The trick with screen planting is not to plant them in a strait line.
Plant them in a zig zag .
It is a lot better for the trees and will make the screen fill faster.
work out where they will go, flatten the ground place water saturated paper over the entire bed then make a hole in the paper to plant your trees.
Cover the paper with pine bark and if you want edge it with lawn edging to prevent grass invasion.
Thus you will have to do almost no maintenance on the hedge other than hitting anything that sprouts in the mulch with glyco.
If the trees grow at different rates it will not look stupid like a strait line hedge does and if a tree needs replacing in the future it will have a chance of growing.
Spacing should be around 1.5 times the supposed spread of the tree you are using
