Absolutely, using a liner in your urban planter boxes is not only acceptable but highly recommended. A liner acts as a protective barrier between the soil and the planter's interior walls. This simple layer provides crucial benefits: it prevents soil from washing out through drainage holes, protects wood or metal planters from moisture damage and rot, helps retain soil moisture, and can make seasonal cleaning and replanting much easier.
When selecting the best liner material, consider drainage, durability, and root health. Non-woven geotextile fabric is often the top choice. This porous material allows excess water to escape freely, preventing soggy soil, while still containing the soil and letting roots breathe. For a more rigid option, consider drilling additional holes in a thin plastic container or pond liner to ensure adequate drainage. Avoid non-porous materials like solid plastic sheets or trash bags without ample perforations, as they will lead to waterlogging and root rot.
For the best results, fit the liner snugly against the planter's sides, ensuring it covers all drainage holes from the inside. Before adding soil, place a one-to-two-inch layer of coarse gravel or broken pottery shards at the bottom to further enhance drainage. Combine this with a high-quality, well-draining potting mix for a healthy environment. With the right liner setup, your urban planter boxes will be more durable, efficient, and supportive of thriving plants for seasons to come.