草墙 is a background 墙 that is purchased from the 树妖 for 10 each. It functions like other walls, while having a distinct green, speckled texture akin to moss or leaves. It can generate naturally in above ground tunnels and grottoes in 森林 生物群落s. Like natural 土墙s, these can not be collected and does not affect 敌怪 spawn rates.
Note that naturally spawning grass walls are not considered valid for housing, but grass walls purchased from the Dryad can be used as walls for houses.