Saving seeds - old plants, self-propagation

[Anonymous]

I still have some dead plants from last year in my gardens - such as marigolds, daisies, cone flowers, and some others. I was thinking that their seeds could be used to plant more flowers this year, and that if I left them, they would just propagate on their own. Is there any truth to my thinking? Maybe I should gather seeds in the fall instead? Or maybe I should plow the plants under? I suppose whatever seeds would have frozen. Is there anything I should do now, such as plowing under the old flower heads?

[Anonymous]

You might get one or two plants "naturally" this way but most of the seeds were eaten long ago by birds and bugs.

Seeds are o.k. with freezing winters if the plants are suited for your zone. I have never had a cone flower seed itself here - the birds get ALL the seeds. That's why i plant them!