A. If stored in its original container, Dip ‘N Grow is best used within 3 years of manufacture. Limiting exposure to sunlight and heat will help prolong the shelf life. Dip’N Grow has a tendency to darken over time without losing its effectiveness. Once diluted with water, Dip ‘N Grow should be used within a 10-12 hour period. Two things need to be done to make sure there is no contamination of the concentrate. One: never return the mixture to the concentrate. Two: never dip the cuttings in the original concentrate bottle.