How do I aggressively trim a cedar hedge?
Growl while you do it. Okay, seriously – the proper way yo do that is NOT to use hedge trimmers. You want hand-pruners, and you go in and follow individual branches down, and basically remove about half of them to the height you want – whatever height you want, really, as long as you’re not taking more than a third of the total height off, it’ll be fine. That will let sunlight in, and with any luck, it’ll put out some growth where the sun hits it. The top will be spotty and full of holes, but not a barren wasteland. Then next season, when there is new growth on what you cut, go in and take down the ones you left tall. It’s time consuming and more labor intensive…but your other solution is to shear the whole top off which will leave you with an ugly and naked top for a long time. Still feasible…but it’s just a matter of aesthetics, and which you can put up with better.