Does a Wooden Planter Need a Liner?

Decide what the liner is supposed to do

An open-bottom garden bed, an elevated wooden box and a decorative sleeve around a removable pot are different arrangements. A fabric that retains soil is not a waterproof barrier. A waterproof sheet can protect a sidewall but needs a planned outlet. Start with the planter maker's design and the plants' needs rather than buying a roll of plastic because the inside looks unfinished.

Give water a continuous route out

Trace water from the growing medium through the liner, through the box and clear of its support surface. Openings that do not line up can leave water trapped between layers. Keep outlets accessible and avoid pressing them flat against paving or a deck. A removable inner pot with its own drainage can simplify a decorative box, provided the outer box does not collect the runoff.

For herbs and vegetables, resolve Choosing Wood for a Raised Garden Bed independently of the liner decision.

Make seasonal inspection possible

Before filling a new box, check the outlet path with a modest amount of water and inspect underneath. Recheck during the season for roots, sediment and leaves blocking it. Never rely on a liner to justify unsuitable lumber for edible planting. If the planter sits on a deck, its saturated weight and the surface drainage are separate questions; a working drain does not demonstrate that the deck can carry the load.

Planter maker Trelush warns that waterproof liners need drainage aligned with the planter base; a liner is optional in some designs. Trelush: lining a wooden planter.

Before you finish

• Identify whether the liner retains soil or blocks water.
• Inspect the empty box before filling it.
• Keep the drainage route accessible.