When you are carrying a Seed and are in an Overthrow zone that has an open spot in which to plant it, a diamond-shaped waypoint will appear to show you where it can be found if you are within a certain (relatively large) distance. Running the perimeter of each zone and cutting across a couple times should provide you enough information to locate any unused planting locations. [i]Edit: also note that until a few weeks ago it was possible to continuously earn additional Seeds from completed Overthrow activities even if you had filled the planters in all three zones. I currently have 26 extra Seeds I can do nothing with as I have filled all of the slots in each zone.[/i] (΄◉◞౪◟◉｀)