Harvesting is a mini-game in which you harvest various Sanctuary fruits and vegetables to use in cooking, another mini-game (note vegetables or fruit that are harvested from a farm will not work in cooking, only from the harvesting mini-game). The objective is simple, you just have to connect the various fruits and vegetables in rows of three or more. Once you've harvested enough fruits and vegetables in a certain category you will get one bushell of that certain vegetable or fruit.
There are also certain objectives you have to complete before you are classified as winning the game. Some objectives require you to aquire a certain amount of bushells of a certain fruit or vegetable or to make a certain length of a chain of fruits or vegetables. There is also a time limit that once it runs out the game is over. More time can be gained by harvesting fruits or vegetables.
Finally there are also power-ups that enhance your chances of winning, such as wild tiles or ones that will mix up the board. If there are no more matches left on the board it will reset but you will keep your bushells.