Fill an 8-inch plant pot with organic potting soil that has a pH of 6.0 to 6.8. Insert the navy bean seed into the soil at a depth of 1 to 1 1/2 inches, and water until the soil settles.
Set the pot in a warm window that gets full sun, which is eight hours daily. Keep the temperature between 60 and 79 degrees F at all times.
Water frequently enough to keep the soil moist to the touch, but not soaked. Water the soil directly instead of watering overhead, which can cause fungal growth on the leaves.
Apply a fish emulsion or other nitrogen-rich fertilizer to the potting soil if the leaves have a pale green color, which indicates a nitrogen deficiency. Follow the package directions for application.
Harvest the pods when the leaves are dry and brown. The pods should be dry, and the seeds should barely dent when you press them or bite down on them.