Growing tomatoes in urban planter boxes is a fantastic way to enjoy fresh produce. For success, depth is critical. Most tomato varieties, especially vining (indeterminate) types, require a minimum soil depth of 12 to 18 inches (30-45 cm). Deeper is always better, aiming for 18-24 inches (45-60 cm) for optimal root development, moisture retention, and nutrient access.
Compact or determinate bush tomatoes can manage in 12-inch deep boxes, but they will still produce more robustly in deeper soil. The planter box itself should be 2-4 inches deeper than your soil depth to allow space for a drainage layer of gravel or broken pottery at the bottom.
Beyond depth, ensure your planter has adequate drainage holes. Use a high-quality, well-draining potting mix rich in organic matter. Consistent watering is crucial, as containers dry out faster than ground soil. With sufficient depth and proper care, your urban tomato plants will establish strong root systems and reward you with a plentiful harvest.