Free: Contests & Raffles.
I prefer 7"+ treated round posts for corners and gates. I have been replacing old cedar and oak RXR ties with them. All of my RXR ties have lasted less than 20 years while my treated are still good, except those that were set in concrete. Those set in concrete have rotted at the base. Most of my old RXR ties are 10' with 5' in the ground. If your type of ground allows always get at least 8' posts and bury them as deep as you can without cutting them off. Also, it is best to set posts when the ground is damp to get the dirt to pack tight.