The Tree of Peace, commonly referred to by players as the "ToP" is the first big quest line you will encounter in Charm Farm, and begins upon reaching Level 9. There are currently 50 levels total.
There are Level requirements you must meet before you can upgrade. You must be 8 Levels higher than the next upgrade at the higher levels of the tree. (This changed recently from 7) Which means, if you want to upgrade your Tree of Peace to L20, you must be Experience Level 28 in order to do so.
To view the details for the payout, click on the image of the level you want to view. If you have levels that we are missing, please post a pic in the comments below of the Production window before starting a production.