Planting Preparation for Peanuts
Getting the soil prepared for planting is key to a healthy and bountiful peanut harvest.
Peanuts prefer a well-drained soil with a sandy or sandy-clay subsoil. The nut-forming pegs penetrate sandy soils easily, but have trouble with clay soils. At harvesttime, sandy soils won't cling to the nuts, nor will pods be lost because of heavy soil. However, you can grow peanuts in any type of soil if you carefully prepare the seedbed to the point that it's loose and friable.
To determine the type of soil in your garden as well as the pH level and the needed nutrients, it's best to test your soil. For information about testing, contact your local Extension Service.
As with all legumes, you can often increase your peanut yield by inoculating the seeds at planting time with a nitrogen-fixing bacteria.
Nitrogen is one of the three most important nutrients in plant growth, and it's vital that your soil contains enough to support your plants' needs. You can improve the nitrogen content by growing legumes because of the unique ability of the symbiotic bacteria living in the nodules of legume roots to draw elemental nitrogen from soil air and "fix" it into a usable form.
To make sure your plants "fix" the most nitrogen possible, inoculate the seeds with the nitrogen-fixing bacteria just before you plant. Inoculating seeds has proved to increase the number of nitrogen nodules and has a positive effect on yield as well. Inoculant, usually in the form of a wettable powder, comes in small packages and can be purchased in seed stores and through seed catalogs.
It's easy to inoculate seeds. Simply place the seeds in a pan, add enough water to moisten them, and add a small amount of inoculant to the water. Stir the seeds with a stick until they have a little powder on their seed coats and then plant them immediately.
For best results when growing peanuts, your soil should be slightly acid with a pH of 5.9 to 6.3. If the pH is below 5.9, broadcast lime over the row and work it into the top three to four inches of soil where the peanut pods will develop. Although you can apply lime in the spring, it's more effective when added in the fall because it takes awhile for the lime to work. To raise the pH level one full unit on the scale, use about five pounds of ground limestone per 100 square feet.
Gypsum, which contains a lot of calcium, is often used on peanut plants in the West, where the soil tends to be more alkaline. When the plants start to bloom, sprinkle the rows with about six pounds of gypsum per 100 square feet. This also helps to satisfy the plants' need for calcium. If the pegs don't receive enough calcium, you may be left with unfilled pods and few peanuts.
In addition to supplying the soil with organic matter, broadcast three to four pounds of 5-10-10 fertilizer over each 100 square feet and work it into the top two to three inches of soil shortly before planting. Peanut seeds and young plants are sensitive to fertilizer burn, so don't apply fertilizer directly to rows where you'll be planting peanuts.
As a member of the legume family, peanuts have their own supply of nitrogen. For this reason, use 5-10-10 fertilizer, which contains less nitrogen than other commercial fertilizers. If the peanut seeds have been inoculated with nitrogen-fixing bacteria, they'll be able to draw elemental nitrogen from the soil air, change it into a usable form and store it in the nodules of the plant roots.
This article is a part of our Vegetable Gardening Guide for Peas and Peanuts / Getting Started.