how to build a planter box for a deck

"DIY Deck Planter Box: Step-by-Step Guide"

By Ashley RodriguezJanuary 14, 2026

Build a Stylish Planter Box for Your Deck: A Comprehensive Guide

Transform your deck into a lush, green oasis with a custom-built planter box. Not only does it add aesthetic appeal, but it also provides a perfect spot for growing herbs, flowers, or vegetables. Here's a step-by-step guide to help you create a durable, attractive planter box that complements your deck.

Materials Needed

Cedar or redwood lumber (pressure-treated lumber can also be used, but it may leach chemicals into the soil)
Galvanized screws (1-1/4" and 2-1/2")
Drill and driver bits
Jigsaw or circular saw
Tape measure
Pencil
Sandpaper (120-grit)
Exterior wood glue
Stainless steel or galvanized hardware cloth (for drainage)
Landscape fabric
Potting soil
Plants or seeds

Design and Measurements

Before you start building, decide on the size and style of your planter box. Consider the space available on your deck and the types of plants you want to grow. A common size is 12" deep, 18" wide, and 6' long, but you can adjust these measurements to suit your needs.

Cut List

Piece	Dimension
Sides	18" W x 12" H x 6' L (2 pieces)
Ends	12" W x 12" H x 12" D (2 pieces)
Bottom	16" W x 11" H x 6' L

Building the Planter Box

Step 1: Cut the Pieces

Using your cut list as a guide, cut the lumber to size with a jigsaw or circular saw. Ensure the ends of the boards are square to create a sturdy box.

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Step 2: Assemble the Sides

Lay one of the side pieces flat on the ground. Apply wood glue along the 12" height of the end piece, then attach it using 1-1/4" screws. Repeat this process to create the second side assembly.

Step 3: Attach the Bottom

Place the bottom piece across the inside of the side assemblies, ensuring it's centered. Attach it using 1-1/4" screws driven up from the bottom. You may need to pre-drill holes to prevent the wood from splitting.

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Step 4: Connect the Sides and Ends

Apply glue to the 12" height of the end pieces, then attach them to the side assemblies using 2-1/2" screws. Ensure the box is square by measuring the diagonals from corner to corner – they should be equal.

Step 5: Add Drainage

Cut a piece of hardware cloth to fit the bottom of the planter box. Attach it using staples or small nails. This will allow water to drain while keeping the soil in place.

Step 6: Line the Box

Cut a piece of landscape fabric to fit the inside of the planter box. This will help prevent the soil from leaking out while allowing water and air to pass through. Place it inside the box, ensuring it covers the bottom and sides.

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Finishing Touches

Sand any rough edges or surfaces, then apply a sealant or stain to protect the wood and enhance its appearance. Allow the sealant to dry completely before filling the planter box with soil and adding your plants or seeds.

Caring for Your Planter Box

Maintain your planter box by keeping it clean, checking for and repairing any damage, and refreshing the soil as needed. With proper care, your custom-built planter box will provide years of enjoyment and beauty on your deck.

Happy building, and happy gardening!