Choosing the right liner for your urban planter boxes is crucial for plant health and the longevity of the planter itself. While not always mandatory, a liner serves key purposes: preventing soil from washing out through drainage holes, protecting the planter's interior from moisture damage and rot, and acting as a barrier against potential contaminants from treated wood.
The most recommended and versatile liner is a permeable landscape fabric or weed barrier. It allows excess water to drain freely, preventing root rot, while keeping soil intact. Simply line the interior, cut holes for drainage, and staple or tack it in place.
For metal or highly porous planters, using a plastic sheeting (like a pond liner or heavy-duty plastic) can provide superior moisture protection. Crucially, you must puncture several drainage holes in the plastic to avoid creating a waterlogged swamp. Avoid using non-permeable materials without drainage.
Other options include lining the bottom with a layer of gravel or pebbles for basic drainage, or using natural fiber burlap, which decomposes over time. Avoid lining the sides with solid materials in wooden planters, as it can trap moisture and accelerate rot.
Ultimately, a breathable landscape fabric offers the best balance of drainage, soil retention, and protection, making it the ideal choice for most urban planter boxes.