There is a row of large planters outside my workplace. Each one is about the size of a bathtub. Each one has this capped white plastic tube the thickness of a beer can that sticks in halfway in the soil at a slight angle and doesn't appear to be connected to anything. What is it for?
it could be a clean out for the under drains. planters can become water logged if they have no drain. this orifice may also a pressure washer hose or vacuum to clean the line.
I could be a hole in the soil in which to pour water, and the pipe keeps the sides from caving in, whilst it would likely have holes in it, allowing for the water to be soaked up by the soil.
