The most effective structure for a formally sheared hedge is with the top slightly narrower than the bottom. Not only does this allow increased sun exposure to lower foliage, but compensates for increased growth higher up.

Plants used for a hedge should naturally be proportionate to the particular application, so that they do not need to be shorn very aggressively, or may not need to be shorn at all. Arborvitaes, as well as hop bush, euonymus, myrtle and some types of pittosporum, are actually better as informal, unshorn hedges where space allows, but need to be shorn where narrow hedges are needed.