I have leftover Miracid and Miracle-Gro from last year. Is it good this year?
The Gardener’s Answer
The answer to your question depends on the form of your plant food. Powder-based fertilizers should last for several years if properly stored in a dry space at room temperature. Liquid fertilizers, on the other hand, have a shorter shelf life and should be used within two years of purchase. Ideally, they are stored at room temperature, between 60 and 70 degrees. If liquid fertilizers are subjected to drastic temperature changes, especially freezing temperatures, this can cause separation, changing the chemical composition of the product.
Plant food comes in a variety of different sizes in granular, water soluble, and liquid form. You usually get a better price if you purchase a larger quantity, but if it is not going to be used within a season it really is best to buy the smaller size and start fresh each growing season. That way there is no guessing about whether your plant food is still viable.