At a glance
Finished dimensions
Overall sizes
- Overall
- 30 × 12 × 11 in high
- Inside
- 28-1/2 × 10-1/2 in, about 8-3/4 in deep above the floor
- Floor
- Five slats with 1/4 in gaps
Materials
| Item | Quantity | Note |
|---|---|---|
| Cedar 1×6 (3/4 × 5-1/2 in dressed) | Three 8 ft boards | Heartwood; measure the actual thickness |
| Cedar 1×2 (3/4 × 1-1/2 in) | One 6 ft length | Cleats |
| Cedar 2×2 (1-1/2 × 1-1/2 in) | One 3 ft length | Posts |
| Exterior screws | About 40 at 1-5/8 in and 20 at 1-1/4 in | Stainless or hot-dip galvanized |
Cut list
| Part | Qty | Dimensions | Material |
|---|---|---|---|
| Long side board | 4 | 3/4 × 5-1/2 × 30 in | Cedar 1×6 |
| End board | 4 | 3/4 × 5-1/2 × 10-1/2 in | Cedar 1×6 |
| Floor slat | 5 | 3/4 × 5-1/2 × 10-1/2 in | Cedar 1×6 |
| Corner post | 4 | 1-1/2 × 1-1/2 × 8-3/4 in | Cedar 2×2 |
| Cleat | 2 | 3/4 × 1-1/2 × 28-1/2 in | Cedar 1×2 |
Tools
- A saw with a stop for repeated lengths
- Drill/driver
- Square and tape
- Clamps
The design
Each long side is two 30 in boards, one on the other, 11 in high together. The ends are two 10-1/2 in boards each, fitted between the long sides so the box is 12 in wide. Inside every corner a 1-1/2 in square post, 8-3/4 in tall, is screwed to both the side and the end; the posts stop 2-1/4 in above the bottom so they stand on the floor rather than in the drainage. Along the bottom of each long side, inside, a 3/4 × 1-1/2 in cleat runs 28-1/2 in between the ends, and five floor slats rest on the two cleats with 1/4 in gaps between them. Five slats of 5-1/2 in and four gaps of 1/4 in come to exactly the 28-1/2 in inside length.
Measure your boards before cutting. If they are not 3/4 in thick, the end boards, slats and cleat lengths change: the end boards and slats are the outside width less two board thicknesses, and the cleats the outside length less two.
Wood, fasteners and water
- Cedar heartwood. The Wood Handbook groups cedar heartwood as resistant to decay, generally satisfactory above ground. A planter full of damp soil is close to ground contact, where the Handbook points to very resistant heartwood or treated wood, so expect a cedar planter to wear out eventually and choose boards with little or no pale sapwood, which resists decay poorly in every species.
- Fasteners that will not stain. Cedar's extractives stain steel when wet; the Handbook says stainless steel or hot-dip galvanized fasteners alleviate it.
- Keep the bottom edges dry. The Handbook advises leaving space below boards exposed to weather so their bottom edges do not stay wet. Set the box on two strips or on pavers rather than straight on soil or a wet patio.
- Seal the end grain of the boards, which takes up water far faster than the faces. Finishing choices are in wood finish types.
Building it
Cleats, ends, sides and floor
Cut the parts
Cut every part in the cut list, using a stop for the repeated 10-1/2 in and 30 in lengths so they match. Lay out the long parts first on the three 1×6 boards, then the short ones.
Fix the cleats
Screw a cleat along the inside bottom edge of one lower long-side board, 3/4 in in from each end, with 1-1/4 in screws. Repeat on the other lower board.
Make the two ends
Stand two end boards edge to edge, 11 in high together. Screw a post to the inside at each end, flush with the boards' ends and top, so it stops 2-1/4 in above the bottom. Use 1-5/8 in screws, two per board per post.
Join one long side
Stack a lower and an upper long-side board, cleat inside and at the bottom, and screw them to the posts of both ends, two screws per board per post, ends flush.
Lay the floor
Lay the five slats on the fixed side's cleat and against the end boards, 1/4 in apart, sliding the end slats under the posts.
Close the box
Fit the second long side the same way, its cleat under the slats. Square the box by measuring its diagonals, then screw each slat down into both cleats with 1-1/4 in screws.
Place the planter before filling it: wet soil is heavy, and no load rating is claimed for the floor or the joints. Some builders line the sides to keep soil off the wood; if you do, keep the floor gaps open so water drains.
Safety— Cutting and handling
Cut short parts to a stop, never by holding an offcut against a blade, and follow each saw's manual. Shop practice is in woodworking safety rules and protective equipment in woodworking safety equipment.
Before filling the planter
- Boards measured, and short parts adjusted if not 3/4 in
- Heartwood chosen, with little or no sapwood
- Stainless or hot-dip galvanized screws throughout
- Diagonals equal, so the box is square
- Floor gaps open for drainage
- Box set on strips or pavers where it will stay
Why cedar, and what else lasts outside, is in outdoor woodworking projects; a bigger build in the same wood is the Adirondack chair. Board feet for the stock come from the board foot calculator.
More project plans
Looking for a larger collection of woodworking project plans?
Ted’s Woodworking is a digital plan library sold by a third party. BenchRoot did not create it and has not reviewed every plan in it, so check what it includes before you buy.
Paid link — BenchRoot may earn a commission if you purchase through this link.
Sources
A BenchRoot design; every dimension is on the drawing and in the cut list as final sizes. It was drawn and checked but not built or tested for this page, and no load or service life is claimed. Cedar boards sold for fencing are often thinner than 3/4 in; measure yours and adjust the 10-1/2 in parts if they differ. BenchRoot makes no claim about any wood, treatment or finish in contact with soil used for food plants.
- 1.
Chapter 14: Biodeterioration of Wood. USDA Forest Service, Forest Products Laboratory — Wood Handbook, FPL-GTR-282, 2021.
Used for: Decay only when wood is wetted above the fibre saturation point, as by wet ground; cedar heartwood in the resistant group, generally satisfactory above ground, very resistant heartwood for ground contact; sapwood of essentially all species low in resistance.
- 2.
Christopher G. Hunt. Wood Handbook: Wood as an Engineering Material (FPL-GTR-282), Chapter 16: Finishing Wood. USDA Forest Service, Forest Products Laboratory, 2021.
Used for: Leaving space below boards exposed to weather so the bottom edge does not stay wet; liquid water entering end grain 10 to 100 times faster than other faces, so sealing end grain is critical.
- 3.
Chapter 8: Fastenings. USDA Forest Service, Forest Products Laboratory — Wood Handbook, FPL-GTR-282, 2021.
Used for: Extractives staining steel fasteners when wet, alleviated by stainless steel, aluminum or hot-dipped galvanized fasteners.
- 4.
NIST Handbook 130 (2026), IV.B Uniform Regulation for the Method of Sale of Commodities. National Institute of Standards and Technology, 2026.
Used for: A nominal 1 × 6 dressed dry to 3/4 × 5-1/2 in and a nominal 2 × 2 to 1-1/2 × 1-1/2 in.
About this project
Written by BenchRoot Editorial. How BenchRoot sources, checks and corrects its pages is set out in the Editorial Policy. If something here is wrong or unclear, the contact page explains how to tell us.