To determine the freshness of a tree, observe whether it looks green and healthy,modern Christmas tree has a fragrant scent and has needles that are moist and flexible. If the needles appear dry or show browning, then that is a sign the tree will be a poor selection. If a large amount of green needles fall when branches of the tree are shaken, that's also a sign that the tree isn't the best one to buy to last for the entire season. The needles of the trees should break crisply when they are bent. If a tree needle is bent and doesn't break readily with pressure, it might mean that the tree isn't absorbing water and that will affect its longevity.