Until the end of the eighteenth century bleaching was restricted to the period from March to October. Because bleach greens operated in the summertime only, their owners had to acquire reliable and inexhaustible supplies of water. The consequence was that the major greens were soon to be found along the banks of those rivers that continued to provide a good flow of water in summertime. When this linen was watered regularly as it lay on the green, the process was termed `wet bleaching'.
It was considered superior to `dry bleaching' by the Cootehill method. The number of bleach greens reached a maximum of 357 in 1787, but after this the number fell rapidly as bleaching methods continued to improve. By the 1850s there were only forty coping with many times the quantity of cloth finished in an eighteenth-century green.