Cut the individual sunflowers at the base of the stem for use in bouquets. Immediately place the cut flowers in water.
Cover each individual bloom loosely with a paper bag and tie the bag gently under the bloom. Leave the blooms covered for three to four days to allow the seeds to drop off. Remove the bags, being careful not to spill the seeds. Prepare the seeds to taste for eating.
Allow the plants to stay on their stems until they begin to wither. Birds will eat some of the flowers, while others will naturally drop their seeds into the soil. After the seeds have fallen, cut the old stems off at the base.
Cut the heads of the flowers off before they begin to lose seeds if you want to control future growth and plant placement. Discard the flowers.