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Sealed, they should do well for a long time. Just how long, only the manufacturer would know. Contact them and find out for sure. That being said, heres a few tests to decide for yourself. Lift/shake the EJ Bloom container. Does it feel bottom heavy? EJ has a tendency to precipitate a lot of solids. They recommend shaking the product well before use. I have had to shake a container for 5 minutes before it liquified completely, and that was after sitting for 1 month ... much less 4 years. If you shake it and it returns the solids to solution its a good sign. Next, pour some out and see if the solids have smoothed into the solution. Now smell it, it should smell like shit but not like rotten eggs (this is a sign of anaerobic contamination). If it smells ok, returns to a smooth fluid, and retains that milky tan color then the bloom should be fine. The Micro should smell "fresh", and be translucent with a green color. Shake this one too, but it should not contain solids like the bloom. If they pass these basic tests then you should be good to go. Maybe test it on a few plants before dosing the entire group? Well I hope that helps.