Posted: 17/08/2017 at 18:35
the seeds need to ripen to black and the pods go papery and open up before you pick them. Seeds must mature on the plant before they're dried off. Picked green they will never ripen.
It sounds a bit early, many agapanthus are still in flower.
If there are any still on the plant, let them ripen.
Dead-heading and seed collection don't go together.