How to help our very tall hedges grow thicker?
GBoudreau
Posts: 1
We have about 50 meters (165') of hedges between our row of townhouses, and the row behind us.
Depending on the trees around it, it is between 10-12' in height, approximately.
You can see it on Google Maps here: https://www.google.ca/maps/@45.5147129,-73.6313767,126a,35y,45t/data=!3m1!1e3
and in those pictures: https://photos.app.goo.gl/1zFueAfZMEmUv80m2
We are in Montreal, Canada.
Our problem with those hedges is that they are getting more and more sparse; we see more and more through it, every year.
We had very different opinions on what we should do with them, to help them grow thicker.
Should we cut their head, maybe to something like 8-9', and give them enough earth+compost+fertilizer?
We were told by some people that those kind of trees should not have been left to grow this tall, but that if we cut their head too much, they're going to die. Others are saying it's fine to cut their head as much as 3-4', as long as it's done in the autumn or spring.
Ideas?
Thanks.
Posts
They have been left too long in all honesty and have grown upright and thin in direct competition with their neighbours.
Cutting the main stem of Leylandii will stop the main trunks growiing taller. The side shoots will fill out, particularly near the top, creating denser foilage that will need at least annual trimming to keep it in shape.
As for the lower section of the trees.... cutting the top section down is a gamble and the lower parts may never thicken up. The trees may live, they may die but one way or another, it's going to be a potentially expensive process.
Cutting the tops off Leylandii is one thing but the pics of some of yours suggest they have been trimmed to a degree at the side - and this is good. As there sees to be plenty of fresh, green side shoots that have been previously trimmed, those sections may survive having their upper section removed.
The worst thing you can do for conifers is to cut the side shoots all the way back to brown wood; this will likely kill them very quickly. When vastly overgrown, they need light triming and never cut back further than the innermost couple of layers of green foliage during a trim. If there isn't any on the side branches, iy may be game-over