For a rental, the safest approach is to keep the planter completely freestanding and put a waterproof barrier between it and every surface. The best renter-friendly urban planter box is usually a lightweight, self-watering container with an integrated drip tray, rubber feet or felt pads, and a design that does not require drilling, screws, or adhesive hooks. This gives you greenery without risking wall holes, paint damage, or water stains on the floor.
A few practical options work well. First, choose a freestanding rectangular planter with a concealed saucer. Look for powder-coated metal, UV-resistant resin, or wood-composite models with adjustable feet. Add felt pads under the feet if they are not already rubberized, and place a thin waterproof mat underneath for extra protection. Second, consider a fabric grow bag set inside a decorative outer planter. Fabric bags are lightweight, breathable, and easy to move, while the outer box catches drips and looks tidy on a balcony or beside a window. Third, use a self-watering planter with a separate water reservoir. It reduces overflow and keeps herbs or small vegetables happy without daily watering. Fourth, if you want vertical interest, use a freestanding trellis planter rather than attaching a trellis to the wall. The planter supports the climber, and the wall stays untouched.
For balcony railings, a saddle-style railing planter can work if it hooks over the top rail without screws or clamps that mark the surface. Check that it is stable and does not block drainage or safety routes. Avoid heavy ceramic pots on floating floors or balconies, and do not overfill large containers with dense soil. Use a lightweight potting mix and leave a small gap below the rim to prevent water spilling over. A plant caddy with locking casters makes it easy to move the planter for cleaning and protects the floor from scratches.
Finally, keep plants slightly away from walls to allow airflow and prevent moisture marks. Water carefully, empty the saucer after heavy rain, and use a watering can with a narrow spout. With a freestanding, lightweight planter, a drip tray, and floor pads, you can enjoy urban container gardening without leaving rental damage behind.