It creates a thick barrier from untidy, gappy and straggling hedges. Stems are cut most of the way through so that they can be bent over without damaging them.
Depending on the style of hedge being laid, it is frequently strengthened with vertical stakes and horizontal binders, as on the Midland style hedge shown on the left.
Over many years, the laid stems, called pleachers, tend to gradually die back. However, long before then, a new hedge will have grown up from the base of the existing hedge.
Hedgelaying has great conservation and wildlife value and is likely to take place every 15 years or so with periodic trimming inbetween to encourage regrowth and keep it tidy. Managed in this way, hedges can last indefinitely.
Hedgelaying is seasonal work taking place between autumn and early spring. It is avoided outside these periods to avoid disturbing nesting birds and trampling plants growing in and by the hedge which could contravene the Wildlife & Countryside Act.
It is not the size of the gaps in your hedge that matters, but whether the height of the hedge will allow the hedgelayer to fill the gaps.
Unless you want a low hedge or in special circumstances, such as a garden, a hedge less than 8 feet tall is likely to be better left to grow taller before it is laid. An individual is only likely to ever pay once for a given length of hedge to be laid so it should only be done when the hedgelayer can achieve a good result.