`The problems with Leylandii, in my opinion, are: 1. They look horrible when the natural flora consists of mainly Oak and Ash 2. Nothing wil grow under them or for some distance either side of them 3. Uncontrolled (and they get out of control very quickly) they cut the light for considerable distances and do not provide much privacy for the bottom two metres My neighbour in France is cursed with these trees - he didn't plant them - and has had to pay a fortune to cut them back ( and when cut back they look horrible too) and they still cut out the evening sun from our garden. My neighbour on the other side planted some despite our polite request not to: fortunately they died (the trees not the neighbour and nothing to do with me just drought and deer) which made us extremely happy. They are horrible trees not even any good for firewood.