Christmas trees typically last about 4 to 6 weeks when displayed indoors. This time frame can vary depending on the freshness of the tree and the care it receives. It is important to water the tree regularly to maintain its moisture and prevent the needles from drying out. If the tree is not watered properly, it can become dry and brittle, causing it to shed needles and lose its freshness sooner. Additionally, keeping the tree away from heat sources such as fireplaces or heaters can also help prolong its lifespan.