Absolutely! Using a liner inside your urban planter boxes is not just acceptable; it's highly recommended for the longevity of your planter and the health of your plants. A liner acts as a protective barrier, shielding the planter's material (especially wood) from constant moisture and soil, which prevents rot and decay. Crucially, it also helps contain the soil while still allowing for proper drainage.
So, what material is best? The ideal liner balances durability, drainage, and protection.
1. Plastic Liners (e.g., PVC, Pond Liners)
* Pros: Highly effective at retaining moisture and protecting wooden planters from rot. They are inexpensive and readily available.
* Cons: Can deteriorate with sun exposure over time. You must drill your own drainage holes to prevent waterlogged soil.
* Best For: Wooden planters where longevity is the primary concern.
2. Fabric Liners (Geotextile/Weed Barrier Fabric)
* Pros: This is often the top choice. It is water-permeable, allowing for excellent drainage and air circulation, which prevents root rot. It's also durable and resists decomposition.
* Cons: Less effective at preventing moisture from reaching the planter walls compared to solid plastic.
* Best For: Almost all situations, especially for plant health and preventing overwatering.
3. Metal Liners (Galvanized Steel)
* Pros: Offers a sleek, modern look and is very durable. It provides a strong barrier against moisture.
* Cons: Can heat up significantly in direct sun, potentially affecting plant roots. It is also more expensive and requires drainage holes to be added.
* Best For: A contemporary aesthetic where budget is less of a concern.
4. Natural Fiber Liners (Coco Coir, Burlap)
* Pros: Biodegradable and environmentally friendly. They provide good aeration and drainage.
* Cons: They will break down over time (typically in 1-2 seasons) and need to be replaced, making them less durable.
* Best For: Short-term plantings or for gardeners prioritizing organic materials.
Final Pro-Tip: Regardless of the material you choose, never let the liner block the drainage holes in your planter box. Always ensure water has a clear path to escape. For rigid liners like plastic or metal, remember to drill several holes in the bottom. Using a layer of gravel or pebbles at the base is an outdated practice that can actually worsen drainage; a good liner with proper holes is a far more effective solution.