Registered Parks and Gardens
Historic England includes Registered Parks and Gardens on the National Heritage List for England. If your green space is important to people all over the country, then it might be able to be added as a Registered Park or Garden on the National List which is looked after by Historic England.
The emphasis of the Register is on gardens, grounds and other planned open spaces, such as town squares. The majority of sites registered are, or started life as, the grounds of private houses, but public parks and cemeteries form important categories too. Even hospital landscapes and two pumping stations are included, because they have skilfully-planned surroundings reflecting the landscaping fashions of their day. The emphasis of the Register is on 'designed' landscapes, rather than on planting or botanical importance.
Historic England
Historic England provide lots of guidance on what kinds of landscapes, parks and gardens can be added to the register and how to apply for your space to be put on the list