Yes—it can work very well, but a full-sun concrete patio is a tough microclimate, so you need to plan for heat, drainage, and water loss. Concrete stores and reflects heat, and the reflected light can make the area around the box even hotter than the open garden. That means an urban planter box should be sized generously, built from a material that does not overheat quickly, and set up so excess water drains freely away from both the roots and the patio surface.
Choose a box that is large enough to hold a meaningful volume of soil. Small, shallow planters dry out fast and heat up quickly. A deeper box gives roots room, buffers temperature swings, and holds moisture longer. If the planter sits directly on concrete, use feet, a wheeled base, or a gravel-and-paver gap to keep the base slightly raised. This improves airflow, reduces staining, and prevents water from pooling under the box. Make sure the drainage holes are clear and that runoff is directed to a spot where it will not damage the patio or create a slip hazard.
Soil matters in full sun. Use a quality container mix that drains well but still holds some moisture. Avoid heavy garden soil, which can become compacted and waterlogged in a container. Add a layer of mulch over the soil surface to slow evaporation and keep roots cooler. A drip irrigation system or a self-watering insert can make a big difference, especially during hot afternoons, because concrete patios can dry containers out faster than garden beds. Check moisture often at first; in peak summer, you may need to water daily or even twice on very hot, windy days.
Plant choice is the key to success. Pick full-sun, heat-tolerant, drought-resilient plants that are suited to container life. Herbs such as rosemary, thyme, lavender, and oregano often do well; so do many grasses, succulents, dwarf sunflowers, and compact flowering annuals. Avoid plants that demand constant moisture or shade. Group plants with similar water and light needs, and give taller, more sun-sensitive plants a little protection during the hottest part of the day if possible. A small trellis or taller neighboring pot can create a little filtered shade without blocking too much sun.
Also consider the reflected heat from the patio. A very dark planter in direct sun can become hot to the touch, so lighter colors, wood, composite, or insulated liners may help. Keep the planter slightly away from walls or glass that bounce extra heat. During heat waves, move lightweight boxes into part shade if needed, or use shade cloth temporarily. In winter, check drainage and protect the planter from frost if your area freezes.
With the right box, soil, watering routine, and tough plants, an urban planter box can absolutely work on a concrete patio that gets full sun. It will need more attention than a shaded garden bed, but the result can be a productive, attractive container garden that makes the concrete space feel cooler and more alive.