A small planter that does the job
A planter box is a good first outdoor project because the joinery can stay simple. Straight cuts, pilot holes, exterior-rated screws, and a little care at the bottom of the box are enough.
This version makes a planter with about 22-1/2 inches of planting length, 12 inches of inside width, and about 10 inches of planting depth. It is small enough for a patio or porch and large enough to feel useful. Build it from cedar or another board you have selected for its intended outdoor use. If you plan to grow food, check the lumber and finish manufacturer's guidance before you buy.
The part that matters most is easy to miss: the planter needs a path for water to leave. A box that holds soil but traps water will stay wet where the wood and soil meet. Build the drainage into the bottom before you fill it.
What you need
Tools:
- Circular saw or miter saw
- Drill/driver and a countersink or pilot bit
- Tape measure, pencil, and speed square
- Sanding block or random-orbit sander
- Two clamps, if you have them
Materials:
- Two 1 x 6 x 8-foot boards of cedar or other lumber selected for outdoor use
- About 30 exterior-rated screws, 1-1/4 to 1-1/2 inches long
- Landscape fabric or a fine plastic mesh screen
- Exterior finish, if the product label suits your lumber and intended use
- Four small feet or scraps for raising the planter off the patio
Use straight boards. A little checking at the lumber rack saves a lot of fighting during assembly. For a broader beginner refresher on preventing common shop mistakes, see 5 common woodworking problems and how to solve them.
Cut list for the 24-inch planter
Cut these pieces from 1 x 6 stock:
| Part | Quantity | Length |
|---|---|---|
| Front and back | 4 | 24 inches |
| Ends | 4 | 12 inches |
| Bottom slats | 3 | 22-1/2 inches |
| Bottom cleats | 2 | 12 inches |
Stack two boards for each long side and two for each end. The end boards sit between the long sides, which keeps every cut square and straightforward. The three bottom slats sit on the cleats with small gaps between them.
Want a different length? Keep the same construction and change the four front-and-back pieces and the three bottom slats together. For a deeper planter, use wider side boards or add another course. Before making it much larger, think about where it will live once it is full of wet soil. A planter that is easy to build empty can be hard to move later.
Build the box
1. Make the two long sides
Lay two 24-inch boards edge to edge and clamp them together so their ends are flush. Repeat with the other pair. These are the two long sides of the planter.
2. Close the short ends
Stand the two long sides upright, 12 inches apart. At one end, fit two 12-inch boards between the long sides, stacked edge to edge and flush with the top and bottom. Drill pilot holes through each long side into the ends of both boards, then drive two screws through each long board into each end board. Repeat at the other end.
Check for square before you tighten the last screws. Measure corner to corner in both directions across the opening. When those measurements are close, the box is square enough for this project.
3. Add bottom cleats and slats
Set the box upside down. Fasten one 12-inch cleat inside each short end, about 3/4 inch above the bottom edge. These cleats support the slats.
Turn the box right-side up and rest the three 22-1/2-inch slats on the cleats. Leave an even gap between the slats. Drive one screw at each end of every slat. The gaps give water an escape route and let the bottom dry between waterings.
4. Add fabric without blocking the drain path
Cut landscape fabric or fine screen so it covers the inside bottom and rises a little way up the sides. Tack it lightly near the upper edge of the fabric. Do not stretch it tightly across the gaps, and do not cover the bottom with a solid liner that traps water.
The fabric keeps most potting mix from washing through the slats while water can still leave. Home Depot's planter guide also recommends exterior-rated screws, a fabric or screen at the bottom, and drainage holes or openings in the base. It is a useful cross-check, not a substitute for the instructions on the products you choose.
5. Sand, protect, and set the planter in place
Ease sharp corners and remove splinters. Apply a finish only after confirming it is appropriate for the lumber, location, and what you plan to grow. Follow the label for surface prep, coats, and cure time.
Add small feet or spacers underneath the planter so the bottom does not sit flat on the patio. Then place it where you want it before adding potting mix. Water the filled planter once and look underneath. You should see water leave through the bottom rather than pool in the box.
A few choices that make the build easier
Pilot holes are worth the extra minute, especially near board ends. They reduce the chance that a screw splits the wood. Exterior-rated screws are also worth buying for an outdoor project because ordinary interior screws can rust and leave marks on the wood.
Keep the design plain on the first build. If you want a more decorative plant project later, this floating plant shelf guide uses a different approach and belongs indoors. For this planter, good drainage and solid joints matter more than trim details.
Keep it in good shape
At the start and end of each growing season, empty loose debris, check the bottom slats and screw heads, and clear soil from the drainage gaps. Refresh the finish only according to its product directions. If the box stays damp or water appears underneath for a long time after watering, move it, clear the gaps, and confirm the fabric has not folded over the openings.
Wear eye protection when cutting, drilling, and sanding. Support long boards before cutting, keep your hands clear of the blade path, and let the tool reach a stop before setting it down.
The finished planter does not need fancy joinery. It needs straight cuts, a square box, and a bottom that lets water get out. Get those right and you have a small patio project that is ready for whatever you decide to plant.