For successful lavender growth in urban planter boxes, depth is crucial. Aim for a container depth of at least 12 to 16 inches (30 to 40 cm). This depth accommodates lavender's extensive, deep-rooting system, which seeks moisture and stability. While some dwarf varieties may manage in 10-inch depths, deeper is generally better for root development and plant health.
Equally important is excellent drainage. Ensure your planter has multiple drainage holes. Use a gritty, well-draining potting mix, blending standard potting soil with coarse sand, perlite, or small gravel. This mimics the lavender's preferred Mediterranean conditions—poor, dry, and alkaline soil.
Choose wide containers as lavender bushes can spread. Materials like terracotta or wood are excellent as they allow soil to breathe. Place your planter in a full-sun location, receiving at least 6-8 hours of direct sunlight daily. Water deeply but infrequently, allowing the soil to dry completely between waterings to prevent root rot.
With the right depth, soil, and care, your urban lavender will flourish, providing fragrance and beauty to your city space.