DIY Raised Garden Bed: Step-by-Step Guide

Why Cedar (or Douglas Fir)

Untreated cedar and Douglas fir naturally resist rot for 7 to 12 years without leaching anything into your soil. Skip pressure-treated pine for food gardens; while modern treatments are far safer than older CCA lumber, most food gardeners prefer to avoid them.

Redwood works if you live on the West Coast; hemlock and untreated pine are cheaper but will last only 3 to 5 years.

Materials List

Everything below is sized for a 4-by-8-foot bed, 11 inches tall (two stacked 2x6s).

• Six 8-foot 2x6 cedar boards (four full length, two cut into 4-foot ends)
• One 8-foot 4x4 cedar post cut into four 11-inch corner blocks
• About 32 exterior-rated 3-inch deck screws (star-drive hold better than Phillips)
• Landscape fabric or hardware cloth for the bottom (optional but recommended)
• Roughly 32 cubic feet of raised-bed soil blend
• Two-inch layer of straw or shredded leaves for mulch

Tools You'll Need

A basic tool kit is enough. Borrow a miter saw if you do not own one; big-box stores also cut lumber to length at the counter.

• Cordless drill and driver bit
• Miter saw or circular saw
• Tape measure and speed square
• Level
• Shovel and rake for site prep

Step 1: Pick and Prep the Site

Choose a level spot with six to eight hours of sun and easy hose access. Mark the 4-by-8-foot footprint with landscape marking paint.

If your site is lumpy, dig off the sod and rake the soil flat within about half an inch across the footprint. A level bed is critical; water pools in the low corners of a tilted bed.

Step 2: Cut the Lumber

Cut two of the 8-foot 2x6s into four 4-foot end pieces (you will use four full-length boards for the long sides and four short pieces for the ends).

Cut the 4x4 post into four 11-inch corner blocks.

Step 3: Assemble the Frame

Stand a corner block on end. Attach one 8-foot side board flush with the outer edge of the block using three screws. Repeat with a 4-foot end board on the perpendicular face of the same block.

Work your way around the rectangle attaching the first course of boards to all four corner blocks. Then stack and attach the second course on top, staggering the screws so they do not hit each other.

Check the frame is square by measuring diagonally corner to corner; both diagonals should match within a quarter inch.

Step 4: Place the Bed and Line the Bottom

Set the finished frame in position and check level. Shim low corners with a scoop of soil until level within about a quarter bubble.

If burrowing rodents are common in your area, staple half-inch hardware cloth to the bottom edge of the frame before placing. Otherwise a layer of cardboard or landscape fabric is enough to smother grass under the bed.

Step 5: Fill With the Right Soil

A 4-by-8-by-11-inch bed holds roughly 32 cubic feet of soil, or a bit over one cubic yard. Order bulk from a local landscape supply if you can; bagged soil is convenient but two to three times more expensive.

Aim for a blend of 60 percent quality topsoil, 30 percent finished compost, and 10 percent aeration material. Rake smooth and water once thoroughly to settle any air pockets, then top up any low spots.

Step 6: Plant and Mulch

Follow the spacing on your seed packets. A 4-by-8-foot bed comfortably holds two tomatoes, a row of bush beans, a block of lettuce, a couple of basil plants, and a small trellised cucumber, with room left over.

Top with two inches of straw or shredded leaves once seedlings are up. Mulch cuts watering in half and blocks most weeds.

Ongoing Maintenance

Top-dress with an inch of compost every spring and fall. Rotate crop families each year (do not plant tomatoes in the same spot two years running) to reduce pest and disease pressure.

Inspect corner joints each spring and drive in any screws that loosened over winter freeze cycles.