Our cross-pollinated sunflowers (F1 hybrids) did pretty well (the parents crossed on their own and reseeded themselves). One parent was a mammoth sunflower and the other was a smaller kind with more flowers. I don't know if they were the same species or just different varieties of the same species. The resultant ones were vigorous and had multiple flowers, but I think only one large one per plant (though it wasn't quite as large as the mammoth sunflower parent).

I don't know how well they would do if we kept letting them regrow (to F2+), though (especially without relocating them). I think if you have problems, it might help to introduce an heirloom variety every year or two to help it out (and cross-pollinate more). That's just a guess, though.

Part of the problem is probably that the dominant seeds that grow feral may not be the ones you want. I would suggest saving seeds from the plants and flowers that you grow that you like the most (and eating the others). Plus, try planting them in different locations every year instead of the same spot.

Also, you might want to consider doing something to sterilize the seeds in case of diseases. Maybe soak them in water with some hydrogen peroxide in it for a while. It shouldnâÂÂt hurt the seeds, and it should speed up germination, too.

This post was edited by Shule on Fri, Nov 28, 14 at 2:38