It wont make much difference the trees will fill out more but as they grow 3-5 feet a year in width and height why worry? These trees grow huge and the council may well tell you to keep them at 2 metres or if they interfere with the electricity poles or neighbours you may well have reason to hate them!

thanks for that . should be ok with council and power company as overhead lines finish at the pole and go underground also i have set them well away from pole . they are in middle of my field so no need to worry about neighbours .cheers

Remember leylandi can grow 60-80 feet! It will get very expensive to top them out once they are higher than you can deal with yourself. They also grow to about 10-12 feet in diameter if they're not trimmed. Trim them as soon as they get to the size you require. If you let them grow much bigger ( width wise) you will not be able to trim them back to a much smaller size as they will have lost their inner leaves and will not regrow from branches where all the leaves have been trimmed off.

Remember also to trim them so they are smaller at the top than at the bottom, or they will go bare at the bottom!

These two originals at Leighton are 120ft.

http://www.bbc.co.uk/shropshire/content/images/2005/06/08/leyland_first_180_180x300.jpg

In the open, they are not bad at keeping their lower branches either.

We left some leylandi at the bottom of our previous garden when we moved out 25 years ago. Originally they were 100 feet from us and about 250 feet from neighbours at the back. They are now HUUUUUUGE in spite of us topping them regularly when we were there. Just behind them are some flats built when we left. We had sold to builders after 14 years of being pestered to sell our fruit garden. Awful neighbours moved in and we had to go. I feel guilty when I look at them. They have been there about 45 years.

Nightmare for someone Dorjac? I am amazed that in the 21st century anyone plants them!