Effective drainage is the cornerstone of successful urban container gardening. The best way to arrange drainage holes in the bottom of a planter box is to ensure multiple, evenly distributed openings. For standard rectangular or square boxes, place holes in a grid pattern, approximately 4 to 6 inches apart. For circular planters, arrange holes in concentric circles. The key is to avoid a single central hole, which can be insufficient and lead to waterlogged soil at the edges.
Always use a drill bit suitable for your planter material (ceramic, plastic, or wood) and create holes between 1/4 to 1/2 inch in diameter. Cover the holes with a permeable landscape fabric or a few pieces of broken pottery to prevent soil washout while allowing free water escape. This setup mimics natural soil conditions, preventing root rot by allowing excess water to drain freely, ensuring your plants develop a strong and healthy root system even in a confined urban space.