The Garden is an open field, North of the Kitchen, and South of the bathroom. It also allows access to the basement/dungeon.
The Garden is key to your survival, as it respawns 3 random herbs everyday. These can be Green (common), yellow (Uncommon), or Red (rare), and for free. These are not only potent Healing items, but can also be exchanged for their Tea (upgraded) equivelants.