Yes, you can grow climbing roses in an urban planter box against a wall, but it works best when you treat the planter as a long-term container garden rather than a small pot. Climbing roses need more root space than many patio plants. Choose a compact climbing or patio rose rather than a vigorous rambler, and use a container that is at least 45–60 cm wide and deep, with 50–70 litres of soil or more. A light-coloured pot can help reflect heat in hot city sites, and sturdy castors make a heavy planter easier to move.
Place the planter where the rose gets at least six hours of direct sun. Against a wall, check for reflected heat and rain shadow: the wall may bake the plant in summer and block rainfall, so water regularly and mulch the surface to keep moisture even. Good drainage is essential; check drainage holes and use a soil-based compost mixed with grit or perlite. Raise the pot slightly on feet so water can escape.
A wall-trained climbing rose needs a support. Fix a sturdy trellis or wires to the wall, or use a freestanding obelisk if drilling is not allowed. Keep the support a few centimetres away from the wall to improve airflow and make tying in easier. Train the long shoots horizontally or in gentle arches; this encourages more flowers along the stems. Tie stems loosely with soft twine, leaving room for growth.
Container roses dry out faster than garden roses, so water deeply when the top few centimetres of soil feel dry, especially in summer. Feed with a rose fertiliser through the growing season, following the label. Prune in late winter or early spring, removing weak or crossing stems and shortening side shoots. Watch for aphids, black spot, and powdery mildew, and choose disease-resistant varieties to reduce problems in a crowded urban setting.
In cold climates, move the planter to a sheltered spot or wrap it for winter, because roots in containers are more exposed to frost. In very hot climates, protect the pot from harsh afternoon sun and keep the wall from overheating the foliage. With a large container, reliable support, and consistent care, climbing roses can thrive in an urban planter box against a wall—provided you choose the right variety and keep up with watering and pruning.