Putting pot plants on balcony exterior walls or balustrades is insane. Chances are that the balcony is common property so the owners corp can (and should) pass a by-law that stops this ASAP.
Given the probability that we are all going to be suffering more and more extreme weather, including high winds in the future, this should be stopped now.
I imagine your insurers might be alarmed that your block has potentially lethal plant pots on balconies. And if you think that’s an exaggeration, think about the poor bloke who was killed by a flying gas bottle just two years ago.