Build Your Own Planter Boxes for Railings for Custom Curb Appeal

Dress up your deck or porch with this DIY wooden railing planter. This one is made with two DIY window boxes.

Looking for an easy, inexpensive way to update your front porch? This custom railing planter is your summertime solution for curb appeal that lasts all year. Unlike many store-bought options, these DIY planter boxes for railings can be adjusted to fit your porch's size and style. Follow along as we show you how to build and install a simple deck rail planter.

wood porch planter box with various flowers and hanging plants
Brie Passano

How to Make Planter Boxes for Railings

Building a railing planter box is easier than you might think. In just a few hours, you'll have instant curb appeal!

Editor's Tip: Be sure to have a partner help with the installation.

Supplies Needed

  • 2 window boxes
  • Drill
  • 3/8-inch drill bit
  • Measuring tape
  • Circular saw
  • 1 x 4 x 96-inch cedar board
  • 1/2 x 1-1/2 x 96-inch cedar board
  • Wood screws

Step-by-Step Directions

Our expert tips show you how to make a railing planter from two simple window boxes.

Step 1: Build Window Boxes

Start by building two window boxes based on our how-to instructions. Sand and stain as desired before making the rest of the railing planter. Drill two or three 3/8-inch drainage holes in the bottom of each box.

Step 2: Measure and Cut

Measure the railing width and baluster width. Board sizes will differ according to your porch railing. Cut all pieces to length using a circular saw. The 1 x 4-inch board should be 1 inch longer than the length of the planters. Cut two side braces from the 1/2 x 1-1/2-inch cedar board. The side braces should be long enough to stretch across the bottom of the short ends of both planters, including the gap for the railing. Side braces should be cut at a 15-degree angle on both ends to match up with the window boxes.

Step 3: Add Bottom Brace

add cleat to back of railing planter box
Dera Burreson

The 1/2 x 1-1/2-inch cedar board will also be used to create a brace for each planter. Use it to cut two boards that are the same length as the planters. Add a brace to each planter's back and bottom edge using wood screws.

Editor's Tip: The bottom brace should be thick enough to touch the spindles attached to the railing, so the planter rests snugly against the spindles. In our case, the 1/2-inch cedar board was a perfect fit. Depending on the width of your railing, this may need to be adjusted.

Step 4: Add Top Connector

secure mailbox frame cap to top
Dera Burreson

Attach the 1 x 4-inch board to the top of one window box along the back length. Make sure all edges are aligned. Pre-drill all holes before screwing them together; do not secure with glue.

Step 5: Attach Side Braces

Dera Burreson

Pre-drill and screw a brace to either side of the window box with the top connector. Align the angled side to the angled bottom edge of the window box. One window box should now have both side braces, a back brace, and the top connector board attached.

Step 6: Install on Railing

Head to the installation site with a helper. Hold the window box with the braces on one side of the railing, sliding the side braces through the balusters. Position the second window box on the other side. Attach the second window box to the side and top braces.

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