How to Grow Peanuts
By Nadia Hassani
Ever-popular peanuts are actually not nuts at all, but the underground seeds of a tropical legume plant related to peas and beans. And peanuts have a truly unique growing habit. While the yellow flowers bloom above ground in traditional fashion, the fruit and their seeds develop at the end of live shoots called "pegs," which grow down into the ground. The peanut clusters are the fruit that forms at the ends of these pegs.
Peanuts have a long growing season and are most often grown in warmer climates, but you can try your hand at growing them indoors. These annuals are normally planted from seeds in the spring after the last frost and harvested in the early fall. They require between 100 and 150 days to produce edible peanuts.
Botanical Name | Arachis hypogaea |
Common Name | Peanuts, goobers |
Plant Types | Annual |
Mature Size | 1–2 ft. tall, 3 ft. wide |
Sun Exposure | Full sun |
Soil Type | Sandy loam |
Soil pH | 6.0–6.5 (slightly acidic) |
Hardiness Zone | 2–11 (USDA); but most productive in warmer zones 8-11 |
Native Area | South America |
If you live in an area where summers are long and warm with at least 120 to 150 frost-free days, you are in the right location to grow peanuts.
Once seeds go in the ground, keeping the area around the peanut plants weed-free and loose is very important to produce healthy pegs. After the plant has flowered and has been pollinated, it will start sending pegs into the soil. Adding a couple of inches of mulch when the plants grow to about a foot tall helps with weed control and keeps the soil soft enough for pegs to penetrate.
After the pegs have entered the soil, do not disturb them. You might see lots of flowers on the plants but only 15 percent of them will actually send a peg into the soil and grow peanuts.
Peanuts need full sun for at least eight hours per day.
Peanuts grow best in loose, well-drained, sandy loam. Avoid poorly drained and hard clay soil. Do not plant peanuts in the same space where you have grown other legumes (beans or peas) in previous years.
Peanuts need about 1 inch of rain or irrigation per week during the growing season. Watering is most critical immediately after planting, to ensure germination and establishment of the seedlings, then again 60 to 110 days after planting when the pegs have entered the soil and are filling with peanut clusters. Stop watering the plants 10 days to two weeks before harvesting.
When watering, avoid wetting the leaves and use drip irrigation if possible. The soil should be moist but not saturated.
The ideal growing temperature for peanuts is between 86 and 93 degrees Fahrenheit. Higher temperatures may lead to flower damage.
Slightly humid conditions are good while the plants grow but a period of dry weather is needed before the harvest.
Peanuts need calcium in the upper 6 inches of the soil where the pods grow. Amendment with bone meal or another source of calcium at the time of planting can help with this.
Peanuts are a legume that fixes its own nitrogen in the soil if rhizobium bacteria are present. Therefore peanuts do not need additional nitrogen fertilizer. However, if you plant them in a location where peanuts have never been grown before, it might be a good idea to add a peanut inoculant to the soil at the time of planting which stimulates the roots to grow the nodules that fix nitrogen in the soil.
Note that peanuts are extremely susceptible to fertilizer burn, so if you do feed, do so before seeding and make sure to thoroughly work any fertilizer into the soil.
Several signs will tell you that peanuts are ready to be harvested in late summer or early fall. The most obvious is yellowed foliage, but you should also pull a couple of pods from the ground and inspect them carefully. Ready-to-harvest pods have the typical veined surface, the seed coats are colored, and most of the pods have a darkened inside surface. When you harvest the peanuts, the soil must be dry.
Peanuts can be affected by a wide range of pests and diseases, especially hungry squirrels, mice, and chipmunks (secured mesh row covers can help here). Leaf-feeding insects may include armyworms and caterpillars. Common diseases are leaf spot, rust, blight, and viral diseases. To help identify what is harming the plants, seek assistance from your local university extension office. They will also suggest the best remedies for the ailments.