There are telltale signs to watch for with sunflowers that indicate maturity. It’s best to watch and wait before cutting them down and collecting the seed.
Signs of maturity of a sunflower head includes a nodding head, central disc florets which easily fall off, yellowing at the back of the head, and possibly some loose seeds.
Remove the central disc flowers from the face of the sunflower. Cut the stem approximately six inches below the sunflower head, and remove all of the leaves.
After drying the heads, it's time to harvest the seeds. This is relatively easy as the seeds become looser. Work the sunflower seeds with your fingers to loosen them up.
As soon as you get a few seeds loosened and out of the head, it will be easier to work the rest out. Keep wiggling them with your fingers until they drop out.
After harvesting the sunflower seeds, sort through them and remove any empty seed and chaff.Spread the seeds out on a clean dry pan or plate to allow them to dry.