Corner spaces are the most underused real estate in a garden. Fence intersections, the L-shaped area where a garage meets a house wall, the inside corner of a patio — these are dead zones in most yards. An L-shaped raised bed transforms that wasted corner into one of your most productive growing areas. By wrapping the bed around the corner, you gain planting space that a standard rectangular bed cannot reach, and you create a natural nook that is sheltered from wind on two sides.
This guide provides complete build plans for an L-shaped raised bed formed by two connected sections: one 8x4-foot rectangle and one 4x4-foot square, joined at a shared wall. Total footprint is 8 feet along one axis and 8 feet along the other (an 8x4 section plus a 4x4 section extending perpendicularly). Total planting area is 48 square feet — 32 from the rectangular section and 16 from the square section. Depth is 12 inches throughout.
The design works with either cedar or white oak. Cedar keeps the cost down and is easier to cut. White oak costs more but lasts 15 to 20 years compared to cedar's 10 to 15. Both materials use the same dimensions and assembly sequence. The cut list includes quantities for both options. For a deeper comparison, see our guide on the best wood for raised beds.
Design Overview
Imagine an L shape when viewed from above. The long arm of the L is 8 feet long and 4 feet wide. The short arm extends 4 feet from one end of the long arm, perpendicular to it, and is also 4 feet wide. The two sections share a common wall where they meet. This shared wall is structurally important — it transfers load between the two sections and keeps the L shape rigid under the lateral pressure of 48 cubic feet of soil.
The shared wall is reinforced with a doubled board and an additional center post. Without this reinforcement, the outward pressure of soil in the 8-foot section would push the shared wall into the 4-foot section. The doubled board and center post eliminate that flex completely.
The bed is 12 inches deep, built with two courses of boards and interior corner posts just like a standard rectangular bed. The difference is the corner reinforcement where the two sections meet and the additional posts along the shared wall.
Materials List
Choose cedar 2x6 boards or white oak 5/4 x 6 boards. The cut list below gives dimensions for both.
- Boards (cedar option): 8 boards of 2x6 cedar at 8 feet long
- Boards (white oak option): 8 boards of 5/4 x 6 white oak at 8 feet long
- Corner/junction posts (cedar): 2 pieces of 4x4 cedar at 4 feet long (yields 8 posts at 12 inches each)
- Corner/junction posts (white oak): 2 pieces of 4x4 white oak at 4 feet long
- Stainless steel structural screws: #10 x 3 inch — 80 screws minimum
- Stainless steel structural screws: #10 x 4 inch — 8 screws for junction reinforcement
- 120-grit sandpaper
Cut List
The L-shape is built as two connected rectangles. Section A is 8x4 feet. Section B is 4x4 feet, connected at the end of Section A.
| Part | Material | Length | Quantity | Section | Notes |
|---|---|---|---|---|---|
| Long wall — upper | 2x6 cedar or 5/4x6 oak | 96" | 2 | A | Full 8' boards, outside long walls |
| Long wall — lower | 2x6 cedar or 5/4x6 oak | 96" | 2 | A | Paired with upper long walls |
| Short end wall — upper | 2x6 cedar or 5/4x6 oak | 45" (cedar) / 46" (oak) | 1 | A | Far end of Section A (no junction) |
| Short end wall — lower | 2x6 cedar or 5/4x6 oak | 45" (cedar) / 46" (oak) | 1 | A | Paired with upper short end |
| Shared wall — upper (doubled) | 2x6 cedar or 5/4x6 oak | 45" (cedar) / 46" (oak) | 2 | A/B junction | Two boards side by side for reinforcement |
| Shared wall — lower (doubled) | 2x6 cedar or 5/4x6 oak | 45" (cedar) / 46" (oak) | 2 | A/B junction | Two boards side by side for reinforcement |
| Section B outer wall — upper | 2x6 cedar or 5/4x6 oak | 48" (cedar) / 48" (oak) | 1 | B | Extends from Section A perpendicularly |
| Section B outer wall — lower | 2x6 cedar or 5/4x6 oak | 48" (cedar) / 48" (oak) | 1 | B | Paired with upper outer wall |
| Section B far wall — upper | 2x6 cedar or 5/4x6 oak | 45" (cedar) / 46" (oak) | 1 | B | End wall of Section B |
| Section B far wall — lower | 2x6 cedar or 5/4x6 oak | 45" (cedar) / 46" (oak) | 1 | B | Paired with upper far wall |
| Section B inner wall — upper | 2x6 cedar or 5/4x6 oak | 45" (cedar) / 46" (oak) | 1 | B | Runs parallel to Section A long wall |
| Section B inner wall — lower | 2x6 cedar or 5/4x6 oak | 45" (cedar) / 46" (oak) | 1 | B | Paired with upper inner wall |
| Corner post | 4x4 cedar or white oak | 12" | 6 | All | 4 outer corners + 2 at shared wall ends |
| Junction center post | 4x4 cedar or white oak | 12" | 2 | A/B junction | Center of shared wall, both sides |
Tools Needed
- Miter saw or circular saw
- Drill/driver with appropriate drive bit
- 1/8-inch drill bit for pilot holes
- Tape measure and pencil
- Speed square
- Bar clamps — at least 4 (more is better for this build)
- Level — 4-foot level is ideal
- Safety glasses and hearing protection
- Dust mask if cutting white oak
Step-by-Step Assembly
Step 1: Cut All Pieces
Refer to the cut list and cut every piece to length before beginning assembly. Label each piece with a pencil mark — A-long, A-short, B-outer, B-far, B-inner, shared, post. This prevents confusion during assembly. Sand all cut ends.
Step 2: Build Section A (8x4 Rectangle)
Assemble Section A as a standard rectangular bed. Attach corner posts to the inside ends of both long lower boards, pre-drilling and driving two screws per post. Add the upper long boards to the same posts. Then connect the short end wall (the far end of Section A, away from the junction) by screwing it to the corner posts. Leave the junction end open for now.
Step 3: Build the Shared Wall
The shared wall is a doubled assembly. Take two boards at 45 inches (cedar) or 46 inches (oak) and place them face to face, creating a wall that is 3 inches thick (cedar) or 2 inches thick (oak). Clamp them together and drill pilot holes every 12 inches, then join them with 3-inch screws driven through one board into the other. Attach a junction center post at the midpoint of this doubled wall, and corner posts at each end.
Screw the shared wall assembly to the open end of Section A. The doubled wall sits inside the Section A frame, just as a normal end wall would. Use the 4-inch screws here — they need to pass through the side wall board, through the corner post, and bite into the doubled wall for maximum strength. Pre-drill all the way through.
Step 4: Build Section B (4x4 Square)
Section B shares one wall with Section A — the long wall of Section A that is closest to where Section B extends. So Section B has three new walls to build: the outer wall (running parallel to Section A's long wall but offset 4 feet out), the far wall (closing the end of Section B), and the inner wall (connecting back to Section A's long wall).
Attach the Section B outer wall boards to the corner post at the junction and to a new corner post at the far end. Then attach the far wall, and finally the inner wall. The inner wall of Section B connects to the long wall of Section A at one end. Use a junction post at this connection point, screwed to both the Section B inner wall and the Section A long wall.
Step 5: Check and Reinforce
Set the assembled L-bed on a flat surface and check for square. Measure the diagonals of each rectangular section — they should be equal within 1/4 inch. If not, loosen the screws at one corner, push the frame into square, and re-tighten.
Add reinforcement screws at every post from the outside of the bed walls. These long screws (3 to 4 inches) tie the wall boards to the posts and prevent joints from opening under soil pressure. Pay particular attention to the junction area — this is where the most stress occurs.
Step 6: Position and Fill
Place the L-bed in its corner location. The two outer walls follow the fence, wall, or patio edge. The inner corner of the L creates a natural access area — stand in this nook to reach into both sections.
You need approximately 48 cubic feet of soil mix (32 for Section A, 16 for Section B) — roughly 1.75 cubic yards. Order bulk delivery from a landscape supplier. For ideas on maximizing your corner space, see our article on raised bed ideas for side yards and narrow spaces.
Estimated Cost
| Item | Cedar Option | White Oak Option |
|---|---|---|
| Boards (8 boards, 8' each) | $96 – $144 | $190 – $260 |
| 4x4 posts (two 4' posts) | $24 – $36 | $50 – $80 |
| Stainless screws (2 boxes) | $30 – $45 | $30 – $45 |
| Sandpaper | $3 – $5 | $3 – $5 |
Total estimated cost: $200 – $320 depending on material choice and regional lumber pricing.
Estimated build time: 3 to 4 hours, including all cuts and the reinforced junction assembly.
Design Variations
Unequal arm lengths. The L does not have to be symmetric. You can make one arm 8 feet and the other 6 feet, or 8 and 3. Adjust the cut list accordingly — the construction method is the same regardless of arm proportions.
Different depths per section. If the corner includes a slope, you can build one section at 12 inches and the other at 18 inches (three board courses) to follow the grade. The shared wall steps from the taller section to the shorter one, with the junction post cut to the taller height.
Add a cap rail. A flat board (2x6 or 5/4 x 6) ripped to 3.5 inches wide and mitered at the inside corner makes a comfortable cap rail for sitting. This is especially nice for the inside corner of the L, where you naturally stand while tending both sections.
Frequently Asked Questions
Can I build the L-bed as two separate beds pushed together instead?
You can, but the result is weaker. Two separate beds pushed into a corner will shift over time as soil pressure and frost heave move them independently. The shared wall design locks the two sections together structurally. It also eliminates the gap between two separate beds where soil spills out and weeds grow in. A unified L-bed is stronger, cleaner, and more space-efficient than two beds sitting next to each other.
How do I handle drainage at the inside corner of the L?
Water naturally collects at inside corners. Make sure the bed sits on ground that slopes slightly away from any building foundation. Do not place landscape fabric at the inside corner — leave the soil open to the ground below so water can drain freely. If you are on heavy clay soil that drains poorly, add 2 to 3 inches of coarse gravel beneath the inside corner of the bed before filling with soil mix.
Is the junction strong enough to hold all that soil?
With the doubled shared wall, junction posts, and 4-inch reinforcement screws, the junction is actually the strongest part of the bed. A 4x8 section at 12 inches holds approximately 1,400 pounds of moist soil. The junction is designed to resist that lateral load with a wide margin of safety. The doubled wall alone provides twice the bending resistance of a single board.
Can I use pocket hole joinery instead of structural screws?
Pocket hole joints work for indoor furniture but are not ideal for outdoor raised beds. The angled screw enters end grain, which provides less holding power than face-grain screwing. Outdoor exposure and seasonal wood movement gradually loosen pocket hole joints. Structural screws driven through face grain into face grain or into the corner posts provide superior long-term holding power in an outdoor environment. Stick with the through-screwing method described in this guide.