The lifespan of a Christmas tree depends on several factors, including the species, growing conditions, and whether it is kept indoors or outdoors. Some species of Christmas trees, such as the blue spruce or balsam fir, can live for several decades, while others, like the noble fir or Douglas fir, may only live for a few years. On average, indoor Christmas trees typically live for about 15 years, while outdoor trees may live for much longer. However, proper care and maintenance can help extend the lifespan of a Christmas tree, regardless of its species.