How to Build a Cedar Flower Box for Your Garden

Building a cedar flower box is a great way to add some natural beauty to your garden. Cedar is a durable and rot-resistant wood that will last for years to come.

To get started, you'll need to gather your materials, which can be found in the "Materials Needed" section. This will include cedar planks, a saw, a drill, and some screws.

Cedar is a softwood that is relatively easy to work with, making it a great choice for a DIY project like this. It's also naturally resistant to insects and decay, which means you won't have to worry about pests or rot.

The first step in building your flower box is to cut the cedar planks to the right size, as described in the "Cutting the Cedar" section. This will involve measuring and cutting four long sides and two short sides.

Take a look at this: Construction Materials List

To build a cedar flower box, you'll need some essential materials. You can use Cedar 1x4s, 1x2s, and pressure treated Pine 2x6s for this project.

Here are the specific types of wood you'll need: Cedar 1x4s, Cedar 1x2s, and pressure treated Pine 2x6s. You'll also need some additional materials like stainless steel pocket screws, wood screws, and a wood finish suitable for outdoor use.

For a more detailed breakdown of the materials needed, check out the following list:

To get started on your project, you'll need to gather the right materials. You can use grow bags or landscape fabric as the base, or opt for milk crates for a more rustic look.

Here are the specific materials you'll need:

You may also need some 2x4s, ripped offcuts from the legs, depending on your design.

Cedar is a great choice for planter boxes because it requires little maintenance and won't rot easily.

It has antifungal and antibacterial properties, thanks to the natural oils it contains, which makes it perfect for outdoor use.

You can seal your cedar planter box once a year to make it last even longer, but it won't start to break down if you don't.

Western red cedar is a particularly great option because it's also heat resistant, keeping the soil and roots of your plants cool even in scorching temperatures.

Stay away from pressure-treated lumber, as it's full of chemicals that might damage your plants.

Additional reading: Cedar Planter Box Plans Free

Cedar is a fantastic choice for planter boxes, and for good reason. It's naturally resistant to rot and won't break down easily.

One of the best things about cedar is that it requires little maintenance. You can leave it unsealed and it will still last a long time outside.

Cedar has antifungal and antibacterial properties, which makes it perfect for humid climates. This means your plants will be safe from disease and pests.

Western red cedar is a particularly great option, as it's also heat resistant. This means it won't get too hot in direct sunlight, keeping the soil and roots of your plants cool.

It's worth noting that cedar is naturally water-resistant, so you can leave it unsealed if you want. However, sealing it once a year can help it last even longer.

Here's an interesting read: Flowering Bamboo

To build a cedar flower box, you'll need some essential tools and supplies. You can use hydro poles made of red cedar if you have access to them, but if not, you can buy cedar from a lumber store.

Cedar is a great choice because it's naturally weather resistant and has a wonderful smell. It's also a good idea to use a saw mill to mill the poles into rough cut cedar planks.

Here's a list of the supplies you'll need to make a 18" by 18" by 26" tall flower box:

You'll also need some power tools to cut and assemble the pieces. A miter saw is a must-have for making precise angled cuts, and a table saw will come in handy for ripping the cedar planks to the right width.

A palm sander and some 100 grit sandpaper will help smooth out the edges and surfaces of the wood. You'll also need a pocket hole jig to create strong and invisible joints.

To drive the screws and assemble the flower box, you'll need a cordless drill and some deck screws. Outdoor wood glue will also come in handy to secure the joints and prevent water from seeping in.

Some other tools you'll need to have on hand include a measuring tape, an electric screwdriver, and a carpenter's square. Don't forget to wear safety gloves to protect your hands from splinters and cuts.

Cutting the Cedar boards to the right length is a crucial step in building a cedar flower box. This can be done with a circular saw, but using a miter saw with a stop block makes things much faster.

To assemble the panels that make up the sides of the planter boxes, you'll need four 1x4 pieces and two 1x2 pieces for each short panel. You'll need to repeat this process to make multiple panels.

Mount a ⅜-inch stacked dado blade on a table saw to cut grooves at the ends of side-panel pieces. This precise cut is essential for the project.

Cut all the Cedar pieces to length with a miter saw, except for the crosspieces for the base.

To start building your cedar flower box, you'll need to cut down all the pieces of wood to the correct size. This is a crucial step, as it will make assembly much easier.

You'll need to cut 8 pieces of wood for the bottom slats, each 12 inches long and 3 ½ inches wide. The short side rails will require 4 pieces of cedar wood, 13 ½ inches long and 1 ½ inches wide. The long side rails will need to be just as wide, but 28 inches long.

Next, you'll need to cut 22 slats, each 11 inches long and 3 ½ inches wide. These slats will provide the base for your flower box.

To cut dados and rabbets, position the saw's fence to make a full-length dado in one side of each rail, offset about ⅛ inch from the side's centerline. This will create a pleasing ¼-inch reveal between the panel pieces and rails on the planter's outside faces.

A guide block is essential for cutting precise rabbets. Clamp a 1-inch guide block to the fence and cut ⅜ x ⅜ inch rabbets on both ends.

Assembling the box is a straightforward process, but it requires attention to detail to ensure a sturdy and even structure. Use 1 ¼” screws to attach the panels to the rails.

To assemble the sides of the box, you'll need 2 rails and 3 slats for each side. Attach them to each other from the inside with 1 ¼” screws, making sure to pre-drill holes in your rails and slats to prevent the wood from splitting.

Reinforce the panels with 1 ¼” screws after assembling them, this will make the panels much sturdier and help them hold up better in the elements.

To assemble the sides of the planter box, you'll need 2 rails and 3 slats for each side. Attach them to each other from the inside with 1 ¼” screws.

Pre-drill holes in your rails and slats to prevent the wood from splitting. This is a crucial step to ensure a strong and stable assembly.

Use 1 ¼” screws to attach the rails and slats together. This will provide a sturdy base for the planter box.

For the long sides, repeat the process of attaching the rails and slats together. This will create the framework for the planter box.

Remember to check for square as you assemble the sides, just like Silva does in Example 2. This will ensure that the planter box is even and level.

Consider reading: Cedar Planter Box Ideas

As you're assembling the box, you'll need to add the bottom. This is where the 2x6 pieces come in, and it's essential to get the measurements right. Measure to confirm the length of the pieces you need.

To attach the bottom boards, you'll be using pocket screws, so drill three pocket holes into the end of each board. Make sure to get the jig settings worked out, as it can be a bit tricky.

The bottom pieces are attached to the panels with pocket screws, so use a depth stop collar on the bit to set it a little bit deeper than 1 ½”. This will ensure a secure fit.

You'll need to leave a roughly 1 ¼” gap between each of the boards to allow for drainage, so don't worry too much about getting this measurement precise.

Adding a false bottom to your planter can make a big difference in the health of your plants. Place it about 10 inches from the top of the planter, as one person did last year.

Filling the space between the false bottom and the top of the planter with soil is essential for retaining moisture. This allows the soil to stay moist, reducing the need for frequent watering.

Planting your flowers right up to the top of the planter will give them the best chance to thrive. This person filled their planter right up to the top with soil and planted their flowers, and they're doing great this year.

Watering your plants occasionally can help prevent them from drying out too quickly. Pulling the planters slightly away from the wall can also help them catch more rainwater, reducing the need for frequent watering.

For your interest: Cedar Planter Box Square

To make the planter box legs, you'll need to create a tapering jig to cut a 2.75-degree taper on the inward-facing sides of the lower legs.

This taper will start cutting 8 inches from the leg's end, and you'll need to repeat the process for the other sides and legs.

The jig will help you achieve a smooth taper, and you'll need to smooth everything out with sandpaper to get a professional finish.

As you work on the legs, keep in mind that the taper will give your planter box a unique and sturdy base.

Attach the legs to the corners of the planter boxes using construction adhesive and screws. Use 1 ¼” screws for the upper holes, but 2 ½” screws for the lower holes if the hole runs into the 2x6 bottom pieces.

Be mindful of screws underneath the holes, especially if you placed them through the corners of the panels before. Pre-drilling the holes can help prevent splitting, but it's not always necessary.

Adding trim to your planter box is a crucial step to give it a finished look.

First, sand all the corners flush to ensure the trim is seated well. I learned this the hard way, and it saved me a lot of headaches later on.

Cut the trim at a 45-degree angle on a miter saw, as it's much easier than using a circular saw. You don't want to struggle with a saw that's hard to maneuver.

Cut one end of the trim at a 45-degree angle, then flip the board around and mark the length. Cut an opposing 45-degree angle on the other end. This will give you a precise fit.

Leave the trim pieces long at first and trim them to final size based on the actual dimensions. This way, you'll avoid cutting them too short.

Use one piece as a template for the second long piece of trim. This will ensure that both pieces are the same length and fit perfectly together.

Attach the long trim pieces to the planter box with glue and 1 ½” brad nails. The 1x2 uprights are a great spot to drive in nails.

Make sure the edges of the 1x2s are flush with the outside of the panels. This will give a clean and finished look to your planter box.

Cut the short trim pieces in the same way as the long ones, and attach them to the planter box. This will complete the trim and give your planter box a professional finish.

Don't worry if there's a small gap in the miter, as it's easily fixable with some sanding. Cedar boards can be inconsistent, but a little sanding can make all the difference.

Attach the legs to the corners of the planter boxes using construction adhesive and screws. I used 1 ¼” screws for the two upper holes.

One thing to look out for is there might be a screw underneath some of the holes, depending on where you put the screws through the corners of the panels before.

Use 2 ½” screws on the lower holes since the hole runs into those 2x6 bottom pieces.

Pre-drilling the holes can help avoid splitting, like I experienced.

With the plants added, the planter boxes are complete!

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