Measure the height of the planter tower, then measure the PVC pipe to that same height. Mark around the pipe at that measurement using the marker.
Cut the PVC pipe on the mark using a hacksaw or PVC cutter.
Drill a hole 1-inch from the bottom of the pipe using the drill. Turn the pipe slightly to the left and drill a second hole 1/2-inch from the bottom of the pipe. Keep turning the pipe and drilling holes, alternating between the two measurements. Stop when you make one complete turn around the pipe.
Slip the sock over the bottom of the pipe where you drilled the holes and secure it with the rubber bands.
Fill the planter tower with 1-inch of potting soil.
Place the pipe sock-side-down into the planter so the bottom sits on the top of the soil and it is at least 1-inch from the side of the planter. The sock keeps the dirt from clogging up the holes, and water flows through the sock.
Fill the planter with soil using your hands and the spade until the soil is 1-inch from the top of the planter. Pack the soil down lightly to help hold the tube in place.
Pour water into the tube until it is at least half full. Dip the dowel into the tube and pull it back out. Mark the height of the water on the dowel using the marker. Check the height of the water regularly to determine if the planter needs water.