The peanut is typically thought of as a Southern U.S. crop, which is only half true. If your location provides 120 to 130 frost-free growing days, you may be able to grow your own peanut plants. That's about the same amount of time you would need for growing most melons and some types of corn. These plants produce fruit in an amazing manner. Each yellow bloom appears on a slender stalk, or peg, near the base of the plant. The peg elongates and grows downward, digging into the soil. The tip of the peg grows into a peanut. Growing a plant from a peanut will be a fun project for you to share with your kids. The seeds are actually raw peanuts and are often readily available from health food retailers and most grocery store produce departments.
Choose a very well-draining planting site in full sun three or four weeks after the last frost for your area has passed. It's important to wait until the soil has warmed to at least 65 degrees F and is no longer soggy.
Cultivate the soil well to a depth of about 12 inches. Bloom pegs can penetrate the soil to grow into peanuts only if the soil is loose. Apply a 2- to 4-inch layer of organic compost and work it into the top several inches of the soil. These plants are heavy feeders and love a rich, fertile growing environment. A pH range between 5.8 and 6.2 is best.
Plant raw peanuts whole in the shell 1 ½ to 3 inches deep and about 8 inches apart. Pack the soil lightly over them. Do not apply mulch at this time. Your peanut seedlings will sprout in about 10 to 15 days, and flowers will emerge about 30 to 40 days after that.
Water the planting site slowly and thoroughly. Keep the soil evenly moist, but not soggy or wet, until harvest. Peanut plants like moisture but won't tolerate wet feet.
Thin the peanut seedlings to 18 to 24 inches apart when they're about an inch tall. Hand weed the area conscientiously. Cultivate it shallowly as the seedlings grow to avoid damaging the roots.
Apply a 1- to 2-inch layer of organic mulch in early June. This will help retain moisture and go a long way toward discouraging weed growth.
Apply a 12- to 14-inch band of gypsum, or calcium sulfate, around your peanut plant when the blooms appear. The plant requires this material in order to form peanut kernels successfully. The typical application is 15 pounds per 1000 square feet, but may vary according to the particular product you're using. Follow the packaging instructions carefully.
Mound soil around the base of the peanut plant when it's about 12 inches tall. This will make it easier for the bloom pegs to reach it and grow their peanuts underground. When the pegs begin to poke into the soil, stop cultivating the plant's immediate vicinity to avoid damaging your developing peanuts.
Harvest your peanuts in the fall right after the first light frost damages or kills the plant's foliage. Dig up the plant and shake the soil from the roots and the peanuts. Pick the fruits from among the roots and set them in a warm room with good air circulation for several days until the shells feel rigid and dry.