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 warmer climates. These annuals are normally planted from seeds (shelled peanuts) in the spring after the last frost and harvested in the early fall. They require as much as 150 days to produce edible peanuts, but there are early maturing varieties that require less than 100 frost-free days.
|Botanical Name||Arachis hypogaea|
|Common Name||Peanuts, goobers|
|Mature Size||1–2 feet tall, 3 feet 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 zones|
|Native Area||South America|
How to Plant Peanuts
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. Shelling ordinary raw, uncooked peanuts gives you the seeds necessary to grow peanuts. Raw grocery peanuts can work for this, though it's better to buy your seed peanuts from a garden center.
Sow seeds directly outdoors after the last frost. Remove the shells before sowing but be careful not to damage the tender skin on the seeds. Plant the seeds 1 to 2 inches deep, 4 to 6 inches apart. Leave 3 feet between the rows. Keep the soil moist to ensure germination. Seeds will germinate in ten to 15 days. Thin the seedlings when they are about 2 inches tall, to a spacing of 8 to 12 inches. As the plants grow, "hill" them by heaping additional soil around the base of the stem.
Keeping the area around the plants weed-free and loose is very important because once the plant has flowered and has been pollinated, it will start sending pegs into the soil. Adding a couple of inches of mulch helps with weed control.
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 ten 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.
Temperature and Humidity
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.
- Valencia peanuts are the quickest to mature in 90 to 110 days. It is therefore often the variety of choice for home gardeners. They have three to five relatively small kernels per pod, with pretty red seed coats.
- Spanish peanuts take 90 to 120 days to mature. The peanuts are mainly used for candy and as roasted peanuts.
- Virginia peanuts and runner peanuts both require about 130 to 150 days to mature. This variety produces a high yield of large pods with excellent flavor. As their name indicates, runner peanuts need more space, about 3 1/2 feet per plant. The fruit is small, with two kernels per pod. They have excellent flavor and are most commonly used for peanut butter. Both Virginia and runner peanuts are intolerant of cool temperatures and drought.
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. Dig or pull the entire plant from the ground and gently shake it to remove excess soil. Hang the plants with the peanuts attached in a dry, warm location with good air circulation. Leave them to cure for about one week.
After curing, shake the soil from the pods. Remove the peanuts from the vines and continue to air-dry the peanuts for another week or two.
Common Pests and Diseases
Peanuts can be affected by a wide range of pests and diseases. Leaf-feeding insects may include armyworms and caterpillars. Common diseases are leaf spot, rust, blight, and viral diseases. Some diseases can be avoided or minimized by choosing less susceptible varieties.
As with all pests and diseases, before any type of treatment, make sure to properly identify what is harming the plants by seeking help from your local University Extension office. They will also suggest the best remedies for the ailments.