How to Build a Raised Garden Bed Step by Step (4x8 Cedar)
Last updated: November 2026 · From the KRMPLANS team, designers of DIY building plans
Quick answer: To build a 4x8 cedar raised garden bed, cut six 2x6x8 cedar boards into four 96-inch sides and four 45-inch ends, screw them to 4x4 corner posts with 3-inch exterior screws, level the frame, staple 1/2-inch hardware cloth across the bottom, and fill it with about 1.1 cubic yards of soil. Most people finish the build in 2 to 4 hours.
This guide is for first-time builders who want one solid, square bed that lasts. It walks through a single 4x8 bed that is 11 inches tall, from the shopping list to the last wheelbarrow of soil. If you are still choosing how tall to go or which wood to use, read our raised garden bed height, depth, and wood guide first, then come back here to build.
Key Takeaways
- A 4-foot width lets you reach the center from either side; keep beds against a fence to 3 feet wide.
- Two stacked 2x6 boards make an 11-inch bed, since a 2x6 is actually 5-1/2 inches tall.
- Corner posts and exterior-rated screws keep the corners tight as the wood swells and shrinks.
- Add 1/2-inch galvanized hardware cloth under the bed if you have gophers or moles.
- A 4x8x11-inch bed holds about 29 cubic feet of soil, or roughly 1.1 cubic yards before settling.
What Materials Do You Need for a 4x8 Raised Bed?
For one 4x8 bed that is 11 inches tall, you need six cedar 2x6x8 boards, one cedar 4x4x8 (for corner posts and stakes), about 48 exterior screws, and a roll of hardware cloth. Cedar is a good choice because it is naturally rot resistant; University of Arizona Cooperative Extension notes that naturally rot-resistant lumber such as redwood or cedar may be used for raised beds.
- Lumber: 6 cedar 2x6x8, 1 cedar 4x4x8.
- Fasteners: about 48 coated or stainless 3-inch exterior screws (deck screws work well).
- Bottom barrier: 1/2-inch galvanized hardware cloth, 4 feet wide, at least 10 feet long, plus 1/2-inch staples or screws with washers.
- Optional: landscape fabric strip for the edges, cardboard to smother grass, and a bag of gravel for leveling.
- Tools: circular or miter saw, drill/driver, speed square, 4-foot level, tape measure, shovel, tin snips, and a staple gun.
What Is the Cut List for a 4x8 Cedar Bed?
The cut list for a 4x8 bed is four long sides at 96 inches, four ends at 45 inches, and four corner posts at 11 inches. The ends are 45 inches because they fit between the long sides, and two 1-1/2-inch board thicknesses plus 45 inches equals the full 48-inch width.
| Part | Qty | Material | Length | Notes |
|---|---|---|---|---|
| Long sides | 4 | Cedar 2x6 | 96 in (uncut) | Two courses per side |
| Ends | 4 | Cedar 2x6 | 45 in | Two cut from each of 2 boards |
| Corner posts | 4 | Cedar 4x4 | 11 in | Flush with top of bed |
| Mid-side stakes (optional) | 2 | Cedar 4x4 offcut | 18 to 24 in | Drive into ground at center of each long side |
| Hardware cloth | 1 piece | 1/2-in galvanized | About 4 ft x 8 ft | Turn up 2 to 4 in at edges |
Lumber dimensions are nominal, so measure your boards before cutting. Rough-sawn cedar can be a full 2 inches thick, which changes the end length to 44 inches.
How Do You Build a Raised Garden Bed Step by Step?
Build the frame on a flat surface, carry it to the site, level it, add the bottom barrier, then fill. Assembling on a driveway or patio makes it much easier to get square corners.
- Pick the spot. Most vegetables need at least 6 to 8 hours of direct sun. Keep the bed within hose reach and leave paths at least 2 feet wide, 3 feet if you use a wheelbarrow.
- Make the cuts. Cut four 45-inch ends and four 11-inch posts. Square each cut with a speed square so the corners close tight.
- Build the first end. Lay two corner posts flat, set two 45-inch boards across them flush with the post tops and outer edges, and drive two screws per board into each post. Pre-drill near board ends to prevent splitting.
- Build the second end the same way.
- Attach the long sides. Stand the ends up, set the 96-inch boards against the outside of the posts so they overlap the end boards, and screw two to three screws per board into each post.
- Check for square. Measure both diagonals. They should match within about 1/4 inch. Push the long corner in until they do.
- Level the site. Set the frame in place, mark its outline, and dig out high spots or add gravel under low corners until a level reads true on all four sides. On a slope, dig the uphill side in rather than propping up the downhill side.
- Install the hardware cloth. Flip the frame or lift one side at a time, lay the hardware cloth across the bottom, turn the edges up 2 to 4 inches inside the frame, and staple every 4 to 6 inches.
- Add stakes if needed. On 8-foot sides, drive a stake at the center of each long side inside the bed and screw the boards to it to stop bowing once the soil is in.
- Fill and water. Add soil in layers, water each layer, and top off after a week of settling.
A KRMPLANS plan such as the 8x4 cedar raised bed with A-frame trellis follows this same order and adds a trellis for cucumbers and beans, with a master cut list and cut diagrams.
Do You Need Hardware Cloth Under a Raised Bed?
You need hardware cloth under a raised bed if gophers, moles, or voles live in your area. University of Arizona Cooperative Extension advises that if pocket gophers are present, place hardware cloth in the bottom before filling with soil. Use 1/2-inch galvanized mesh, not chicken wire, which gophers can push through and which rusts quickly.
If you only fight grass and weeds, lay plain cardboard on the ground instead. It smothers sod and breaks down within a season.
How Much Soil Does a Raised Bed Need?
To find how much soil a raised bed needs, multiply length x width x depth in feet to get cubic feet, then divide by 27 to get cubic yards. For a 4x8 bed that is 11 inches deep: 8 x 4 x 0.917 = 29.3 cubic feet, divided by 27 = 1.09 cubic yards. Buy 10% to 20% extra because new soil settles.
| Bed size (L x W x H) | Cubic feet | Cubic yards | 1.5 cu ft bags |
|---|---|---|---|
| 4x8 x 6 in | 16 | 0.6 | 11 |
| 4x8 x 11 in | 29 | 1.1 | 20 |
| 4x8 x 17 in | 45 | 1.7 | 31 |
| 4x8 x 24 in | 64 | 2.4 | 43 |
Above about 1 cubic yard, bulk delivery from a landscape supplier is usually cheaper than bags.
What soil mix should you use?
A good raised bed mix is mostly quality topsoil blended with compost. University of Arizona Extension calls mineral topsoil the most desirable media for raised bed gardening and cautions against all-artificial mixes. University of Delaware Cooperative Extension's 4x8x2 bed example uses about 40 cubic feet of topsoil, 20 cubic feet of compost, and 4 cubic feet of peat moss, mixed before filling. Scaled to an 11-inch bed, that is roughly 18 cubic feet of topsoil, 9 of compost, and 2 of peat moss, perlite, or vermiculite.
Common Mistakes to Avoid
- Building wider than 4 feet, so you end up stepping into the bed and compacting the soil.
- Using interior screws or nails that rust and let the corners open within a few seasons.
- Skipping the diagonal check, which leaves a bed that will never sit flat or look square.
- Propping up the low side with loose blocks instead of digging the high side in.
- Filling with bagged potting mix only, which shrinks, dries out fast, and gets expensive.
- Using chicken wire as a gopher barrier.
DIY A-Frame Trellis Raised Garden Bed Plans: 8x4 Cedar, Cucumber PDF: instant PDF download with illustrated steps, a shopping list and cut lists.
Want something bigger or more decorative? The 10x5 cedar raised bed with corner towers uses the same post-and-board method at a larger scale. For more one-weekend ideas, see our weekend backyard projects for beginners.
Frequently Asked Questions
How long does it take to build a raised garden bed?
A single 4x8 cedar bed takes about 2 to 4 hours to build with basic tools, including cutting, assembly, and leveling. Filling it with soil adds another hour or two, depending on whether you use bags or a bulk delivery.
How many cedar boards do I need for a 4x8 raised bed?
For an 11-inch-tall 4x8 bed made with two courses of 2x6, you need six 2x6x8 cedar boards. Four stay full length for the long sides, and two are cut into four 45-inch end pieces, plus one 4x4x8 for corner posts.
How many bags of soil fill a 4x8 raised bed?
A 4x8 bed that is 11 inches deep holds about 29 cubic feet, which is about 20 bags of 1.5 cubic feet each. Buy 10% to 20% extra because the soil settles after watering.
What screws should I use for a cedar raised bed?
Use 3-inch coated exterior screws or stainless steel screws. Cedar contains natural tannins that can stain and corrode plain steel, and exterior-rated screws hold better as the wood moves with moisture.
Should I put anything in the bottom of a raised garden bed?
Put 1/2-inch galvanized hardware cloth in the bottom if you have gophers or moles. If you only need to kill grass, a layer of plain cardboard under the soil smothers the sod and breaks down within a season.
Sources
- University of Arizona Cooperative Extension: Raised Beds (PDF)
- University of Delaware Cooperative Extension: How to Construct a Raised Garden Bed (PDF)
Build Your First Bed This Weekend
One well-built 4x8 bed is the best way to learn what works in your yard. When you are ready for trellises, chevron sides, or a vine canopy, browse our raised garden bed plans with illustrated steps, shopping lists, and cut diagrams.
