Leylandii can grow up to a metre a year.

(Leylandii, a fast-growing conifer variety that has been called the scourge of suburbia, is now subject to anti-social behaviour laws in the UK. A few years ago the government estimated there could be up to 17,000 unresolved neighbour disputes over high hedges. Under the new powers, local authorities will be able to intervene in leylandii, and other high hedge, disputes. Officials will have the power to order hedges to be cut back, to a maximum of two metres high.)