Such a basic question for so many of you (I am a perennial gardener and know not of growing from seed):

With hopes of being able to harvest seed for next year's garden, I recently gathered a just-gone-by dark red sunflower head. Will these nascent seeds develop and be able to be harvested for next year, or does one have to wait to cull the flower heads and their seeds AFTER they have died and show no green ? Thanks much for your help

Mindy