Only raw, uncooked seeds grow into plants. Cooking or roasting sunflower seed kills the embryo inside the seed, and may cause the seed to not grow.
During normal growth, water softens the seed shell, which allows the seed to sprout and take root. Roasting a sunflower seeds hardens the shell.
Plant raw, uncooked seed in soil after there is no chance of frost. Cover the seeds with about ¼ inch of soil, water well, and watch the plant grow through the summer and fall. Harvest seeds from the plant in the fall, when the seed shells have turned black with white stripes and the back of the bloom has dried up.