This club is located on the right of the courtyard. By joining the Gardening Club, it allows the player to play the mini-game "Insect Rush" once a day for free, but they have to pay 3 AP to play "Break Basketball".
By joining the Gardening Club, it allows the player to meet Jade, but in turn they cannot meet Dajan in the Basketball Club.
Characters who can be found here
However it is possible that other characters can show up in the Garden Club, these are just the most common.