Little is known of the early history of the gardens, but it is assumed from the great age of many of the specimen trees that they were laid out at the time the mansion was built. It is possible that at least part of the gardens existed prior to that date, since the former mansion house, known as Old Mertoun House – now the head gardener’s house in the walled garden – dates from 1677 and nearby is a well preserved, circular dovecot dated 1567, thought to be the oldest in the county.