Yes—if you plan to eat the herbs, treat the planter box as part of your edible garden. The box does not necessarily need a specific “food-safe” certification, but the materials, finishes, liner, and soil should be safe for growing edible plants. Herbs can absorb contaminants through their roots, and their leaves can trap urban dust and pollution, so choosing the right container is more than a cosmetic decision.
A good rule is to use materials intended for edible gardening or direct food contact whenever possible. Food-grade HDPE plastic, polypropylene, untreated cedar or pine, stainless steel, and lead-free glazed ceramic are generally sensible choices. Avoid old railroad ties, creosote-treated wood, CCA pressure-treated timber, unknown reclaimed wood, PVC, old tires, chipped lead-glazed pottery, and painted surfaces that may contain lead or other harmful substances. If you use galvanized metal, line it with food-grade plastic and ensure drainage, because zinc can leach into acidic soil over time. Copper containers should generally be avoided for edible plants because copper can be toxic to roots.
Finishes matter too. Do not use ordinary stains, varnishes, or paints on the inside of a planter box unless the product is clearly labeled safe for edible gardens and has fully cured. A food-grade liner can help separate soil from a decorative container, but it must not block drainage. Drill drainage holes if needed, use a saucer that does not let water sit against the soil, and clean containers with mild soap and water rather than harsh chemicals.
In urban settings, soil choice is just as important as the box itself. Use clean potting mix rather than digging soil from roadsides, old buildings, or unknown sites. If you want to use local soil, have it tested for lead and other contaminants first. Place planter boxes away from heavy traffic, building exhaust, and places where roof runoff or paint dust may fall into them. Mulch the soil surface to reduce dust, and wash herbs before eating.
So, do urban planter boxes need to be food-safe if you are growing herbs? For herbs you intend to eat, yes in practice: choose non-leaching, food-safe materials, avoid risky treated or unknown materials, provide good drainage, and use clean soil. If the herbs are purely ornamental and will never be eaten, the safety standard can be lower—but for edible herbs, it is worth being careful.