Hi Pertovski,
I would suggest that your answer will be found in what the strata plan says. You need to find the definition of the stratum of your lot, as these planters could be completely within your lot.
Even still, the decision to not maintain common property or even to alter common property will require a special resolution at a general meeting.
I would suggest trying to establish what may be involved in what you may prefer to occur (scope and cost) and put that to the EC as a solution to the present situation.
Mr S