How to Build a DIY Window Box

DIY window boxes are a quick and simple way to add curb appeal to any home or business. Plant sweet-smelling flowers to liven up your living space or add a touch of warmth to your business. And, best of all, you can do this gardening at eye level! No dirty, sore knees with this gardening project.

Follow the instructions below, to design, build, install and plant your own seasonal window box:

Designing Your Window Box

It’s important to have a clear idea of the “look” and overall design you hope to achieve BEFORE you begin building or decorating your window box.

Keep these recommendations in mind during the planning phase:

  • Be sure to choose outdoor-grade paint or stain. Choose a neutral color, a natural stain or a complementary color to your house or business. Or feel your inner designer and go for a color that contrasts beautifully.
  • If you want to add molding for a decorative flair, be sure to pick up some of that as well.
  • Think about what colors and types of flowers will complement the look and design aesthetic you hope to achieve.

Window Box Building and Installation


You’ll need quite a few tools for this project, including:

  • tape measure
  • pencil
  • carpenter’s square
  • hand or power saw
  • sandpaper
  • power drill with appropriate bits
  • safety goggles
  • screwdriver
  • hammer
  • 1 x 8 or 1 x 10 wood
  • wood glue
  • flathead screws
  • outdoor-grade paint or stain
  • paintbrushes
  • Optional supplies include the molding you might want, a miter box and saw, finishing nails and heavy-duty brackets.

Once you’ve gathered your supplies, it’s time to get to work. Follow the instructions below to build your very own window box:

  1. Measure, Mark and Cut:
    • Measure the inside width of the window. We suggest using a manufactured window box liner to hold soil and water. The width of the liner will help determine the width of your box.
    • Using a carpenter’s square, mark one board to length. Then, mark two more boards to this length plus 1 1/2 inches.
    • Cut all boards with a saw. Use sandpaper to smooth the edges.
    • Measure and cut side pieces equal to the width of the boards.
  2. Adjoin:
    • Use simple butt joints to construct the pieces into a box. Line up the bottom edge of the front of the box flush along the edge of the bottom piece.
    • Mark and drill 1/16-inch holes in the face of the front board at each end and at every 4 inches along the joint line, about 3/8-inch from the edge.
    • Put the board in place, mark the screw holes on the bottom board and drill starter holes into the edge of the board at the marks. Repeat for back and side pieces.
  3. Adhere:
    • Add glue to the front edge of the bottom board and set the front board flush into place.
    • Fortify the joint with 1 1/4-inch stainless-steel or brass flathead wood screws through the predrilled holes. Repeat for back and sides.
  4. Drill: Drill 1/2-inch-diameter drain holes every 4 inches along the center of the bottom board.
  5. Prime, Paint and Hang:
    • Prime and paint the box, inside and out, with two coats of primer and two coats of exterior-rated paint (or stain), drying between coats.
    • Attach the window box. There are a few different ways. You can drill holes into the side of the house and use deck screws to attach the box directly under the windowsill, or you might try attaching sturdy brackets to the exterior wall where the box will be installed (this may require the use of a masonry drill bit).
  6. Bonus Option:
    • For fun, flair or a more finished look, add strips of molding to the front and sides of the box.
    • Cut mitered corners at the ends and glue strips into place all around.
    • Use finishing nails about 4 inches apart to secure all strips.
  7. Planting
    • Pick plants that complement the look and color scheme of your home or business.
    • To extend the life of your window box, protect it with a manufactured window box liner to hold soil and water rather than putting them directly into the box.
    • Add soil and plants, leaving a bit of room between for them to grow.
    • Enjoy your new window box!

Your beautiful, new, DIY window boxes will draw a lot of attention to your home’s windows.

Keep them looking sharp with residential window glass repair and replacement services from your local Glass Doctor®. Schedule an appointment online or contact the Glass Doctor location nearest you to learn how Glass Doctor can fix your panes.

Speaking of summer, learn how to keep your home cool this season with energy-efficient tips from our friends, The Grounds Guys: Beat the Heat with Energy Efficient Landscaping. Like Glass Doctor, The Grounds Guys is part of the Neighborly™ family of trusted home services professionals.