You can see if they are mature on the plant like LegalizeDaHurb says, they stick out with the familiar brown, and you can pinch them to check if they are hard. It takes 2-3 weeks for the seeds to mature. they fall right out when the bud is dried (a little help of course) I had two plants last grow go hermie very late in life, they produced some 60 seeds (between the two) and at least 20 from each plant are mature enough to germinate. Very glad my sativa dom seeded.
4x5 Reviewed by 4x5 on . harvesting seeds? I have looked about and don't see much on harvesting seeds, logic (mine anyways) would say to let the plant finish it's life cycle completely and allow seedss to mature. Anyone have some experience or knowledge to pass along it would be appreciated. Rating: 5