How to Build a Cedar Deck Planter

Cedar is the workhorse of outdoor projects, naturally resisting rot and insects while silvering beautifully over time. A simple deck planter provides a controlled environment for your plants, keeping them off the deck boards to prevent moisture buildup and potential wood damage beneath the container. Building a custom planter allows you to match the scale of your deck perfectly. The goal is a sturdy box that drains well, holds its shape under the weight of wet soil, and looks like a purposeful addition to your outdoor space rather than an afterthought.

1. Cut All Components First. Measure and cut your 1x6 cedar boards into four side panels of equal length. Cut four 2x2 cedar posts to the height you want your planter to stand.
2. Build the Structural Frame. Attach the cedar side boards to the 2x2 corner posts using exterior-grade wood screws. Ensure the boards are flush with the outer edge of the posts.
3. Install Drainage Floor. Cut your floor boards to fit inside the base, leaving a quarter-inch gap between each board for drainage. Secure these boards to interior cleats attached to the bottom of the side panels.
4. Protect Your Deck Underneath. Screw small rubber feet or plastic spacers to the bottom of each corner post. This creates an air gap to prevent water from pooling under the box.
5. Line Interior for Soil Containment. Staple a piece of landscape fabric inside the box, covering the bottom and the sides. This holds the soil in while allowing excess water to escape through the floor gaps.
6. Seal and Cure Wood. Lightly sand any rough edges and apply an exterior-grade wood sealer or UV-protective stain. Allow the planter to cure for 24 hours before adding soil.