01 of 10
Building Large Planter Boxes
Every outdoor space can be made all the more attractive with the addition of plants. However, there are many times when one can't simply dig into the dirt and plant flowers or shrubs. A solution? How about building a planter box or two? A large planter box measuring 24 by 24 by 48 inches can house some relatively large plants and is great for creating an attractive border or privacy screen for a patio or other outdoor seating area.
Continue to 2 of 10 below.
- Table saw or circular saw
- Miter saw
- 7/8-inch drill bit
- Biscuit joiner
- Staple gun
- Utility knife
- 4-by-8-foot sheet of sanded 3/4-inch plywood
- Two 8-foot 2x2 boards
- Eight 8-foot 1x4 boards
- 8-foot piece of 1-by-1-inch outside corner trim
- #10 or #20 biscuits
- 6-by-10-foot piece of 6-mil plastic sheeting
- Lampholder electrical cover with 1/2-inch conduit opening and waterproofing gasket
- 6-inch length of threaded 1/2-inch PVC conduit
- 90-degree 1/2-inch PVC elbow
- PVC glue
- Exterior wood glue
- 3/4-inch wood screws
- 2-inch wood screws
- 2-1/2-inch wood screws
- Finish nails or pneumatic finish nailer
- Painter's caulk and/or wood filler
- Primer and paint or stain and exterior polyurethane
- Silicone caulk
02 of 10
Cut the Plywood Parts
Cut the following pieces from a full sheet of 3/4-inch plywood:
Continue to 3 of 10 below.
- Two pieces at 24 by 48 inches for the sides of the planter box
- Two pieces at 22 1/2 by 23 1/4 inches for the ends of the planter box
- One piece at 22 1/2 by 48 inches for the bottom of the planter box
03 of 10
Cut Biscuit Slots
Lay out the five parts of the box on a large work surface. Make marks about every 6 inches on each piece where the edge will adjoin the neighboring piece(s). Keep in mind that some of the biscuit slots will be cut into the edge of the plywood, while others will be cut into the face:
- End pieces: Biscuit slots are cut into the edges of the plywood along the bottom and both side edges
- Bottom piece: Biscuit slots are cut into the edges of the plywood on the sides but into the face on the ends
- Side pieces: Biscuit slots are cut into the face along the bottom and both side edges
Using a biscuit joiner, cut the biscuit slots at the marks. Cut slots for either #10 or #20 biscuits.Continue to 4 of 10 below.
04 of 10
Assemble the Plywood Box
Apply a small amount of wood glue to the bottom slots of each end piece, and insert biscuits into the slots. Add a bit of glue to the corresponding slots of the bottom piece, and fit the end pieces onto the bottom piece.
Tip the unit on its side and drive some finish nails (preferably using a pneumatic finish nailer) through the plywood bottom and into the end pieces.
Add glue and biscuits to one of the side pieces, and glue the corresponding slots in the edges of the assembly that are facing upward. Fit the side onto the assembly, aligning all of the biscuits with the slots. Tap the side piece into place, then tack it with finish nails. Flip the assembly over and install the remaining side piece using the same techniques.Continue to 5 of 10 below.
05 of 10
Prepare the Trim and Bottom Supports
Cut the following pieces from 1x4 and 2x2 lumber:
- Rip four 8-foot 1x4s in half so they are approximately 1 3/4 inches wide
- Rip two 8-foot 1x4s to 2 1/4 inches wide
- Cut two pieces of 2x2 to length at 48 inches and two-piece at 21 inches for the support structure under the box
Assemble the four 2x2s to form a 24-by-48-inch frame, using 2 1/2-inch wood screws. Attach the frame to the bottom of the plywood box using glue and 2-inch screws, driving the screws through the bottom of the box and into the frame.Continue to 6 of 10 below.
06 of 10
Cut and Install the Trim
Cut and install full-width 1x4 trim along the bottom of the box so the wide face of the trim is flat against the plywood and all of the ends are mitered. Install the trim with glue and finish nails. Do the same to add 1 3/4-inch-wide trim along the top of the box so the edges of the trim are flush with the top of the box.
Trim the top edges of the box with the 2 1/4-inch-wide pieces, mitering the ends and placing the trim facedown on the top of the box and flush on the outside with the 1 3/4-inch top trim.Continue to 7 of 10 below.
07 of 10
Add the Corner Trim
Cut 1-by-1-inch outside corner trim to fit between the bottom 1x4 trim and the top trim. Attach the trim at each of the four corners with glue and finish nails to cover the exposed plywood edges of the corners.Continue to 8 of 10 below.
08 of 10
Finish the Planter Box
Fill any nail holes or blemishes with wood filler and sand the filler flush while sanding the entire project. Focus your sanding on the trim boards, making sure that any rough edges or faces are addressed.
You can stain or paint your planter box. If you use stain, you will also need to apply an exterior polyurethane, applied as directed by the manufacturer.
To paint the box, caulk all of the joints and exposed gaps to help waterproof the box. Apply two coats of quality primer to the entire unit, and follow with a few coats of paint.
Let the final coat of finish cure for at least 24 hours, or as directed.Continue to 9 of 10 below.
09 of 10
Attach the Plastic Liner
Line the interior of the box with a single piece of 6-mil plastic sheeting measuring 6 by 10 feet. Start by centering the plastic over the top of the box, then tack one edge of the plastic along one side with staples running along the top, just under the top trim. Push the plastic down into the box to cover the side, bottom, and opposite side. Staple the plastic into place along the top edge on the opposite side.
To attach the ends, fold over the plastic that bunches at the corner against the end (much like folding square corners when making a bed), and tack the flattened fold against the top of the box. Fold the opposite corner against the end of the box, and staple it in place. Repeat with the opposite side. Trim off any excess plastic with a sharp utility knife.
Be careful not to puncture the plastic when installing it, or else water may seep through the plastic and possibly damage the planter box.Continue to 10 of 10 below.
10 of 10
Install the Drain and Inside Trim
Cut a 6-inch piece of 1/2-inch threaded PVC conduit to 3 inches long. Glue the threaded piece into an electrical lampholder cover, threading it through the back side of the cover (rather than from the front).
Drill a 7/8-inch hole through the side of the plywood box at the desired height for the drain. Cut the same diameter hole through the 6-mil plastic. The lampholder cover should include a rubber gasket, but do not rely on the gasket alone. Apply a healthy bead of silicone caulk around the perimeter on both sides of the gasket, then push the conduit through the hole in the center of the gasket and finally through the hole in the plastic liner and plywood box. Screw the lampholder into place with 3/4-inch wood screws. On the outside of the box, glue a 90-degree elbow to the conduit so the bend faces downward. If desired, paint the drain parts to help hide them on the outside.
Finally, install 1 3/4-inch trim around the top inside edge of the planter box to cover the staples that hold the liner in place. Fill the nail holes and paint (or stain and polyurethane), if desired. Tip: It is a good idea to paint or stain these trim pieces before you cut and install them. They'll need a bit of touch-up after installation, but it is much easier to finish them before they are installed.