This is a case where the way
"everybody does it" is the wrong way! Take a look at most hedges and
you will see them trimmed like "B" above with the bottom wider than
the top. What this does is block sunlight from hitting the lower
parts of the plant. Leaves need light in order to maintain
themselves so, lacking light, the branches on the lower parts are
leafless. Since hedges are normally intended to block the view from
one side to the other, this is not acceptable.
The proper way to prune a hedge is,
of course, like picture "A" above with the bottom tapered wider than
the top. This will allow full sunlight to hit all levels of the
plant so they can maintain foliage from top to bottom. The hedge
will look and function to the best of its ability.
