For a lightweight urban planter box that is easy to move, start with a recycled plastic or resin planter on locking casters. These are weather-resistant, affordable, and much lighter than concrete or ceramic. Choose one with pre-drilled drainage holes, a removable saucer, and handles or wheel-friendly feet. A 30–50 liter size is usually the sweet spot: big enough for herbs, salads, or small flowers, but still manageable when filled with damp soil.
If you want a modern look, powder-coated aluminum planter boxes are a strong option. They stay light, resist rust, and look clean on balconies and patios. Add a wheeled plant caddy so you can move them for sun or cleaning. For herbs and shallow-rooted greens, fabric grow bags with reinforced handles are very lightweight and easy to shift, though they dry out faster.
Before buying, think about the weight of wet soil rather than just the empty planter. Use a lightweight potting mix, avoid overfilling, and check your balcony's weight limits. Locking casters are useful on windy balconies, and a self-watering insert can reduce watering trips. A good all-round choice is a UV-resistant recycled plastic planter with drainage and lockable wheels; it balances price, portability, and durability for urban gardening.