Certain salvia produce many seeds like the ones I listed above. Just squeeze the pod and they pop out. Others only produce few seeds and you have to be diligent about looking for them. I look inside the pod to see if I see a black seed inside. Like I said --squeeze the pod and they usually pop out. Yvonne's salvia, guanajuato, blue angel, rose queen,greggii, are ones I have that you have to be looking for often . I've even found seeds from hot lips and black and blue but the offspring didn't turn out very good.
Now agastache seeds are another matter. They are very hard to collect for me and like mentioned above they are tiny. For those, I tap the flower part into a plate or similar thing. You only get a few seeds, so you have to keep doing that every few days.
