Garden Festival
From Kokorodatabase
To be fairly truthful? Even a majority of the school's students aren't interested in this.
But nontheless, the Garden Festival is a big staple in Garden life, according to Selphie Tilmit, who heads the festival committee. The Garden website has its own page for the festival, as well.
Charice is also known to help out, which probably explains the floral decorations.