This is a common concern for city gardeners. The short answer is: it depends heavily on the material and construction. Not all planter boxes are created equal when facing severe weather.
High-quality planters made from durable materials like fiberglass, thick polyethylene, or powder-coated steel have a much higher chance of surviving hail impacts and high winds. Their structural integrity is key. Look for features like reinforced corners, substantial wall thickness, and proper drainage holes that won't compromise strength.
Conversely, thin plastic, untreated terracotta, or ceramic pots are highly vulnerable. Hail can crack or shatter them, and strong winds can easily topple lightweight, top-heavy designs.
To improve storm resilience, ensure your planter has adequate drainage to prevent waterlogging and becoming dangerously heavy. Secure it in place, especially on balconies or rooftops, using brackets or weights. For hail-prone areas, having a temporary cover or moving planter boxes to a sheltered spot when severe weather is forecast is the most reliable strategy.
Ultimately, investing in well-made, robust planters designed for outdoor use is the best defense, allowing your urban garden to thrive through the seasons.