For an urban planter box that gets only a few hours of sun, the best strategy is to grow crops that tolerate partial shade and are harvested for their leaves, stems, or quick roots rather than large fruits. Leafy greens are the most reliable choice. Lettuce, spinach, arugula, kale, Swiss chard, and mustard greens all perform well in limited sun, especially if they receive bright morning light and protection from the hottest afternoon sun. Choose loose-leaf or compact varieties, and harvest outer leaves regularly to keep plants productive and less likely to bolt.
Herbs are another strong option. Mint, parsley, cilantro, chives, oregano, thyme, and lemon balm can grow in a few hours of sun, though mint is best kept in its own container because it spreads aggressively. Cilantro and parsley appreciate some shade, and chives are forgiving in small urban boxes. For a slightly more productive planter, add scallions, radishes, and beets grown mainly for their greens. These crops stay compact and are well suited to shallow container gardens. Carrots can work in a deeper box, but they need loose, deep soil and consistent moisture.
Avoid full-sun fruiting crops such as tomatoes, peppers, eggplant, squash, and corn unless your planter box gets more sun than expected. They may grow foliage but usually produce little fruit in low light. Instead, focus on crops that give a harvest from leaves and stems.
Use a high-quality potting mix rather than garden soil, make sure the box drains freely, and water consistently because urban planters can dry out quickly. Add a thin layer of mulch to conserve moisture, and do not crowd plants. A few hours of sun is enough for a useful, attractive planter box if you choose the right shade-tolerant edibles and keep them watered and harvested.