How to Build a Wooden Garden Trough | A Complete Planter Guide

A wooden garden trough is a simple rectangular planter built from treated lumber, lined to retain soil and drain water, finished to resist rot, and filled for planting.

Building your own wooden garden trough costs less than buying a pre-made planter and lets you match the exact size your space needs. The basic construction is straightforward: a rectangular frame of treated lumber, drainage holes in the base, a landscape fabric liner to keep soil in place, and an exterior finish that protects the wood for years. Here is how to build one that lasts.

What Lumber and Materials Work Best for a Garden Trough

Treated 2×6 or 2×8 lumber is the standard choice for outdoor planters in the US because it resists rot and insect damage without needing to touch the soil directly. For a medium trough, boards 5 to 10 inches wide work well.

If working with recycled pallet wood or deck boards, use anti-corrosive decking screws instead. For the liner, buy thick landscape fabric (weed barrier) or 6-mil polyethylene plastic sheeting. Finish with exterior-grade stain or paint for the wood, and coarse gravel or broken pots for the base drainage layer.

For gardeners ready to buy rather than build, our tested wooden garden trough recommendations cover durable, ready-made options that skip the carpentry.

Step-by-Step: How to Assemble the Trough Frame and Base

Cut your lumber squarely using a circular saw or mitre saw, and use a template to keep all pieces of the same length identical. Butt the end of one side board against the face of an end board, clamp them together with a right-angle clamp, and check the joint is square with a set square before driving screws through pre-drilled pilot holes. Repeat for all four corners to form the box.

Place the bottom board inside the frame so it sits flush with the bottom edges, then screw through the sides into the bottom board to secure it. Alternatively, attach gravel boards across the base to cover the frame entirely. Drill at least five drainage holes no wider than 3/4 inch across the bottom, spacing them evenly and keeping them away from the edges. For larger troughs, eight 1-inch holes work better. University of Florida extension guidelines on planter drainage confirm that hole size and spacing prevent waterlogging without weakening the structure.

Lining, Drainage Layer, and Soil Fill

Cut landscape fabric or plastic sheeting to fit the interior of the box, tack it in place with finish nails, and cut matching holes over each drainage hole. Skip this liner and soil will migrate down and clog your drainage holes within a season. Spread a layer of coarse gravel deep enough to cover the drilled holes, or use broken pots or large stones as an alternative drainage base.

Fill the trough with topsoil, mixing a slow-release fertilizer into the upper third of the soil layer. Place larger plants toward the back and follow the spacing instructions on each plant tag. Before planting, make sure the finish on the wood has dried completely—wet paint or stain can damage plant roots.

Trough-Setting and Common Mistakes to Avoid

Level the ground where the trough will sit using a six-foot bubble level. Wet soil is extremely heavy, and an unlevel trough will gradually deform and may split at the joints. Add or remove soil beneath the trough until it sits perfectly flat in both directions.

The three most frequent builder errors are easy to prevent: skipping pre-drilled pilot holes before driving screws (this splits the wood almost every time), planting before the paint or stain dries (chemicals from wet finish burn roots), and omitting the landscape fabric liner (soil clogs the drainage holes within weeks).