Leylandii tips going brown after trim

Hi

I was wondering if someone with Leylandii experience can help me...

I've just purchased a house with a long (30m maybe) Leylandii hedge. It needed a good trim, it was extending over the pavement quite a bit. I read online not to cut back to the brown as it won't grow back. So I cut it back quite a bit, leaving green, but probably only a few cm. Length varies. After a few days on close inspection the tips are all going brown all along the length. I'm very worried I've damaged it or its dying. See attached image.

Does anyone know if it's OK or have I trimmed it too much and now it's dying or something?

Thanks

 

When we cut leylandii back to far we cut into the part that has sap. When the sun comes out it burns the sap and that's why it turns brown. It usually recovers after time. I wouldn't worry about it no long term or severe damage is done. Your ones have minimal burn.

 

It's leylandii. I'd have cut it back a bit more. Like, to ground level

 

My experience with the them is unless you cut back (width) from an early age so that you can keep them green and `slim` then they end up a major problem.
Mines got too wide but managed to trim back just short off the brown wood and they always recovered but looked awful for a while.
Thankfully none in my current garden.