Posted: 20/05/2015 at 21:26
Don't let them produce more than a few cherries - pick most of the embryo ones off soon and discard them if you can bear it - the less the trees have to do the better they'll cope with their situation.
If they've not had any yet this year, I'd give them some Fish, Blood & Bone (as directed on the pack) as the Leylandii will be taking all the nutrients as well as all the water out of the soil.
Well done on getting rid of the concrete! You're getting there