They should be fine. I feed the birds every day out in the street - no feeder competition - with a good quality seed mix, and I always end up with a little crop of sunflowers each year on my lawn. I then save a few of the seeds of each plant. The birds must be happy with my decision; all I have to do is shake the seeds in their metal container and they start twittering and flying onto the street, waiting for breakfast. I think I had about 80 the other day, right after a big snow. They were hungry!

Keep in mind that each sunflower you grow from seed mixes may look completely different than what you'd expect. Mine end up about 4-5' high with different flowering patters: one may have a single head, one may have 10. So if you want a particular look or height, you may be wise to spend the money and buy a seed packet of sunflowers that mature consistently. Me, I like a surprise! Have fun.