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A Step-by-Step Guide on How to Build A Window Box Planter

A Step-by-Step Guide on How to Build A Window Box Planter - Designer Vertical Gardens

Window boxes are great for houses and apartments with balconies—as well as businesses and restaurants. Here’s a step-by-step guide to getting you started. If you've decided to freshen up the exterior of your home with window boxes, you should know the basics of window box gardening. One of the main ideas is that window boxes must match up with the length and depth of the window sill.

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An ideal window box is neither too deep nor too shallow. The perfect depth of a window planter should be determined to provide space for plant growth. It should also have proper drainage holes. This DIY guide- window box is easy to follow and require only the most basic tools to construct. Materials can be sourced from your local home improvement store, many even available in pre-cut sizes.


You have to determine your window size. This will help you to determine how much lumber you will need to purchase. 


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  • If you want your window box to run the full length of the window, add twice the length of your window box plus twice the width that you are planning to determine how much lumber you'll need for the 4 sides of the boxThe bottom will be the same length as the sides.

Similar to any garden planting, a window box comes with its own set of design & considerations. Be sure to prepare everything you need for efficient work.  More likely, you will need the following, but not limited to:

  • Cedar Boards, cut to the desired length (for example, the width of your window)
  • 2” exterior decking screws
  • Nails
  • Paints ( as the desired color)
  • Prepare your tools: Electric drill, drill bits, Saw & hammer


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Always remember to measure twice & cut once. You only get one chance at cutting before you make a mistake in your purchased woods.

  1. Measure your lumber, mark for cutting 
  2. Use your saw to cut the wood according to your desired lengths.
  3. Assemble the box:


window box
  1. Attach corners of the front board to the bottom board. Cedar planks come with one side smoother than the other.
  2. Lay another board, smooth-side-down, next to this one to form an “L” shape. Check for alignment on both ends. At the bottom of your box-front board (and, thus, through the side of the bottom board), predrill about 2” in from the board end. Put in a screw. Do the same on the other end.
  3. Drill a drainage hole
design and paint of box

If you opt to have a shiny wood finish, make sure to sand the surface of the wood with 600-grit sandpaper to remove any imperfections and to give the polyurethane/ varnish a gripping surface. Wipe the surface clean with a rag dampened and finish it with the coat of gloss polyurethane to make it shiner. 

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On the other hand, you can also paint and design as you desired. 


When it's full of plants and soil, a window box can be very heavy. The best way to mount it is to properly secure it to the exterior wall using cleats & drill it on your wall. 

window box planter

Read This Guide in building your Hanging Window Boxes using Artificial Plants

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