To flock a Christmas tree, you will need a few supplies. First, you will need a Christmas tree. It can be a real tree or a fake tree, as long as it is a coniferous tree. Next, you will need flocking powder. This is a white, powdery substance that can be found at most craft stores or online. You will also need a spray bottle filled with water, and a paintbrush or sponge. Finally, you will need a safe space to work in, such as a garage or basement.