We got pressured by neighbours to trim tops of these cedars last summer. When the alleged arborist cut them he ignored the fact there were already dead branches under the growth he cut. It’s been now more than six months and they have not filled in on top. Even worse they are loosing foliage on a side which faces our living room. Any suggestions on perhaps some fertilizer? Is there hope to at least stop the decline? I should add the sections that got most trim are affected and have a small shed on the ground, you can see to the right the part that is lush.
Well, the good news is that your hedge looks healthy and is not in decline even though there are lots of dead branches on top. The fact that so much was removed left no green leaves to continue growth and, unfortunately, new ones will not emerge from the dead branches. This is true of many evergreens. What I would expect will happen now is that the green growth on the top/sides will eventually grow up and over the dead parts. In future, never allow anyone to trim off all the green leaves . . . it is important when you want to keep a hedge to a certain height to prune little and fairly often so as not to create the situation you're now facing. Is it possible that this hedge is Leyland Cypress? If it is, you will probably see fairly quick growth compared to other hedging trees but I believe it will eventually recover a nice appearance if you have the patience to wait a few years.
Cut it down and start over with something new. Something that is not genetically programmed to grow over 100 ft. tall.
@Ron B . . . that is probably good advice though a formidable and expensive job to implement. (I'd consider selling the house before taking on a job like that!) When you say that, I wonder what type of tree you figure these are? Native Thuja or perhaps Leylandii?
Margot is right, they're Leyland Cypresses (Cupressus × leylandii), not Cedars (Cedrus spp.). And yes, they'll be aiming to grow to 35 metres tall, so are not a good choice for small hedges despite being widely sold for that purpose.
Cupressus × leylandii are very widely sold around here because they are supposedly deer-proof and drought-resistant. I planted a short hedge of them several years ago and then went away for a week. By the time we got home, deer had ravaged the trees, tearing off branches and bark (rutting season in October) so I replaced them with Thuja occidentalis 'Smaragd'. When I consider the ongoing pruning requirements of Leyland Cypress, I think it was for the best.
'Smaragd' is a favored winter browse of mule deer in our region. So you have not solved the deer problem. And of course rutting damage by males is not the same as browsing - nobody puts out deer resistance lists that allow for rutting effects.
They wouldn't dare! Having said that, I have never seen mature Leyland Cypress hedges damaged like my helpless little saplings were nor have I ever seen established 'Smaragd' browsed in winter. I keep an eye on such things. The deer around here are Black Tailed Deer, apparently a subspecies of Mule Deer though never referred to as such. To be honest, the Cupressus × leylandii hedges I see in this area (and, there are dozens) are very attractive and beautifully maintained; but if I had such a hedge, it would be neglected because I couldn't keep up with the constant trimming. 'Smaragd' for me!
Wash out my mouth with soap! Of course Smaragd are browsed by deer in winter! The point I was trying to make is that many homeowners choose Leyland Cypress over Smaragd is because they are ignored by deer and are more drought-tolerant. My apologies for confusing the discussion. The Smaragd hedge I replaced the Leyland Cypress one with was, by then, protected by a fence to keep the deer out.
