Digging fence post holes is easiest with a power earth auger. A digging bar works well for loosening dirt from each side. When you are digging post holes, the hole should be half the post height above the ground. For instance, if your fence posts are 6 feet tall, then your holes should be about 3 feet deep. If the posts are 8 feet high, then your holes should be 4 feet deep. It’s best to use a post hole digger or a gas powered auger drill for this. Once your post holes are dug, set the posts on a 6 inch base of half inch crushed stone to ensure proper water drainage. Brace the post to keep it straight by using two stakes and some scrap lumber. Then you should pour fast setting concrete inside to secure your post.