Gist: the "potato order" is historical, but that he tricked people by having his soldiers guard potato fields in order to make them look desirable to the farmers is a legend which can't be proven one way or the other. Whatever he did, it worked, whereas Dad FW had already tried to introduce the potato to Prussia and failed.
Potato grave: no idea, could not discover by quick googling. Must dash!
Re: Sanssouci
https://www.die-kartoffel.de/31-blog/stories/191-friedrich-der-grosse
https://www.br.de/radio/bayern2/sendungen/kalenderblatt/2403-friedrich-ii-empfiehlt-kartoffeln-100.html
https://de.wikipedia.org/wiki/Kartoffelbefehl
Gist: the "potato order" is historical, but that he tricked people by having his soldiers guard potato fields in order to make them look desirable to the farmers is a legend which can't be proven one way or the other. Whatever he did, it worked, whereas Dad FW had already tried to introduce the potato to Prussia and failed.
Potato grave: no idea, could not discover by quick googling. Must dash!