How to Build & Install a Window Plant Box


Adding a window flower box to your landscape will instantly elevate that space, showcasing beautiful accents of your home. Window planters are a stunning design feature that is both beautiful and cost-effective — especially when you build window boxes yourself. Not only do they add color, but they allow you to garden according to the seasons.


Key Benefits of a Window Planter

Before you build a window planter yourself, here are some of the key benefits of adding this type of planter to your home’s landscape:

  • They provide dimension, depth, color, and texture, bringing life to any home.
  • Offers seasonal change — during the summer, you can plant brightly colored flowers, whereas in the winter, you can add evergreen shrubs, decorative branches, or vines.
  • Although they’re called ‘window planters,’ you’re most certainly not limited to the area under your windows. These planters are also great for balconies and decks, which are then hung beautifully off of a railing or fence.
  • Can be purchased or made from a wide range of materials. When making your own, you’ll want to stick to rot-resistant wood — it’s easy to work with and holds up well to the elements.



How to Build Your Own Window Planter Box

When building your own planter box, DIY projects can be highly rewarding. They’re a great experience, allowing you to increase your knowledge while saving money. There’s also the added bonus of building planters based on your personal style and taste. To make your own window flower box, feel free to get creative — here’s a classic example.

What You’ll Need

If you do not have all the tools you need, you can borrow them from a friend or family member. All of the materials can be found at your local hardware store.


  • Miter saw
  • Power drill
  • Carpenter’s square
  • Jigsaw (if making your own brackets)
  • Paintbrush



  • Wood — use cedar, cypress or redwood — you’ll need enough 1×8 material for three window length pieces, two end pieces (8” x 8”), as well as enough 1 1/4” wide wood to use as the trim (two window lengths + three pieces that are around 5 3/4” long)
  • Nails — 1 1/4” stainless steel flat head wood screws (if attaching to brick or stone, you’ll also need concrete screws)
  • Sandpaper
  • Paint and primer



  1. First, you’ll need to measure the width of the window in order to determine the length of the planter. It’s also important that the height and depth will hold enough soil to maintain the health of your plants. Within this example, the planter has a depth and height of 8-inches.
  1. The next step is to choose the type of wood you’d like to use. Cypress, redwood, and cedar are rot- and weather-resistant. Choosing softer woods, such as pine, aren’t ideal because softer woods will rot easily (unless it is pressure-treated lumber). Using the miter saw, cut the required lengths.
  1. Place the bottom of your planter on a flat working surface, hold the front board in place, drilling pilot holes every eight inches. Using these holes as your guide, insert 1 1/4-inch screws. Repeat on the back side of the planter as well. If you’d like the front piece to be on more of a slant, simply cut an angle of 15 degrees where the bottom of the front board meets your planter’s bottom board — ensuring that they’re flush.
  1. When attaching the side panels, allow for an extra 1 1/2” to overhang, allowing you to hide the cleats (see next step). Secure with screws, just as you did for the front and back.
  1. Simply fix three 8” pieces of pressure-treated 2×4 to the exterior wall, below the windowsill. To add additional support for your planter, you’ll need to provide some sort of bracket. The easiest way to create a decorative bracket, is to make a template that will accompany the shape of the siding or wall surface — then cut it out using a small jigsaw. For a simpler approach, you can also invest in some heavy-duty railing brackets — adding architectural detail.
  1. Add decorative trim to the front panel of your window box planter — once again, ensuring that each piece if flush with the top and bottom. Using the three pieces cut to a length of 5 3/4”, position them on the left, right, and center of the panel (running vertically).
  2. To finish, apply primer and paint — allowing to fully dry before sanding with a medium-grit paper.
  1. To attach to the wall, drive four screws through the back panel — four in each 2×4 cleat. Drill holes for drainage and you’re ready to plant!


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