You use your "shorter" posts when setting them under a full moon. Posts set under a full moon will continue to grow to extreme heights depending on the ph of the soil, moisture level and if you fertilize before sunrise on the third day. That is how telephone poles are made. Jogeephus plants the pole sections on his farm when they are about 2' long (cuts up used poles into 2' sections until he has enough to plant a field) and sets them in rows about 8 feet apart so he can bushhog around em. He limes, waters, fertilizes and then sets back and awaits the fall harvest of beautiful telephone poles. I am sure there is more to it than that so maybe Jo can weigh in on the details without giving away any of his hoarded trade secrets.