibly some amendments.
Peanuts need full sun, so be sure not to plant them in the shadow of larger plants or allow weeds to shade them. A study on the effects of drought and shade on peanut plants concluded that shade, especially during the stage when pods are being formed, significantly reduces yield.
Soil and Nutrients
Peanuts grow best in slightly sandy soil so the stems can easily plant the ovary. Though they would struggle to work the ovary into clay soil, peanuts can technically grow in any type of soil if you carefully prepare the seedbed so it is loose. Sandy soil also makes it easier to clean the peanuts after harvest.
Once the flower has been pollinated, its petals will dry and fall off, and the ovary will swell. At this time, hill some loose soil around the plant within reach of the “pegs,” as the fruiting stems are called, which will bend toward the soil and “plant” the fruit.
If the peanuts have not been treated with an inoculant, they may benefit from some amendments to adjust for any soil deficiencies or adjust pH levels to be slightly acidic. Fertigation—liquid feed via a drip irrigation system—can work very well.
While large-scale peanut farmers in the south use furrow irrigation, and growers in water-poor regions may use deficit irrigation (watering only at crucial development times), peanut plants may be the most productive and disease-resistant when watered regularly with drip irrigation, avoiding water stress. How much water the plants need will depend on evaporation rates, but organic mulch can help keep the soil from drying out.
Temperature and Humidity
Throughout its growing cycle, peanut plants need warmth and regular moisture—too dry or too wet will cause low yields and diseases. At harvest time, it is crucial for the soil to be moist but not soaked and heavy. Otherwise, some peanuts may break off and stay in the soil.
At the end of the growing season, when leaves start to turn yellow, the peanuts are ready for harvest. The National Gardening Association suggests slowly prying up the whole peanut plant with a pitchfork or shovel, then gently shaking off the loose soil. Then place the plant in a warm, shaded spot that offers good air circulation. Spread the peanuts out on a tarp to keep contaminants away while they dry.
Once you remove the peanuts from the stem, inspect carefully and discard any with discoloration or mold. Peanuts are susceptible to Aflatoxins, a disease that comes from the fungus Aspergillus. Controlling for pests, dressing the soil with calcium, and harvesting on time can reduce the incidence of Aspergillus.
Although commercial growers use specialized hybrid varietals, the small-scale grower can choose from four main types of peanut, selecting primarily based on the length of the growing season.
Virginia (120-130 days to mature): This varietal, which includes Jumbo peanuts, has the largest seeds and a gourmet taste and is usually roasted.
Runner (125-165 days): These provide high yields for commercial growers, the most uniform seed, and is preferred for peanut butter. Runners are also known as “beer nuts.”
Spanish (90-130 days): These smaller seeds have a higher oil content and robust flavor, and so they are usually roasted rather than boiled. Spanish peanuts mature early and are easy to pick.
Valencia (120-130 days): This peanut has a sweet flavor and bright red skin. Valencia peanuts mature fairly early, offer three or four kernels per pod, and are easy to pick because their pods form near the taproot.
How to Store and Preserve Peanuts
The Utah State University Extension recommends roasting before storage. The nuts can be placed whole on cookie sheets and cooked in the oven at 350 degrees F; roasting time will vary from 13 to 18 minutes. After roasting, peanuts can be stored in an airtight container and will last from six to 12 months in the fridge.