Yes—generally you can install an urban planter box on a brick wall, but it is not simply a matter of drilling two holes and hanging a box. The wall type matters first. A solid brick wall may be able to carry a modest wall-mounted planter when suitable masonry anchors are used, but brick veneer, cavity walls, and older mortar should not be trusted to support a heavy planter without engineering advice. If the brick is a veneer, the planter should be tied back to the structural wall behind it rather than anchored to the veneer alone. Check with a structural engineer or experienced contractor if you are unsure.
Weight is the next issue. Soil becomes heavy when wet, and a large planter can impose a significant dead load plus wind load. Choose a lightweight planter box, use a lightweight growing mix, keep plants compact, and avoid oversized units. Stainless steel or hot-dip galvanized brackets are best for durability. Use anchors rated for masonry and the expected load; do not rely on plastic plugs or shallow screws. Spacers can create a small air gap between the planter and the wall, and flashing or a waterproof backing should protect the brick from staining and dampness.
Drainage and irrigation need planning. Water should drain away from the wall, ideally into a removable tray or controlled outlet, not down the brickwork. Drip irrigation can make maintenance easier, but it must be checked for leaks. Also confirm local permits, fire egress rules, landlord or HOA approval, and access for pruning and repairs. With the right wall, hardware, waterproofing, and maintenance plan, a wall-mounted urban planter can be a practical and attractive feature. If the wall is unsuitable, use a freestanding planter, railing bracket, or ground-level system instead.