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How To Make a Cedar Planter Box

Tom Silva and Kevin O’Connor work together to build a freestanding DIY cedar planter box that will dress up any patio or deck.

A lush wood planter brimming with vines and flowers offers a restful, welcome sight in outdoor spaces. Here’s one you can make yourself out of durable, rot-resistant western red cedar that will last a lifetime.

This Old House general contractor Tom Silva designed it to look like a piece of furniture, with four tapered legs that allow the underside to dry out and the deck or patio underneath to be cleaned. He also provided an air space between the wood and the soil by putting the potting mix in two milk crates lined with fabric grow bags. Water drains freely through the bags, the crates, and the planter’s open bottom without soaking the sides.

For ease of construction, Tom attached the planter’s sides, legs, and top with stainless steel pocket screws. These hidden fasteners sit inside low-angled holes bored with a special jig and bit. Once the holes are made, assembly is a snap.

Cedar Planter Box Plans

Cedar Planter Box Plans Diagram Gregory Nemec

For the Cut List, scroll to the bottom of the article.

How to Make a Cedar Planter Box

1. Prep the Pieces

Man Mounts Dado Blade On Table Saw To Make Cedar Planter Box Anthony Tieuli
  • Using a miter saw, cut all the pieces to length, except the crosspieces for the base, following the cut list.
  • Mount a 3⁄8-inch stacked dado blade on a table saw, as shown, to cut dadoes (grooves) in the planter’s rails and rabbets (notches) in the ends of side-panel pieces. Set the blade to make 3⁄8-inch-deep cuts.

2. Cut the Dadoes and Rabbets

Man Cuts Dadoes And Rabbets To Make Cedar Planter Box Anthony Tieuli
  • Position the fence to make a dado in one side of each rail that is offset 1⁄8 inch from the side’s centerline; cut the dado along the full length of each rail.
  • For the rabbets, clamp a 1 guide block to the fence, as shown, and set the blade height to cut a 3⁄8-by-3⁄8-inch rabbet into both ends of each panel piece.

3. How They Fit Together

Rabbet On End Of Each Panel Piece Slips Into Dadoes Of Cedar Planter Box Anthony Tieuli
  • The rabbet on the end of each panel piece slips into the dadoes on the top and bottom rails, as shown. The offset dado makes an eye-pleasing 1⁄4-inch reveal between the panel pieces and the rails on the planter’s outside faces.

4. Taper the Legs

Man Tapers Legs Of Cedar Planter Box Anthony Tieuli
  • Replace the dado blade with a saw blade. Rip the rails to width and rip each 4x4 down to 2 1⁄4 inches square.
  • Next, set or make a tapering jig to cut a 2.75-degree taper on the inward-facing sides of the lower legs. Mount a leg in the jig, and set the saw fence so the blade starts cutting the taper 8 inches from the leg’s end, as shown.
  • Rotate the leg a quarter turn, put it back in the jig, and cut the second taper. Repeat with the other three legs.
  • Use sandpaper to smooth all the cut sides and ease the sharp edges.

How to Make Taper Cuts

  • Cutting a taper is best done on a table saw using a tapering jig, which angles the stock away from the fence. You can buy an adjustable tapering jig, or follow Tom’s lead and construct a custom jig out of scrap wood (overview).
  • To use his jig, Tom butts one end of a leg against the jig’s hook, slides the leg under the 1x3, and holds the leg in place by driving a couple of screws horizontally through the 1x2.

5. Shape the Legs

Man Shapes Wooden Leg On Router Table For Cedar Planter Box Anthony Tieuli
  • Chuck a 1-inch-radius roundover bit into a router mounted to a router table.
  • Turn on the router and feed each leg’s untapered edge past the spinning bit over the leg’s entire length.
  • Use a block plane to make a slight chamfer in the long outside edges of the panel pieces.

6. Drill Pocket Holes

Man Drills Pocket Holes For Cedar Planter Box Anthony Tieuli
  • Using a pocket-hole jig and bit, drill evenly spaced holes through the inside faces (not the faces with the 1⁄4-inch reveal) at both ends of the rails, as shown.
  • Next, drill pocket holes into the inside faces of the top rails, down toward the undadoed sides. (See the pocket-hole placement in Step 11.)

How to Use a Pocket-Hole Jig

  • Set the depth. Adjust the jig and the stop collar on the bit to match the thickness of the stock. Both settings are shown on the jig.
  • Note the grain direction. Make sure that the wood grain of the piece receiving the screws runs perpendicular to the screw. Screws driven into end grain won’t hold.
  • Adjust the drill clutch. Set the drill torque so that the pocket-screw heads sit tight to the bottom of the pocket without stripping the hole.
  • Double-check the screw length. The screw tip should not exit the wood.

7. Attach the Top Rails

Man Attaches Top Rails Of Cedar Planter Box Anthony Tieuli
  • Clamp a leg, rounded edge down, to the workbench.
  • Place a top rail on 1 spacer blocks with the pocket holes facing up.
  • Line up the rail’s undadoed side with the top of the leg and butt the rail end tight against the leg.
  • Drive pocket screws into the leg, as shown.

8. Attach the Bottom Rail

Man Tape Measures Bottom Rail Of Cedar Planter Box Anthony Tieuli
  • Rest the rail, pocket holes up, on 1 spacers and insert the ends of a panel piece snugly into the dadoes of both rails.
  • Push all three pieces against the leg, then slide the bottom rail away from the top one by 1⁄8 inch, as shown. That allows the rails to swell when wet.
  • Pocket-screw the bottom rail to the leg.

9. Assemble One Side

Man Slides Remaining Panel pieces Into Rails’ Dadoes Of Cedar Planter Box Anthony Tieuli
  • Slide the remaining panel pieces into the rails’ dadoes, leaving the 1⁄4-inch reveal on the outside.
  • Clamp another leg to the workbench, as in Step 7. Rest the rails on 1x spacer blocks so the top rail is flush with the leg’s top, leaving a 1⁄8-inch gap between the rails and panel pieces.
  • Pocket-screw both rails to the leg.

10. Assemble the Box

Man Assembles Cedar Planter Box Anthony Tieuli
  • Repeat Steps 7, 8, and 9 to make two more sides. Attach the rails to the legs, as shown.
  • Follow a different order when making the last side: Screw the top rail to both legs, fit the panel pieces into the top rail’s dado, then slip the bottom rail over the panel pieces’ ends. Fasten that rail to the legs, leaving a 1⁄8-inch gap.

11. Fit the Top

Man Fits Top Of Cedar Planter Box Anthony Tieuli
  • Miter the 5⁄4x6 stock to the lengths specified on the cut list.
  • Drill pocket holes in the ends of the long pieces, then glue the miter joint and clamp it so the jaws straddle the joint. That will keep the faces flush as you drive the pocket screws through the miter. Wipe up excess glue with a damp rag.
  • Now mark the 1-inch overhang on each corner of the top, and place the box upside down on those marks. Pocket-screw the top rail to the top, as shown. The top acts like the face frame on a cabinet, stiffening the box and preventing it from racking.

12. Sand the Top

Man Sands Top Of Cedar Planter Box Anthony Tieuli
  • When the glue dries, in about an hour, fit an orbital sander with 220-grit sandpaper and smooth the top, as shown. Also use the sander to ease the top’s edges and corners, and erase any glue residue in the joints. Follow up with 320 grit to eliminate scratches.

13. Construct the Base

Man Constructs Base Of Cedar Planter Box Anthony Tieuli
  • Cut four identical crosspieces from the 4x4 rip cuts and two identical stringers from the dadoed 5⁄4x6 stock.
  • Space the crosspieces to support the crates. Position one side of each crosspiece flush with each stringer’s undadoed side, and fasten the pieces in a ladder-like frame with 2 1⁄2-inch deck screws, as shown.

14. Install the Base

Man Installs Base Of Cedar Planter Box Anthony Tieuli
  • Slide the base, dadoed-edge down, between the bottom rails, as shown.
  • Set the lower edge of the stringers 3 inches above the lower edge of the bottom rails, then fasten the stringers to those rails with 1 1⁄4-inch wood screws.

15. Fit the Milk Crates

Man Fits Milk Crates Into Freestanding Cedar Planter Box Anthony Tieuli
  • Put the grow bags into the milk crates and set the crates on the planter’s base, as shown.
  • Place the planter in its final location and fill with soil and plants. To protect the wood from the sun and weather, apply a penetrating oil finish made for decks.

Cut List for Making a Cedar Planter Box

5/4x6s (mitered long points)
2 at 38 5/16 inches
2 at 24 1/4 inches

4x4s ripped down to 2 1/4 inches square
4 at 28 3/4 inches

5/4x6s ripped to 2 3/4 inches wide
2 at 17 5/8 inches
2 at 31 1/16 inches

5/4x6s ripped to 5 inches wide
2 at 17 5/8 inches
2 at 31 1/16 inches

2 at 31 inches

2x4s, ripped offcuts from legs
4 at 16 3/4 inches

28 at 13 inches