Answer: Wait until the seeds are fully ripe before harvesting them. The seedheads on your sunflowers are mature if they're bending downward and the back of the head is beginning to turn brown. Harvest by cutting the head plus two inches of stem off the plant and hang them upside down in a dry, well-ventilated place such as an attic or garage until fully dry. To extract the seeds, rub two heads together, or use a wire brush. Spread the seeds out until fully dry (test by crunching one between your teeth). Don't remove the hulls, but when fully dry, store the seeds in an airtight container. You can plant next spring after the soil has warmed.
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