Cedar Planter Box Plans: A 2-Hour Build From Fence Pickets That Lasts for Years

Store-bought planter boxes are often thin pine that rots out in a season or two. The professional’s shortcut is western red cedar — naturally rot and insect resistant, light, fragrant and free of the chemicals in pressure-treated lumber. Cedar fence pickets are the budget secret: thin, inexpensive and perfect for planters.

Think of this as your gateway project — a simple box that teaches measuring, square assembly and outdoor wood choices in a single afternoon.

Build specs

Materials

• (4) 1×6 × 6' cedar fence pickets
• (1) 2×2 × 8' cedar board for the corner posts
• 1-5/8" exterior-rated screws (coated or stainless)
• Non-woven landscape fabric and staples

Cut list

Beginner tip: check your pickets’ actual thickness before cutting the short parts. If they aren’t 5/8", adjust: short side length = 12" minus two picket thicknesses.

Step 1: Build the long walls

1. Lay two 36" pickets edge to edge with a 1/8" gap between them.
2. Place a 2×2 post flush with each end on the inside face.
3. Pre-drill and screw through the pickets into the posts — two screws per board per post.
4. Repeat for the second long wall.

The 1/8" gap lets the boards swell when wet without pushing against each other and bowing the wall.

Step 2: Connect the frame

Stand the two long walls up and screw the 10-3/4" short side pieces between them into the corner posts. Check that the box is square with a speed square, or measure the diagonals — they should be equal.

Step 3: Add the bottom and drainage

1. Flip the box upside down.
2. Lay the six bottom slats across the width, spaced about 1/4" apart.
3. Pre-drill and screw them to the bottom edges of the long walls.

The gaps are your drainage. Without them, roots rot and the wood decays far faster. For a larger planter, add a centre support under the slats.

Step 4: Line the box

Staple landscape fabric to the inside walls and bottom. It lets water drain while keeping soil from washing out through the gaps, and it keeps damp soil off the wood.

Step 5: Finishing — or not

Cedar left bare weathers to a soft silver-grey and still lasts for years. To keep the warm colour, apply an exterior penetrating oil to the outside faces only. Never finish surfaces that touch the soil in an edible garden.

For more on choosing outdoor finishes, see our outdoor wood guide.

Make it last longer

• Raise the planter on feet, bricks or blocks so the bottom can dry.
• Use stainless or coated screws — plain steel stains cedar black.
• Empty soil and store the planter dry over winter in harsh climates.

Variations

Level up: add a top cap — 1×3 cedar mitred around the rim — to hide the end grain and give a finished, furniture-like look. Our mitre joint guide shows how to get tight corners.

Pro note: build a tall, elevated version on legs for a back-friendly raised bed. Use 2×4 cedar legs and add a cross-brace; join with box joints or half-laps at the corners for a high-end look you can sell.

Want more outdoor builds? Pair this with our Adirondack chair plans.