Hemp Tycoon, is a new game at Adult Swim. It's a pretty awesome game if you ask me. You grow hemp and harvest it for a profit with Hempy. It's set in real time so each plant has a base amount of time that it takes to grow the plant and another amount of time before the plant withers away and can't be harvested.
You can also place items on your areas to help you out.
There are plants that can take days to grow and will continue to grow even if you don't have the game open. It has a save game button but I'm not really sure how it works since I haven't found a way to load from that position.
Go and enjoy harvesting your own hemp!