John Savage expounded:

I'd like to know how you manage it! I grew masses of snapdragons from
supermarket seedlings, and then harvested thousands of seeds when they
had dried. Both that summer and the next I planted lots, anticipating
a self-perpetuating mass of blooms til eternity: very dark seeds for
the red flowers, and lighter seeds from showey yellow blooms. Not one
seedling came up!! I tried a few different conditions, still nothing.

Where are you located?
--
Ann, gardening in Zone 6a
South of Boston, Massachusetts
e-mail address is not checked
******************************