Fill the plant pot with organic potting soil. If you are transplanting a seedling, dig a hole as large and deep as the plant's container. Lower the seedling into the hole and firm the soil around the base of the basil. If you are planting the basil from seed, insert the seed into the soil at a depth that is twice the size of the seed.
Water the soil until it settles. Set the sweet basil plant in a sunny window that gets between 6 and 8 hours of direct sunlight. If you are keeping the pot outside, keep it in a spot that receives direct sunlight and is protected from high winds.
Apply a liquid, balanced fertilizer to the soil according to the package directions. Reapply the fertilizer twice a month.
Water frequently enough to keep the soil moist. If your pot has a base, fill the base with water and allow the soil to soak it upward.
Remove flower buds by pinching them off when they appear. Harvest the leaves by snipping them off a 1/4 inch above the next leaf node, using a sharp scissors.