Navy beans and corn are a winning combination in a garden based on the Native American theory of the "Three Sisters," where beans and corn are grown together in for a mutually beneficial relationship. The Three Sisters also include squash. The theory is that since all beans can extract nitrogen from the air and store it in its roots, it provides nutrients for the corn, and the corn grows quickly on a strong, sturdy stalk so it provides vertical support for the vines of the bean plants.
Layer a 2-to-4 inch layer of compost onto garden soil that has been turned and is free of debris. Adding compost to the soil will help provide the necessary nutrients for the growing plants without having to add fertilizer.
Turn the compost into the soil using a shovel, mixing the organic matter of the compost into the garden soil to a depth of about 6 inches.
Form several mounds using a shovel to pile the dirt about 6 inches high and 12 inches in diameter. Space each mound so that the centers are approximately 16 inches apart.
Plant two corn seeds in the center of each mound, spaced 2 inches apart and 2 inches deep. Plant six navy bean seeds, keeping the corn seeds in the center and spaced in a circle, 6 inches from the corn seed but evenly apart from each other and 1 inch deep. To plant, push the seeds down into the ground using one finger and cover over the hole with soil.
Water each mound thoroughly for at least 30 seconds per mound if using a garden hose. If using a watering can, use 1/2 gallon per mound. Water the plants each morning for the first two weeks, then cut it back to suit the needs of the plants according to the climate of your area. Soil should range between moist and damp, but never dry out completely--check daily and water before it becomes dry.
Thin the corn plants to one single plant in each mound when they grow 4 inches tall. Pull out the smallest of the two plants that sprouts. Thin the navy beans to three plants each mound.