Short answer: for most urban planter boxes, especially long-term installations, yes—feet or a stand are strongly recommended. Hot pavement is not just a surface issue. Asphalt and concrete absorb solar heat and can stay much warmer than the air, and a planter sitting directly on that surface can take up heat through its base. That raises root-zone temperatures, speeds moisture loss, and can stress plants, particularly in shallow boxes or full sun. A stand also helps with drainage and airflow: water can escape, the base can dry, and the planter is less likely to sit in a warm, damp puddle. For wooden and composite boxes, an air gap can reduce moisture damage and extend service life; for metal or dark-colored boxes, it can reduce heat buildup. It also protects pavement from staining, rust marks, and long-term moisture.
You do not always need a tall, expensive stand. Simple pot feet, treated battens, brick spacers, or a low metal frame can be enough. Aim for at least 1–2 inches (2.5–5 cm) of clearance; 2–4 inches (5–10 cm) is often better for airflow and cleaning. Make sure the feet are load-bearing—wet soil is heavy—and spread the weight rather than concentrating it on tiny points. Keep drainage holes clear and avoid saucers that trap water and heat. On balconies or windy roofs, secure the planter and stand.
Direct contact may be acceptable for short-term seasonal displays, shaded sites, or well-insulated boxes, but monitor soil temperature and moisture closely. In hot climates or for sensitive edibles, feet or a stand are a simple, low-cost way to keep roots cooler and plants healthier.