I'm having trouble growing a consistent amount of seeds. I have the Fence, I Parterre, French Window and Grass all within one square of each other. When I click the Grass, the total number of seeds I can grow is 10. If I move the Parterre downstairs to the middle of my tent and leave everything else upstairs, the amount changes to 30. If I move just the Fence downstairs, the total amount I can make changes to 20. I have a Mill and it makes no difference where I put it. What's up?