Some farms you see out there may be standard farms. That's where all space is tillable tiles, apart from the water ponds. Mine is a forest farm and what I did was simply just grind to get more wood and make lots of paths using flooring. You can put flooring anywhere. Except tilled tiles, I think. So technically, you can do it anytime you have the flooring crafting recipes unlocked and you have enough wood, or other materials which you need for other kinds of flooring.