If you use essential oils for laundry as part of the recipe, you can expect the powder to last for anywhere between 6-12 months. When you make your own laundry detergent it should have a long shelf life because the essential oils, baking soda and borax do not tend to expire quickly. Storage is key, so you should always keep the detergent in a tightly sealed container in a cool, dry dark area away from direct sunlight and heat sources.