I put 2 in each and did not cut them I think they were 8 ft and I drove the excess into the ground with a sledge. I also drilled my mounting hole and put in the bolts prior to filling the pvc. Looking back I probably would have spent the extra 5 bucks or so and bought black pvc but hindsight is always 20/20! I did dig out a hole about 12 inches deep and 12 inches in diameter prior to using a post hole digger to put the pvc about 2 ft total in the ground as a small footer.
Bob