Remember that plastic can easily topple above if filled with light-weight soil. To prevent this, fill the bottom with a few pebbles for added balance. I haven't tried making use of this method for cleaning terracotta pots in the fountain prior to, so I'm able to’t say for sure. https://flowerpotsdesign39505.verybigblog.com/27920707/facts-about-large-patio-plant-containers-revealed