How To Properly Dig a Hole and Amend the Soil
When I dig a hole, I use the DPM Method (Dig, Phlip, Mince). If I am working on a lawn, I remove all the sod by skimming it off the top of the soil and throwing it on the compost pile or in the trash. I strongly advise doing this before you begin your hole. You will need a shovel and a tarp. The purpose of the tarp is to prevent losing any soil onto the turf or to keep the mulch clean. The tarp keeps the mess to a minimum, and there is always enough soil to go back in the hole. It is advisable to keep the topsoil and subsoil separate by placing them in two different piles on the tarp.
Step 1: Plunge the shovel deeply into the ground.
Step 2: Phlip the soil over directly on the top of the future hole.
Step 3: Mince the phlipped clump of soil as finely as you can.
Step 4: Once you can no longer dig out a hard chunk of soil, shovel all the finely minced soil onto the tarp. The placement of the tarp should be in the yard for trees and next to the hole in the flower bed for shrubs or flowers.
Step 5: Repeat Steps 1-4 until your hole has been dug to the desired size.
When you begin to plant, put the subsoil and topsoil back at the same levels where they had been in the soil horizon. You can tell where each should be placed by the colors of the soil in the hole and your two soil piles on the tarp. This will promote really good drainage and prevent the subsoil on the surface from making the water run away from your plants instead of soaking in. This often happens with clay based soils.
Now, a word about amendments. If your soul is of poor quality, you may want to amend it. Amending soil means adding some good stuff like peat moss, compost, topsoil, and, my personal favorite, fine grade pine mulch.
Amending soil is tough work. One way to make it easier is by layering the different amendments on top of each other. I like to do a lite amendment, then a heavy one, followed by another lite, and then finishing with a heavy. For example, I do a coarse dry peat (lite) followed by a composted manure (heavy). I add another lite amendment such as pine bark soil conditioner, and I finish with a heavy one such as a fine rich black peat. I use a steel garden rake to thoroughly mix the amendments.
Before you begin digging, you can layer the amendments near the spot of the future hole. Then Dig, Phlip, and Mince them with your native soil.