Whether you live in Scandinavia or in the US, it seems that people have great difficulties in trimming a hedge correctly. Even people who are responsible for the maintenance of green areas as professionals has obvious problems with this.
Actually, I think many instinctively realize that something is wrong when the hedge is at its narrowest down at the base and wide and shapeless towards the top. But it’s not always easy to put your finger on what is wrong. I will tell you exactly what you must do:
The hedge should be at its narrowest in the top and at its widest at the bottom.
The narrow part will let maximum sunlight trough the bush, stimulate new growth and prevent disease. The wider bottom will smother weeds and shade for the roots and cause the hedge to require less water. It is also the best way to avoid damages after heavy snowfall.
This is an indisputable assertion and it annoys me deeply that not even professionals know this. Cutting a hedge like this is perfectly logical if you just think about it.
7/30/2020: Edited for clarity