Urban planter boxes bring greenery to city balconies, rooftops, and patios, but many gardeners wonder about the necessity of a liner. The answer isn't a simple yes or no—it depends on your specific setup and goals.
The primary purpose of a liner is to protect the planter box material from constant moisture and soil, which can cause wood to rot and metal to corrode over time. If your planter is made from untreated wood or a metal susceptible to rust, a liner is highly recommended to extend its lifespan. For durable materials like plastic, fiberglass, or properly sealed cedar, a liner might be optional.
Drainage is another critical factor. All planter boxes need drainage holes to prevent waterlogged soil and root rot. A liner can help manage this drainage, but it must itself have holes that align with the planter's drainage system. Never use a completely sealed liner, as this will drown your plants.
There are also situations where you might intentionally skip a liner. If you are using a breathable fabric pot inside a decorative planter, the fabric itself acts as a liner. Some gardeners also prefer the natural, weathered look of aging wood for certain aesthetic styles.
In summary, use a liner if your planter box is made from a material that degrades with moisture. Ensure both the liner and planter have adequate drainage. For rot-resistant planters, you can often forgo this extra layer. Understanding this balance will help your urban garden thrive for seasons to come.