The word "sunflower" applies to about 70 species of Helianthus, and nearly all of them are native to various locations in North America. All varieties produce a central cluster of seeds. Sunflowers require a lot of space to grow, and some varieties can exceed 10 feet in height. You can even plant the black-oil sunflower seed you purchased to feed the birds. Plant the seeds a few inches apart, but expect to thin them to about a foot apart as the plants grow. They'll need lots of water and sunshine, and perhaps the support of a stake and tie-back as they mature. Read the description of the plant and flower head size on seed packets before you buy. From mid-May to early June is a great time to plant these fast-growing beauties that will mature into nature's own bird feeder.