Apply a 3"-4" layer of mulch to conserve moisture and keep down weeds. Sunflowers are drought-resistant, but they'll grow better if you water regurlarly from the time the flowers begin to develop until they're mature.
Sunflowers are remarkably trouble-free. Rotate crop if leaf mottle, a soil fungus that produces dead areas along leaf veins, becomes a problem. An early autumn may interfere with pollination and cause the plant to form empty seeds; plant earlier the next year. To protect seeds from birds, cover flowers with mesh bags, cheesecloth, old pantyhose, or perforated plastic bags.
Harvest as soon as seeds start to turn brown or the backs of the seed heads turn yellow. The heads usually droop at this time. Cut them along with 2' of stem and hand upside down in a dry, well-ventilated place, such as a garage or attic, until fully dry; store in plastic bags for birds and animal food. To eat, soak overnight in water (or strong salt water, if a salty flavor is desired), drain, spread on a shallow baking sheet, and roast for 3 hours at 200°F or until crisp.