Game is in quite the early stages.
I don't know if dev has mentioned it elsewhere.
But in DMS the said that farming will be easier in a later build.
I personally suggested sprinklers, but they are likely going to go with having the girls help out as farmhands.
Again it's an early build, and currently they seem to be focusing on H-content (no surprise there).
Which is likely why you don't really need to do much of the farming and mining right now as they are WIP aspects of the game. (outside of needing the crowbar for the window scene).
In case you didn't know, there's infinite wine in Mothers fridge.