How to grow a formal hedge
Formal hedges
To plant a formal hedge, space shrubs more closely than usual, typically setting them only one-half to one-third as far apart from each other as the planting directions indicate. However, do leave the full recommended spacing between plants and a walkway or other permanent barrier. Otherwise, you’ll end up doing more than the desirable amount of pruning to keep the plants in bounds, and the hedge will show a lot of bare wood.
In most cases, you’ll prune shrubs at planting time to force branching and encourage a thick hedge that’s foliaged to the ground. Cut back larger deciduous plants by about a third, smaller ones to within several inches of the ground. Also cut back fast-growing broad-leafed evergreen plants, but less severely than deciduous sorts. Don’t head back slow-growing broad-leafed evergreens or conifers; just shorten their lateral branches.