If your balcony faces north, you are gardening in soft, indirect light, not total darkness. That changes what “best” means. The ideal urban planter box is not simply the biggest or cheapest one. It is the box that helps you manage moisture, reflects weak light, fits your space, and makes it easy to grow shade-tolerant plants without constant fuss.
For most north-facing balconies with little sun, the best choice is a self-watering, light-colored rectangular planter box with wheels, good drainage, and a soil depth of about 10 to 12 inches. A 24 to 36 inch trough is usually the sweet spot. It gives roots enough room for lettuce, herbs, kale, or ferns, but it does not overwhelm a narrow balcony. If your railing is the only available space, choose a railing-mounted self-watering box. If you have floor space, choose a wheeled trough so you can move it for cleaning, storms, or rare sunny spells.
Why self-watering? North-facing balconies often dry out unevenly, and a reservoir keeps soil consistently moist without daily watering. Choose a model with an overflow hole and a water-level indicator. In low light, plants use less water, so do not keep the reservoir topped up blindly. Let it run low between refills, especially in cool weather.
Why light-colored? White, cream, pale gray, or soft sage reflects weak light back onto leaves and keeps roots cooler. Dark metal or black plastic can absorb heat and make soil temperatures swing. Glazed ceramic, UV-resistant resin, fiberstone, or powder-coated metal all work. Resin is lightest and easiest to move. Glazed ceramic looks polished but can be heavy. Metal is durable, but it should have drainage holes and a liner to prevent rust.
Drainage is non-negotiable. Even shade plants hate soggy roots. Make sure the planter has drainage holes, a removable plug, or a separate reservoir. Add a saucer or tray if drainage water could drip onto neighbors below. Use a lightweight potting mix, not garden soil. Mix in perlite and compost for airflow and slow feeding. Fertilize lightly, because shade plants grow slower and usually need less than sun-loving tomatoes.
What should you plant? Think leaves, not fruit. Good choices include lettuce, spinach, arugula, kale, Swiss chard, mint, parsley, chives, cilantro, lemon balm, and shade-tolerant flowers like impatiens, begonias, fuchsia, coleus, and heuchera. Avoid tomatoes, peppers, eggplant, and most fruiting vegetables, since they need much more direct sun. If you want one planter, plant a mix of cut-and-come-again greens and herbs. If you want color, choose coleus or begonias.
A strong concrete recommendation is a 30-inch white or light gray self-watering trough with casters, a water-level indicator, and at least two drainage points. Add a small trellis if you grow ivy or another trailing plant. If you can add a clip-on full-spectrum LED grow light, even six to eight hours a day will widen your plant choices. Keep it close to the leaves and use a timer. A white wall or light screen can also help bounce light around the balcony.
The best urban planter box for a north-facing balcony with little sun is ultimately the one that fits your space, holds moisture steadily, drains freely, and is easy to move. Start with a light-colored, self-watering, wheeled trough, fill it with shade-tolerant greens and herbs, and you will have a productive, low-stress urban garden even without strong sun.