A cut Christmas tree can last anywhere from a week to a month, depending on various factors such as the species of tree, the freshness of the cut, and the storage and care of the tree. In order to maximize the life of a cut Christmas tree, it's important to properly care for it by providing it with adequate water and humidity, keeping it away from heat sources, and keeping it in a cool and well-ventilated area. Additionally, it's important to regularly check the water level in the tree stand and replenish it when necessary.