The time it takes for Christmas trees to grow varies depending on the species and the climate conditions where they are grown. In general, it takes around 5-10 years for a Christmas tree to reach a size that is suitable for harvest and sale. However, some species can grow faster than others, and in optimal growing conditions, it is possible to harvest a tree in as little as 3-4 years. The growth rate also depends on how the trees are grown and cared for.