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DIY Window Boxes

If you’d like to add greenery and color to your home’s exterior, try DIY window boxes . It's a great project for anyone and here we discuss the entire process from measuring to planting. Adding planters bring charm, character, and curb appeal, making your living space more attractive to visitors. Additionally, they set expectations and create value for potential buyers. On the other hand, these boxes can come in handy if you’re just looking for extra gardening space. You can plant a wide variety of flowers, herbs, and vegetables on your window sill to create a sustainable future for your family and improve your home’s air quality. That’s not all. There are also self-watering window boxes that allow you to enjoy the benefits of a mini garden without the hassle of constantly watering plants. This is especially useful when you’re far from home and can’t find anyone to tend to your flowers. In this article, we’ll discuss how to measure, make, and plant window boxes. Let’s dive right in.

DIY - Window Box Measuring

The first thing you should do is measure your windows accurately to ensure the window boxes will fit perfectly and function as intended. If the flower box is too small, your plants will be too cramped to survive. Similarly, if the box is too large, it may not fit properly onto the windowsill and thus look out of place.

How to Measure the Window's Width and Depth
Measuring tape

To measure the width of your window, extend the tape measure from the inside edge of one side to the other and record your reading. or include the trim that wraps around the window as well if you are on siding to give a more custom fitted look
Note: If your window is difficult to reach, use a ladder or ask a friend to assist you.

How to Determine the Appropriate Size for Window Boxes

Using the measurements from the window, you can calculate the right size for your window planters.

As a general rule of thumb, we recommend to make a window box that matches at least the size of the windows length and a minimum of 7" inches deep so that you have enough room for planting. This will ensure your box fits perfectly and looks proportionate to your window. A height of more than 8" is recommended for a two story home to keep the box from looking too small for the window. Finding board this tall can sometimes be challenging.

Making Window Boxes
Building flower window boxes is an amateur-friendly project. While it requires basic carpentry skills like cutting and joining lumber pieces using screws or nails, it can be an easy project if you have clear instructions and tools. You also need the patience needed to create beautiful and functional DIY window boxes that improve your home’s “wow factor.”

Lumber for the box
A saw
Outdoor paint/sealant Potting soil and plants/flowers

Using the window measurements, cut the lumber into the right-sized pieces. Assemble the box by joining its sides, bottom, and ends using screws/nails and a drill/hammer. Drill drainage holes at the bottom of the box to allow excess water to escape. Paint or seal the wood using the sealant to protect it from harsh elements of the environment. Attach the box to your window using screws/brackets. Fill the box with potting soil and your favorite plants/flowers.

Alternative Materials and Methods for Making Window Boxes
You can purchase metal window boxes or make yours from sheet metal and paint them to match your house’s exterior.

Repurposed items
like old crates or drawers are suitable for creating unique flower window boxes. Cedar wood is especially great due to it's natural resistance to bugs. Some manufacturers make cedar window boxes reinforced with composite materials for lower maintenance. PVC window boxes are a good alternative if you want to order low maintenance boxes from a manufacturer that can be painted to match your home’s exterior. For a deck or porch project instead of a window you can use flower boxes that hang on rails by hanging them from rail hooks for rail planters. If you don’t want to damage your building’s exterior, use heavy duty flower box liners or planters on your window sills or ledges without attaching them to the walls. Tips for Customizing Window Boxes to Match the Aesthetic of Your Home Here are 5 tips for customizing DIY window boxes to match the aesthetic of your house:

Your House Style Matters
If your home has a classic or rustic look, consider using wooden window boxes with a natural finish. Alternatively, if your house has a modern or contemporary style, metal or plastic window boxes with clean lines will do just fine.
Research Your Plants
Flowers like petunias and geraniums complement homes with a traditional style. The deep velvet hues of petunias make the clean white flowers of geraniums pop out. On the other hand, succulents, cacti, and other low-maintenance plants stand out in modern or contemporary homes.
Use the Right Hardware
Use brass accents and wrought iron hardware to add a timeless and elegant touch to old homes. These materials create a warm and classic experience that improves the look of traditional houses. Alternatively, use stainless steel and aluminum hardware for contemporary spaces because they have a sleek appearance that complements a modern design.
Check Your Paintwork
Ensure your colors blend seamlessly with the building’s exterior. This creates an appealing, cohesive look that ties the house’s exterior together.
Regular Maintenance
Let your flower boxes remain in optimal condition by watering the plants. You should also repaint or stain wooden window boxes approximately every 2-3 years to prevent them from deteriorating. Sealant helps keep the bugs out and a fresh coat keeps the boxes looking brand new and extends the life of the box significantly.

DIY - Installing Window Boxes

Once you’ve built your window boxes, you need to install them properly. Here’s how to go about it:
Installing Window Boxes - DIY
Tape measure
Pencil Drill Anchors Level
Measure the width of your window and the depth of the intended box to ensure it's the correct size. Consider factors like sunlight and visibility to determine the best location for the box on your window and ensure it isn’t blocking any views. Using your pencil, mark the spots where you’ll install the bracket. Drill pilot holes for the brackets, ensuring they’re slightly smaller than the anchors used to secure the brackets. Use masonry anchors to secure the brackets to brick or stone walls and the level to ensure they’re straight. Place the window box on top of the brackets and adjust them to ensure the box is stable or
directly bolt the box to your home by passing screws through the inside of the box and out the back through the siding and where the studs are located. Check the brackets or box and level regularly to ensure everything is secure and the box is safe.

Tips for Securing Window Boxes in Place

Here are a few tips for securing your DIY window boxes to ensure they’re stable:
1. Use Sturdy Brackets
Use strong brackets that can support the weight of your window boxes and plants inside. For this reason, buy brackets made of durable materials like metal or cedar with a high weight capacity. PVC window boxes can avoid using brackets altogether and can be bolted directly to a home through it's back. This is ideal when the studs are not symmetrically placed beneath a window which can cause symmetry problems when trying to use a structural bracket for support.
2. Consider Adjustable Brackets for a Railing
If you need to change the angle of your window box due to the sun’s position or any other factor, a railing box with adjustable brackets may make more sense. You can tweak these tools to your desired level.
3. Use the Right Hardware
You need the right hardware for the type of wall and brackets available. If you’re mounting a flower window box onto a brick wall, masonry anchors would be the preferred choice to wood screws. Galvanized hardware and stainless steel screws are more desirable than zinc coated due to better water resistance over time.
4. Level Goes a Long Way
A tilted box can become unstable over time and cause problems with the drainage resulting in flowers getting too much or too little water. Therefore, use a level during installation to keep the box stable and straight—improving the uniformity of your home’s exterior.

5. Use a Proper Drainage System
Ensure the window box has holes at the bottom to allow excess water to drain out and prevent waterlogging, which could kill your plants. If the holes are too small they can clog up over time and on the flip side if they are too big then soil can fall through the holes and get on the home causing staining. The ideal size drain holes are around 1/4" to 3/8" in diameter.
6. Seal/Paint It for Protection Using a sealant on wooden window boxes protects the material from moisture and stops it from rotting.
7. Check the Weight If you intend to use heavy plants in your window boxes, ensure the bracket and hardware can support the extra weight. A window box measuring 36" wide and 8" tall and deep can easily weigh around 50 pounds by the time it is completely filled with soil and plants. Make sure you hit the studs with the hardware you are using to hold the box up.
To watch a video on
how to install window boxes on siding and brick visit this link.

How to Waterproof and Seal Window Boxes

Waterproofing your window boxes helps protect the wood from water damage or rot. Here’s a step-by-step guide on how to properly waterproof and seal flower window boxes:
Sandpaper (course & fine grit)
Clean, dry rug
Wood primer
Exterior paint/stain
Waterproof sealant
Paint tray/container
Stir sticks
Step 1: Prepare the Surface
Remove any spots or uneven surfaces on the lumbar using the course-grit sandpaper. Next, use the fine-grit sandpaper to smooth out the wood surface and prepare it for the primer. Wipe the surface with a clean, dry rug to remove dust or debris.
Step 2: Apply Primer
Apply a coat of primer to the box using a paintbrush. Let the primer dry completely before applying paint.
Step 3: Paint or Stain the Box
Using a paintbrush or roller, apply a coat of paint/stain to the window box. Use light, even strokes, to avoid over-applying the paint. Let the paint or stain dry completely according to the manufacturer’s instructions. Apply additional coats until you achieve your desired finish.
Step 4: Apply Sealant
Once the paint dries, apply a coat of waterproof sealant to the box using a paintbrush. Let the sealant dry completely according to the manufacturer’s instructions. Apply additional coats until you achieve the desired level of waterproofing.
Step 5: Finish
Once the sealant dries, remove any tape used and install the box before filling it with plants.
Note: Give the paint and sealant more time to dry before watering your plants.

DIY - How to hang window boxes on a railing or balcony

You can also install or balcony to increase your gardening space and personalize your apartment’s exterior. However, the installation process is different from that of window sills. Here’s how to do it right:

Window box Brackets/hooks
Tape measure

Step 1: Measure and Mark the Location
Measure the width of the window box and the desired balcony or railing space for hanging. Use a level and pencil to mark the location for installing the bracket or hooks.
Step 2: Install the Hardware
Use a drill to attach the brackets to the railing/balcony using screws. Ensure the brackets are level and firmly attached to the railing or balcony.
Step 3: Hang the Window Box
Carefully place the box on the brackets and ensure it’s level. Adjust the position of the brackets to ensure the box is in place.
Step 4: Finish
Fill the window box with soil and your preferred plants. To watch a video of how to install flower boxes on a rail click here.

DIY - Planting Window Boxes

Planting window boxes requires you to consider how to line your box followed by plant and flower choice next, here we go:
DIY Planting Window Boxes
* potting mix
* landscape fabric
* removable inserts, pots, or liners

For planting window boxes we usually recommend a good potting mix over cheaper soils as this will deliver better nutrients to your flowers over time which is sometimes a deficit with container gardening. Potting mix is also filled with less lose dirt which results in less spill through and getting on your siding during draining. Wooden window boxes will need to be sealed on the inside to avoid water absorption of the wood. If this can't be done consider getting a removable window box liner or insert instead. Small pots can also be effective but may result in the boxes looking less full or the plants being limited in how big they can grow over time. You can also cut up a trash bag and staple it to the inside of the planter to create a water barrier that separates the soil and the flower box. Make sure to drill good drain holes throughout however. Landscape fabric, or window box filter fabric, can be cut into strips and placed over the drainage holes to act as a last second catch all that filters large clumps of dirt that might be trying to spill through the bottom. You can also tape coffee filters over the drain holes to create a strong filtering screen that cleans the water out as it passes through the drain holes.

Matt-buquoi-author-flower-window-boxesAbout the Author
Matthew Buquoi is the owner of Flower Window Boxes, Inc., which is one of the largest online
flower box companies in the United States. In addition to being the owner, he is also an expert author, and regularly writes about industry topics in the window boxes, planters, exterior shutters, and home and garden industry.