Once a Christmas tree is cut, it begins to lose moisture and will typically only last a few weeks before it starts to dry out. The length of time it lasts depends on several factors, including how well it's cared for and how much water it receives. A well-watered tree that is kept in a cool environment can last up to a month or more, while a poorly-watered tree in a warm room might only last a few days. If you want your tree to last as long as possible, be sure to water it daily and keep it away from any heat sources.