How Big Should Hole Be In Bottom Of Pot For Upside Down Plant?
N NE 4th floor corner balcony top of building. glass & aluminum post railing.
Certified GKH Gardening Expert
This will depend, completely, on the plants that you intend to plant.
Usually about 3 inches will be enough for almost anything, but can be too large for smaller plants.
Here is an article that will offer some information: https://www.gardeningknowhow.com/special/containers/upside-down-gardening.htm