A live Christmas tree can last anywhere from 3 to 6 weeks indoors, depending on a variety of factors such as species, temperature, and humidity. The most important factor is keeping the tree watered regularly, as dehydration can cause the tree to dry out and die quickly. Keeping the tree away from heat sources such as fireplaces or radiators is also important, as this can cause the tree to lose moisture quickly. With proper care, a live Christmas tree can be enjoyed for several weeks and bring joy to the holiday season.