Although Grow Company, Inc.'s High Mineral Yeasts, Re-Natured® vitamins, Biogrown®, and Biogurt™ nutrients do not require refrigeration, it is best stored under 50-55ºF. It is important to allow them to reach room temperature just prior to use. Packaging containers need to be kept tightly closed once they have been opened. If these products are kept at 50-55ºF, 30-35% relative humidity, and tightly sealed, they are stable for three years from the date of manufacturing.