When to top a new leylandii hedge tree

I've got a 7ft tall leylandii hedge and one of the trees was replaced a few years ago. It’s now reached just above the rest of the 7ft hedge height.

I wondered when I should cut the top off. Now, when it’s just reached the height I want so it’s a very thin stem right at the top, or should I leave it grow further to make the stem thicker at the top, if so how high until I do?

Thanks

 

Basically it's up to you. Most conifers unlike other trees will not sprout new growth from cut tip. New growth will appear from below the cut end. This will cause the Leylandii to spread out more.

 

I like to do Conifer work in the autumn as you will have all winter with it looming neat.

 

I agree with Steve. Autumn is a great time to cut back as you get the benefits all winter. Another cut in Spring is usually ideal.