Hedges are clean and beautiful when they are pruned regularly. Regular pruning and shaping can influence the growth rate and density of the hedge.
There is a distinction between an adult hedge and a forming hedge. The adult hedge needs maintenance pruning. A forming hedge needs pruning and shaping to encourage healthy growth and the development of side branches while avoiding bare trunks at the base of the shrub.
Pruning and shaping of regular hedges:
Roughly cut the sides of the hedge to a same size during the first years after plantation. The base must be slightly larger than the top, so that all the branches take advantage of the sun. Remove 30 to 40% of the year's growth until the hedge has the required height and width. Prune the top only when the shrub has reached the desired height. In the meantime, cut only the side branches.
In a few years' time, your hedge will be fully grown and will only need yearly maintenance pruning to keep it beautiful.
When is time to prune the hedge ?
The best moment to prune a flowering hedge is right after blooming.
The best moment to prune regular or screening hedges depends on the variety of shrub that composes it.
For a deciduous tree, prune in spring (April) then at the end of September.
For a conifer, prune in June to enjoy the spring shoots. Do not prune after September, as the cuts would not heal well.