How to Build a Planter Box With Fence Boards | Start With The Right Cuts

Building a planter box from fence boards works best when you cut the long panels shorter than your target planter length by twice the board thickness, so the end posts bring it to final size.

Fence boards are cheap, weather-ready, and cut cleanly — the main trap is math. Measure your finished planter dimensions first, then subtract two board thicknesses from the front and back pieces so the end caps square everything up. Get that right, and the rest is cutting, fastening, and drilling drainage holes.

Measure And Cut The Frame Pieces

Start with the finished planter size you want. The end pieces get cut to the width you want the planter to be — in this example, 18 inches. The corner posts or leg pieces come from 2x4s: cut four pieces to your desired planter height, typically 16 to 20 inches for most vegetables.

A common build uses four 40-inch 2×4 leg pieces and six 3-foot fence boards for the sides. The spacers that sit between the side panels get cut to match the inside width of your box. Before cutting, lay out all your fence boards and pick the straightest ones for the visible sides.

Assemble The Four Sides

Attach the fence boards to the corner posts with galvanized screws — at least two screws per board at each post. Clamp the post to your work surface, position the first board flush with the top, and drive screws through the board into the post. Repeat for the bottom board and any middle boards you’re adding. Predrill with a pilot bit to prevent splitting, especially near the ends of fence pickets.

For a tall planter, space the middle boards evenly between the top and bottom. One fence-board tutorial assembles four leg units from 1×2 and 1×3 boards first, then attaches the front, back, and side fence boards to those corner frames. Either method works — the goal is a square, snug box with no wobble in the joints.

Build The Bottom And Add Drainage

Cut bottom boards to fit the inside dimensions of your assembled frame. If the box is 33 inches long inside, cut three or four boards that span that length and lay them across scrap blocks or support strips mounted inside the frame. Leave a 1/4- to 1/2-inch gap between each bottom board for water runoff — or go with a solid bottom and drill drainage holes instead.

Drill them before you attach the bottom boards permanently. If you’re using a solid bottom, a 2-inch hole-cutting bit can also work for larger drainage openings in a tiered design.

Line The Interior And Apply Weather Protection

Line the inside with landscape fabric or hardware cloth to slow wood rot and keep soil from washing out through the gaps. Cut the fabric to the planter’s interior dimensions, staple it in place along the top rim, then cut holes where your drainage holes sit so water can still escape. Cedar fence boards resist decay naturally, but they aren’t rot-proof — the fabric layer buys you extra years.

Sand all rough edges with 120-grit paper, then apply exterior paint, stain, or clear water sealant to the outside, inside, and bottom. Let the finish dry completely before adding soil. One upcycled build uses three coats of Spar Varathane; others prefer a simple clear sealant for a natural look. Ready-made fence planter box options can save time if you’d rather buy than build.

FAQs

What board thickness do fence pickets usually have?

Standard fence pickets are about 5/8 to 3/4 inch thick. You need to measure the actual boards you have before making the 2x-thickness subtraction for your long panel cuts.

Can I use reclaimed fence boards from an old fence?

Yes, but inspect every board for rot, dry rot, and insect damage before cutting. Discard anything soft or brittle. Keep the boards dry and store them flat while you work to prevent warping.

How long will a fence-board planter last outdoors?

Using pressure-treated posts for the corner legs extends the frame’s life significantly.