What is this secret? Simple; just set the plants on top of the ground in their pots with the bottoms cut out.
I am going to do a combination of Leyland Cypress and other fast growing evergreen shrubs such as Thuja Green Giant for this stretch of about 200'. To plant all of one plant species or cultivar in an area is inviting problems with disease and insects hoards. I will be sprinkling some good compost and root stimulator in the area where the pots will sit in order to make the roots want to grow into the compost and down into the ground. The area is quite fertile as it is after decades of leaf drop so the bushes should be quite happy there.
Once the shrubs are rooted well into the ground in a couple of years I will cut off the pots and surround the root ball that is above the ground with a bunch of straw and leaves. Eventually, it will settle down into the surrounding ground and continue to grow on far past my lifetime.