A planted panel is a sail. What that means for what you build, why nobody can give you a number, and the design choices that reduce the load itself.
A railing planter is fixed to a railing, not resting on it. How the attachment works, what it carries, and when to ask first.
A tiered shelf moves the weight to the floor, which removes one risk and adds two: tipping over, and point loads through four small feet.
A tower touches no wall, which trades pull-out risk for tipping risk. Here is how stacking planters really behave, and what to check before you buy one.
How many plants a vertical garden holds is a weight question first. Plan for mature spread, airflow and water load, not a full wall on day one.
On a balcony the constraints pick the structure, not the other way round. Wind, water, permission and reach, before you choose anything to buy or build.