When to Harvest
Harvest the mature seeds once the back of the flower head is no longer green and begins to turn brown. The back of the flower feels dry once the seeds are ripe. Ripened seeds are usually glossy black with white stripes, though the exact coloration may differ depending on the variety. Cut the seed head from the flower, leaving an 8-inch length of stem attached.
Curing the Seeds
While the sunflower seeds are ripe at harvest, they need additional curing time to ensure they are dried thoroughly and to prevent rot. Place the seed heads upside down in a paper sack in a well-ventilated, dry room. Allow the seed heads to dry for a week or two, or until the seeds easily separate from the seed head. Finish harvesting the seeds by holding the seed head over a large bowl. Run your hand over the face of the flower, dislodging the seeds into the bowl.
Sunflower Seed Storage
Storage methods depend on the intended use for the seeds. Store the seeds immediately after curing in an airtight container if you plan to use them for bird feed. Roast or boil the seeds prior to storage if you harvested them for kitchen use. You can also store the dried seeds unroasted and roast them immediately before use. Use the sunflower seeds within three to six months to ensure best quality.