This is a common question for urban gardeners. The short answer is yes, lining your wooden planter boxes is highly recommended. While untreated, rot-resistant woods like cedar or redwood last longer, any wood will eventually decay from constant contact with moist soil and water. A liner acts as a protective barrier, significantly extending the life of your planter.
The primary purposes of a liner are to protect the wood from moisture and soil, and to contain the soil within the box. Without a liner, water and soil accelerate rot, and soil can wash out through gaps in the wood.
For lining, avoid non-porous plastics as they can trap water and cause root rot. Instead, use a permeable landscape fabric or a heavy-duty polypropylene fabric. These materials allow water to drain while holding the soil in. Simply staple or tack the fabric to the interior walls and bottom. Crucially, ensure your planter has adequate drainage holes at the bottom, below the liner, to let excess water escape.
An optional but beneficial step is to add a thin layer of gravel or small rocks at the bottom before adding your fabric and soil. This creates a drainage layer, further preventing waterlogging. By taking these simple steps—using a breathable liner and ensuring proper drainage—you create a healthy environment for your plants and a durable, long-lasting home for your urban garden.