My zinnias, marigolds, petunias, stock, snapdragons, periwinkles, touch me nots, and even more reseed twice a year. August they start growing from seed again. I also get reseeding in the Spring. Here are my reseeded zinnias.
Why do I have reseeding? My temperatures. There is not a frost line in the soil here. If it snows(usually ice pellets) the ground and sun melt it right away. If others from colder temps tell you they have not had zinnias reseed, go with that. You do not want to waste and freeze out good seed. The reseeding is true but true for a different area of the country.
Reseeding also has its downfalls you never know where they will pop up and it takes longer to get flowers. Either buying flats or starting your own seeds can give you flowers at least two months earlier than reseeds. I do all of the above because you can never have enough flowers! Many blessings for the success of your garden!
