To set a post, you need a post hole. For a typical 4-by-4 post up to 8 feet tall, make the hole 1 foot in diameter and 2 feet deep. Fences up to about 4 feet high can get by with 1-foot-deep holes. Here's how to dig one.
It's not easy work, but soaking the soil first will save you some time and trouble. To improve water penetration, drive a length of rebar or galvanized pipe a foot or so into the earth, wiggle it out and then follow with the hose. Repeat this in several places, and let the earth soak awhile before you dig.
A little technique helps speed the work. To begin, use the post-hole digger as a chopping tool, as the animation shows. Keeping the blades spread, lift the tool and drop it, letting the weight of the digger do most of the work. Rotate your way around the hole. Don't bother scooping out the earth until you have a good pile of loose soil in the hole. Then, plunge the digger down, spread the handles and lift, removing enough earth to expose fresh stuff to chop. As you go deeper, also go wider. (The sides tend to cave in on their own.) Try to dig a hole that's a bit broader at the bottom than at the top. The shape helps anchor the post's concrete base against tipping, and the extra weight at the bottom adds stability.
Tip from the pros: This can be a strenuous job, so save your back. Bend at the knees and use your legs to help drive the digger and lift out the earth. Wear work gloves to protect your hands. Finally, if you have more than a dozen or so holes to dig, don't fight it: Rent a power post-hole digger. They're noisy and bone-jarring when you hit rocks, but they speed the task greatly. Use safety glasses and hearing protection when you're running it, and enlist a friend to help. It's not a one-person job.
