Fresh coconuts begin to spoil roughly two to three months after they are picked from the tree. Unless you know exactly when a coconut was harvested, determining its freshness is impossible.
Most of the coconuts sold in grocery stores come from Asia, although some are harvested in Hawaii. It is usually two months from the time the Asian coconuts are harvested to the time they reach the store shelves in the United States, so there is very little time to consume them before they begin to spoil. Once coconuts are cracked open, they last for roughly one week when stored in the refrigerator and six to eight months in the freezer.