Hi i would like to collect a lot of monsters in the game. The monster barn is big. Do i have to always always make tons of grass ? Seems it can't be purchased at the shops... Do they leave if you don't feed them ? How many grass zones do i need to be not negative ?
The amount of needed grass is dependant on the monsters, I think. Other than that, I'm not sure what happens if they don't get fed, other than them not recovering from being tired. I'm sure your friendship will decrease after awhile of not feeding.
I have a big field of grass right outside the barn. It started small, but I expanded it by getting seed from picking the grass. It's not that hard to keep up demand.
Buy Grass Seeds from Shara's shop. As for how much feed you need, one room of monsters (regardless of amount of monsters) need 1 Grass each day. The grass you planted will initially give you 1 Grass per day, but after some time, they will begin to grow slower (up to the point where they give 1 grass every 4 days or so), so it's safer to plant more seeds than you might think you need or do some crop rotation.