Sunflowers (Helianthus spp.) range from towering giants to small, bushy plants. It's the tall, large species and cultivars -- Helianthus annuus in particular -- that are grown for their seeds. Sunflower seeds are loosely divided into two groups: those called black oilseeds and those classified as confection seeds. The latter are yellow or white with black stripes.
Where They Come From
Black and yellow sunflower seeds come from cultivars grown primarily for the oil content of the seeds. Most sunflowers grown for their seeds are cultivars of Helianthus annuus, which is hardy in U.S. Department of Agriculture plant hardiness zones 2 through 11. Because it is killed by frost, Helianthus annuus is usually grown as an annual.
What They Look Like
Black sunflower seeds are smaller than their yellow or white-striped counterparts. They have solid black shells. Yellow sunflower seeds vary in how yellow they actually are -- some are very pale and more creamy-white than yellow. All have black stripes, however. The seeds can be harvested when the back of the flower head turns from green to yellow, but the heads aren't usually harvested for the seeds until they turn brown or black, according to the University of Kentucky Cooperative Extension Service.
Uses for Sunflower Seeds
Black sunflower seeds are pressed for their oil, which is processed into vegetable or sunflower seed oil. Black sunflower seeds are also used in cosmetics and margarine and are ground into meal and used in livestock feed. Confection sunflower seeds are sold as snack food or used in food products, with or without the hulls. Both types of seeds are also used in bird food mixes, and both types can be saved and used to plant new sunflowers.
Growing Your Own
Not all types of sunflowers produce edible seeds. If you want to grow your own for snacks, try "Mammoth Russian," which towers to 12 feet tall, according to the Washington State University Clark County Extension, and features large, striped seeds with thin hulls. Sunflowers in general grow best in full sunlight and in rich, well-draining soil. Shelter from the wind will help them stay upright.
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