I generally recommend watering a Christmas tree every day or every other day to keep it fresh and healthy. Watering it regularly helps keep the tree hydrated and prevents it from drying out and becoming brittle. However, the exact amount of water you should give your Christmas tree depends on several factors, such as the tree species, size, and environmental conditions. If you notice the needles on the tree beginning to wilt or turn brown, it may be a sign that the tree is not getting enough water and needs more frequent watering.