Proper drainage is the unsung hero of successful urban gardening. Without it, water accumulates at the bottom of your planter box, leading to root rot, fungal diseases, and unhappy plants. Lining your box correctly is a simple yet crucial step. Here’s what you should use.
First, the primary liner for drainage is a permeable landscape fabric or a high-quality weed barrier. Place this material directly against the interior walls and bottom of your planter box. It allows excess water to escape while preventing soil from washing out and keeping the structure of the box protected from constant moisture.
Beneath this fabric, create a drainage layer. While gravel, pebbles, or broken pottery (crock) are traditional choices, they can sometimes create a "perched water table." A more modern and effective approach is to use a thinner layer of coarse materials like perlite or pumice mixed into the bottom soil, or specifically designed planter box drainage mats.
For an extra protective layer at the very bottom, some gardeners use a single sheet of newspaper or a biodegradable coffee filter before adding the landscape fabric. This helps block drainage holes from immediate soil clogging but will break down over time.
Remember, the key is to use materials that are water-permeable. Avoid lining your boxes with solid plastic, which will trap water and drown your plant's roots. By combining a landscape fabric liner with a thoughtful drainage layer, you create the ideal foundation for a thriving urban garden.