With enough sun, though, sunflowers can do multiple duty in the garden: attracting birds and bees; feeding birds; providing snacks, bouquets, and beauty; or offering support for other plants, like tomatoes, as a kind of green, living stake. The seeds are also a natural herbicide, as anyone who has tried to grow grass under a bird feeder will know. And they work similarly to cover crops, returning macronutrients to the soil. Birds may become an enemy when seed heads appear—especially if a gardener's goal is harvesting the seeds for snacks. Sunflower seeds are an energy-dense food for seed-eaters, winged and otherwise. In some varieties, about 40 percent of the weight is oil, which is very high in vitamin E. Sunflower seeds are also rich in thiamine (vitamin B1), a number of minerals, and phytosterols, chemicals that have been linked to lower cholesterol.
But, warns Dimitrov, birds also love the tender shoots that start appearing less than 2 weeks after planting. "Those young sprouts are very tasty," he says. "Birds usually go after seedlings at the two to four leaves stage, but after that they leave them alone. The plants are fast growing, so that helps. The only thing you can do is sow extra seed. Hanging old CDs is an innovative way to scare the birds, or have fun with the kids by creating scarecrows." Protect the seed from the birds by covering the heads with burlap when the disks start to fill in, advises Dimitrov.
Cut sunflowers for bouquets from the time the bud appears. The first sign that seed is ripe for harvesting is when sunflowers stop being sun worshippers. Their heads droop, the inner flowers easily rub off, and the outer petals have clearly called it a day. The back of the seed head should be a lemony yellow color. Check a few seeds to make sure they contain a kernel. If it looks like a go, remove the entire head and place it in a bag or cheesecloth and hang it in a cool, dry, dark place to dry further. After about 2 weeks, the seed should be ready for roasting—or for the bird feeder. For human snacks, place seeds in a shallow pan and roast at 300°F for 30 to 40 minutes.