Yes—an urban planter box can be an effective way to grow a privacy screen on a balcony, but the planter itself must be suitable for the job. A small decorative box with shallow soil will struggle to support tall, dense plants. For a real privacy screen, choose a planter that is at least 35–45 cm deep for climbing plants or compact shrubs, and make sure it is wide enough to hold a sturdy trellis and a healthy root system. If you are growing bamboo, choose a clumping variety and allow even more root space. Also check the balcony's weight limit; wet soil is heavy, so use lightweight potting mix, pot feet, and casters where appropriate, and avoid overloading one corner.
Drainage and stability are just as important as size. The planter needs drainage holes, a slight gap beneath it, and a saucer or tray that does not leave water standing against the balcony floor. A balcony privacy screen catches wind, so secure the trellis to the planter rather than relying only on a railing. If the building allows it, anchor the planter or trellis discreetly for extra safety, and choose plants that suit your sunlight, wind exposure, and winter conditions.
For the screen itself, use the planter box as the base and add a trellis, tension wires, or a light frame. Good candidates include star jasmine, clematis, passionflower, honeysuckle, climbing ivy, or compact climbing roses, depending on your climate. In shady spots, try ivy or a shade-tolerant climber; in full sun, flowering climbers can create a softer, more attractive screen. For a faster, lower-maintenance option, use tall ornamental grasses or a clumping bamboo in a deep planter, but keep the mature height in mind.
Finally, expect some maintenance. Privacy plants in containers dry out faster, need feeding during the growing season, and may need pruning to stay dense without blocking light or crowding the balcony. With the right planter box, trellis, and plant choices, an urban planter box can absolutely grow a practical and attractive privacy screen on your balcony—just start with a deep, stable, well-drained container and check your building's safety rules first.