A real Christmas tree can last anywhere from 3-5 weeks depending on various factors such as the type of tree, how well it is cared for, and the climate in which it is kept. Keeping a real Christmas tree hydrated, in a cool location, and protected from direct sunlight can extend its lifespan and help it last longer. Additionally, keeping the tree away from heat sources and other hazards can help prevent it from drying out or being damaged.