Setting wooden posts in concrete makes a permanent installation. Improperly setting the post in concrete will cause the wooden post to prematurely rot inside the hole. Preparation is key to setting the post as the holes should be dug to the proper depth before setting the posts. In most cases, the overall depth of the hole should be one-third the length of the post. The diameter of the hole must also be larger than the post diameter. Typically a 6-inch diameter post should be set in an 8-to-9 inch diameter hole.
Place two to three large shovelfuls of gravel into the hole.
Set the post into the hole. Tamp the gravel a few times with the wooden post.
Mix the concrete according to package instructions.
Fill the post hole with the concrete halfway full. Move the post from side to side to settle the concrete around the post.
Check the post for levelness with the 24-inch level. Place the level, alternating on two sides of the post, 90 degrees apart. Make sure the bubble rests between the two level lines.
Fill the post hole with the remaining concrete. Check for level. Add 3 inches of concrete around the post above ground level.
Contour the concrete with the hand trowel so it falls away from the wooden post. In other words, you will want water to fall away from the wooden post and not towards it.
Check the post for levelness one hour after adding concrete. Make final adjustments as necessary.
You can use two bracing stakes to hold the post level while adding the concrete and until the mixture is firmly set. In most cases, when the concrete is mixed to package instructions it will begin to firmly set in one hour after mixing. Check with local utility companies before digging holes around your home or property. Utility companies will come out and identify all underground wires and pipe locations before you dig.