Hi there.You are right,once you cut back to the brown 'stuff'as you call it the green growth WILL NOT return.In my job as a self employed arborist I see this problem all the time.Some hedging plants will re-grow if you cut them back hard eg laurel & privet but not your conifers I'm afraid.You have two choices.A,Trim about half of the length of the green growth off(very carefully)B,Cut down the hedge and start again.Once the hedge gets to the required height and width trim it twice a year religously and you will have a compact affective boundry that will be great for you and the birds who like to nest in it!

I'm confused now! The first reply and the first comment appear to be in complete conflict. I'm trying to keep the balance between privacy for my garden and not being a nuisance to my neighbours, with regards to the leylandii along the border but in my garden.

A couple of years ago several feet were cut from the tops of my trees - it looked awful from the upstairs windows - but the tops have grown back ... and up ... and now they need doing again. So, I'm confident that the tops will grow back, but what about the sides? My trees are several feet wide, most of it the"empty" brown space up to 2ft or so radius from the trunks. Can I get the sides cut back or not?

I have chopped my side of a line of 6 leylandi, forming a "fence" of stripped poles.....Sounds mad eh? I am using them for honysuckle, clemitis and hopefully a rambling rose which given the right care will form just as an effective privacy barrier, as the poles stand around 8ft. From the other side i have just shaped them back to tree! Instead of wall. I think it will look amazing........

What is the correct answer to cutting back to brown wood. If yes, how long before new buds appear.

my dad moved into his house about 4 years ago and had this problem. however, being skilled in all things horticultural he cut it back to the brown wood and it has grown back now into a lovely, tight, thick dark green hedge. obviously he has to trim it to keep it that way but its much nicer than it was. i recently moved into a house with a 10ft leylandii and my dad just cut it back to the brown and tells me it willgrow back to dark green and tight, but it will take a few years to look great. it think its worth it though. the top of it looks awful but he assures me that that too will look good in the end too so ...from my own experiences...cutting it back will look bad at first but it SHOULD grow back lovely, tight, and dark green -- Jen

We've been in the same situation and cut back to brown wood on an overgrown leylandii hedge and new growth started appearing within 2 weeks. I suspect that, as the previous commenter said, it will take quite a long time for it to look decent. We got a foot of space in the garden though - it's worth it.