Add 6 inches of gravel to the bottom of the hole. This prevents the post from sitting in standing water, which is the primary cause of rot. 2. Set and Align the Post
Dig the hole to a depth equal to 1/3 to 1/2 of the above-ground height of the post. For a standard 6-foot fence, aim for at least 2 feet deep.
The hole should be three times the width of the post (e.g., 12 inches wide for a 4x4 post).