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DIY Cedar Planter Box Plans: A Beginner Build From Fence Pickets

Updated November 15, 2026 · 6 min read

A cedar planter box is one of the most satisfying first outdoor projects. It is simple, it looks great on a porch or balcony, and cedar fence pickets make it affordable. These plans build a box about 22 inches long, 12 inches wide and 11 inches tall, a good size for herbs, flowers or a couple of small vegetable plants.

The design uses inside corner posts, which makes it forgiving: the posts give you something solid to screw into, and the outside looks clean with no visible frame.

Why cedar fence pickets?

Cedar naturally resists rot and insects better than most common softwoods, so it holds up outdoors without chemical treatment. Fence pickets are an economical way to buy it: they are sold in the fencing aisle of most US home centers, usually about 5-1/2 inches wide and 6 feet long. Their thickness varies by brand, often around 5/8 inch, so measure your pickets before cutting and adjust the end-board length if needed.

Choose pickets with square tops (not "dog-eared") if you can, and pick the flattest, straightest boards in the pile. Avoid boards with large loose knots or long cracks.

Materials

Tools

New to tools? Our beginner woodworking tools list explains each one.

Cut list

Dimensions assume pickets about 5/8 inch thick. If yours are thicker or thinner, the end-board length is the only number that changes: it equals the box width (12 inches) minus two picket thicknesses.

Cut the long pieces first, then the shorter ones from the remaining length. Three pickets is enough with a little to spare for one mistake.

Step-by-step instructions

Step 1: Cut and sand the parts

Square one end of each picket, then cut the parts on the cut list. Sand the cut ends and any rough faces that will show. Cedar is soft, so a few passes with 80 and then 120 grit is enough. Wear a dust mask: cedar dust can irritate the nose and lungs.

Step 2: Build the two long sides

Lay two 22-inch pickets face down on a flat surface, edge to edge. Place a 2x2 corner post at each end, flush with the top and bottom edges but set in from the end by one picket thickness (about 5/8 inch). A scrap of picket held at the end makes a perfect spacer. The posts sit on the inside face of the boards, and the gap you leave is where the end boards will fit.

Pre-drill through the picket into the post, about 3/4 inch from the board edge, and drive two screws per board into each post. Pre-drilling matters with cedar; it splits easily near the ends. If you are using glue, apply a thin bead to each post first. Repeat for the second long side.

Step 3: Add the ends

Stand the two long sides up, posts facing each other. Fit an end board into the space you left at the ends: it sits between the two long side boards, against the outside face of the posts, flush with the ends of the long sides. Clamp, pre-drill and screw through the end board into the posts. Add the second end board above it, then repeat on the other end.

Check the box for square by measuring the diagonals from corner to corner. If the two numbers match, the box is square. If not, push gently on the long corners until they do.

Step 4: Install the bottom cleats

Place one 1x2 cleat along the inside bottom of each long side, between the corner posts, flush with the bottom edge. Glue and screw through the cleat into the side boards, using 1-inch screws so they do not poke through the outside face (a 3/4 inch cleat plus a 5/8 inch picket is less than 1-1/2 inches thick).

Step 5: Add the bottom slats

Measure the inside width between the long sides and cut bottom slats to that length. Lay them across the cleats. The first and last slats need a small notch at each end to fit around the corner posts: mark a 1-1/2 inch square at each corner and cut it out with two saw cuts. Leave gaps of about 1/4 inch between slats for drainage, and trim the last slat narrower if needed. You do not need to screw the slats down if they fit snugly, but one screw per end into the cleats keeps them in place.

Step 6: Line the planter

Staple landscape fabric to the inside of the box, covering the bottom and sides up to about an inch below the top. Fabric holds the soil in while letting water drain. Avoid lining it with solid plastic unless you cut drainage holes; trapped water rots the wood and drowns plants.

Step 7: Finish (optional)

You can leave cedar unfinished; it will weather to a silvery gray. To keep the warm color longer, apply an exterior penetrating stain or sealer to the outside only, following the label. If you will grow herbs or vegetables, leave the inside unfinished and rely on the liner.

Tips for a longer-lasting planter

Variations

Safety tips

More beginner builds

Enjoyed this one? Try the easy woodworking projects for beginners, build a smaller version with your kids using our simple wood projects for kids, or see why planters often appear on lists of woodworking projects that sell.

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