How to Build a Planter Box from Cedar

Benefits of planter boxes

  • ⬥ Work well in small spaces
  • ⬥ Opportunity to beautify your walkway or porch
  • ⬥ Conserves water by keeping it close to your plants’ roots
  • ⬥ Minimizes weeds, which means healthier, more productive plants
  • ⬥ Easy to maintain
  • ⬥ Can improve fertilizer effectiveness as no other plants are soaking up the nutrients

Gather your materials

Choose your wood, selecting only wood that’s appropriate for outdoor use. Cedar is a good option as its natural oils protect the wood from rot and can act as an insect repellent. Other types of wood, such as fir can also be used

3 boards size (1” x 6” x 8’)

2 boards size (1” x 2” x 6’)

Deck screws – (1 ¼” and 2”)

Gather your tools

  • ⬥ Pencil
  • ⬥ Tape measure
  • ⬥ Table saw
  • ⬥ Carpenter’s square
  • ⬥ Power drill
  • ⬥ Countersink or 3/16-inch bit
  • ⬥ Clamps
  • ⬥ 3/8-inch spade bit (optional)

Cut your boards into the following sizes:


Six boards – 1” x 6” x 18 ¼”

Nine boards – 1” x 6” x 16 5/8”


Four boards – 1” x 2” x 14”


Two boards – 1” x 2” x 16 ½”

Three boards – 1” x 2” x 14 ¾”

How to build a planter box


Begin by forming the base.

Lay two of the 1x2x16 ½ inch boards parallel to each other, then put two of the 1x2x14 ¾ inch boards perpendicular to these boards to form a square.

Then, set three 1x6x16 5/8 inch boards across the top from one side to the other to create your base.


Now, we’re going to begin making the four walls of the box. (Each of which will be 3 boards high)

Set two 1 x 6 x 18 ¼ inch boards on their 1 inch side flat against the two longer sides of the frame of your base. Then, set the other two boards sized 1 x 6 x 16 5/8 inch on their ends, in the same manner.

These boards will be the first of the boards that will form the walls of your planter.

Use a carpenter’s square to confirm that each corner is at a 90 degree angle, then use clamps to hold the boards in position.

Now prepare the braces

Use your measuring tape and starting from the base, mark where your screws will attach your bracing to the walls. (2 screws per 6 inch wide board)

Repeat the process for the other side of the brace, then do the same for the other three braces. Then, use a 3/16 inch bit, drill pilot holes where you’ve marked each brace.

(NOTE: The boards that form the walls of the planter will be attached to these braces, eventually linking all boards together with the base.)

Build the walls

Before attaching each brace, confirm that your corner is square. Next, attach the wider side of your first brace to the flat, six inch side of your first board, using 1 ¼ inch deck screws.

Then, using the 2 inch deck screws, attach the narrower side of the brace. Make sure that the same sides of the braces face each other all the way around.

As you build up the walls, alternate the board lengths so that each side has different size boards. (i.e. you don’t have walls that are all “18 ¼ inch” or all “16 5/8 inch” in length.)

Attach the base pieces

Flip the planter over.

As you’ve not attached the center of the base yet, some boards may shift out of place; just put them back where they go.

Using 1 ¼ inch screws, attach the bottom frame to the sides of the planter along the edges on the inside.

Turn the planter back over again and then screw the bottom boards into place along the edges and into the bottom frame pieces.

Attach the bottom brace

Again, flip the planter over, face down. Using 1 ¼ inch screws, attach the final 14 ¾ inch piece of wood for bracing. Set it perpendicular to the baseboards, in the middle of the bottom of the box.

Add drainage holes

Finally, to ensure healthy plants it’s recommended that you drill holes for drainage in the bottom of the planter box.

Otherwise, create space between your plants and the bottom of the box by adding stones or rocks to help with drainage.

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