Whether you grow giant sunflowers or standard sunflowers, as the summer fades the sunflower seeds will swell within the flower heads. Some gardeners enjoy leaving the sunflower seeds for the birds, but perhaps you have other plans for the seeds. Harvest the seeds for roasting or harvest them to plant next summer. If you plan to harvest your sunflower seeds, you must protect them from the birds first, and then dry the sunflower seeds from the plant.
Watch the sunflower heads for indications that the seeds are ripening. When the sunflower petals wither and fall from the heads and when the seeds become large in the center of the sunflower heads, they are ripening.
Place a mesh bag over each sunflower head to keep birds away from the seeds. Staple the opening of the mesh bag tightly around the stem of the sunflower just under the sunflower head.
Cut the sunflower heads from the plants when the outer seed coating is hard.
Place one sunflower head into each brown paper bag and roll the bags up loosely. This will help the sunflower seeds to dry more quickly on the sunflower heads. Place the paper bags in a warm dry location.
Check the progress of the drying once or twice per week. Run your hand briskly over the seeds on the sunflower heads. If the seeds loosen easily and fall off the heads, they are sufficiently dry. If they are not loose, return the sunflower heads to the brown paper bags and continue to dry them for two or three more days.
Remove the sunflower heads from the paper bags when the seeds are dry. Separate the sunflower seeds from the heads, if they do not fall out on their own, and place them in an airtight container for storage.