In this post about Germany by car: main signs on the highways, ecological zones and the prohibition of diesel, parking signs.
In France, there is a special website that lists all available gardens and parks, down to the smallest amateur ones. It can be difficult to assess the level of the garden there. In Germany, there is no such site, and finding gardens and parks is not so easy: gardening farms will come up with a search.
In this topic I collect German gardens, parks and flower fields that I know. Gardens at palaces, if they are important as an independent unit, are also indicated.