How to Make a Trough Planter? | Metal, Wood & Tile Options

Trough planters are made by converting galvanized metal water troughs or building wooden or tile frames, all requiring drainage holes, interior lining, and a gravel base for healthy plant growth.

A trough planter turns a simple utility item into a garden focal point. The most popular route is converting a galvanized livestock trough — you can finish drilling, lining, and filling in about an hour with a cordless drill and a cobalt bit. For those after a specific look, our cow trough planter roundup covers the best pre-made options if you’d rather skip the DIY. Wooden and tile versions take longer but offer more design flexibility. All three methods share the same fundamentals: drain the base, line the interior, and layer gravel below the soil.

Which Trough Planter Method Fits Your Garden?

Your choice depends on the look you want and the time you have. A galvanized metal trough is the fastest and most rugged — drill holes, line it, fill it, and plant within an afternoon. Wooden planters offer a warmer, classic appearance but require cutting, assembling, and finishing boards.

For all methods, the same rules apply: never skip drainage (waterlogged soil kills roots), always line the interior (gravel and fabric keep drainage holes clear), and ensure the ground or surface underneath is level before filling with soil and water.

Converting a Galvanized Metal Trough (Fastest Method)

A metal water trough becomes a planter in six straightforward steps. Use a 1/8-inch cobalt drill bit — regular bits go dull on galvanized steel almost immediately.

• Drill drainage holes: Drill about 10 holes around the perimeter near the bottom and 10 more across the base itself with a cordless drill and cobalt bit.
• Level the base: Check the ground underneath with a six-foot bubble level. Add or remove soil so the trough sits perfectly flat; an unlevel base lets the weight of wet soil deform the metal over time.
• Add a gravel layer: Fill the bottom with coarse gravel deep enough to cover the drilled holes and leave space for water to flow freely.
• Place landscape fabric: Cut thick weed barrier fabric to fit over the gravel, preventing soil from migrating down and clogging the drainage holes.
• Fill with soil: Add topsoil to the top of the trough. Mix slow-release fertilizer into the upper third of the soil as you fill, so nutrients reach roots where they’re most available.
• Plant: Place larger specimens toward the back, following the spacing on each plant’s tag for mature size.

Building a Wooden Trough Planter

A wooden planter box lets you control the dimensions and finish. Use boards 5 to 10 inches wide, 7.5mm screws for the frame, and 5cm screws for the bottom boards. Pre-drill 2.5mm pilot holes about 2.5cm from each end to prevent the wood from splitting.

Cut the lumber squarely using a circular saw or mitre saw. Butt the edges together using a right-angle clamp, check with a set square, and drive the screws. Place the bottom board inside the box and screw through the sides to secure it. Drill drain holes evenly across the bottom — at least five holes no wider than 3/4 inch. Line the interior with landscape fabric or screen, tacking it with finish nails and cutting matching holes for drainage. Sand rough edges, then apply paint or stain to the outside, inside, and bottom. Let the finish dry completely before planting or chemicals in wet paint can damage the roots.

Tile Trough Planters (Decorative Option)

Tile troughs require a wood frame as a skeleton. Cut four wood pillars to 533mm long. Pre-drill and screw them into a rectangle with wood glue for extra strength. Attach wider planks across the top with 1–2 cm gaps between them, then fix outer planks to the pillars. Press tiles firmly onto the frame and use clamps while the grout dries.

Key Mistakes That Ruin Trough Planters

Three errors cause most failures. Skipping the gravel and fabric layer is the most common — soil settles directly against the drainage holes and plugs them, waterlogging the roots. Failing to level the base before filling lets the weight of soil bend metal troughs out of shape. Using a standard drill bit on galvanized steel wastes time and money; only a hardened cobalt bit cuts through without dulling. For wooden planters, not pre-drilling pilot holes splits the wood at the screw entry point.