A cut Christmas tree can last anywhere from a few weeks to a month, depending on several factors. The key factor is how you care for the tree. To keep your tree fresh and healthy, make sure to cut the trunk at an angle, place it in water, and keep it away from direct sunlight or heat sources. Additionally, you can add a tree preservative to the water to help the tree absorb water better. With proper care, your cut tree should last you through the holiday season and beyond.