Seed becomenon usable when they no longer germinate. We have seen open seeds germinate as well as some with minor cracks. They are very tough! Seeds remain viable for up to four years stored in a cool dark place but the germination ratio drops after about 2 years. If they are kept in the refridgerator we have seen seeds remain viable for up to six years. Seeds should be dark, plump and when cracked open be white in the middle with good structure. Hope this helped!
Check the picture. The small seed that is discoulored is not classified as healthy!

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