A good hedge has many benefits as a garden boundary. It is a useful weather and dust filter, is inexpensive to create and long-lasting, can encourage wildlife and can be a feature of beauty and interest in its own right. It also offers privacy and security, but problems can occur if a hedge is allowed to grow unchecked.
People do not normally need permission to plant a hedge in their garden and there are no general restrictions on how high a hedge can be grown. The rules that govern the height of boundary walls and fences do not apply to hedges. Existing common law rights entitle people to cut overhanging branches back to the boundary line, but they do nothing about hedge height. The provisions contained in section 198(6)(b) of the Town and Country Planning Act 1990 may apply, particularly to overhanging parts of protected trees i.e. trees in a Conservation Area or the subject of a tree preservation order.
If someone is troubled by a neighbour's hedge, the best way to deal with the issue is to talk to them about it and to try to agree a solution.
Where negotiation fails, Local Authorities in Wales have powers to deal with complaints about high hedges under Part 8 of the Anti-social Behaviour Act 2003 ("the Act").