Building your own raised beds is one of the most rewarding weekend projects for a gardener. A basic 4x8-foot cedar bed costs about $50-80 in materials and takes under two hours to assemble. This guide covers everything from choosing lumber to filling your bed with the right soil mix.
Materials List (4x8 ft, 12" tall)
- 4 boards — 2x12 cedar or untreated pine, 8 feet long
- 4 boards — 2x12 cedar or untreated pine, 4 feet long (or cut two 8-footers in half)
- 4 corner brackets — or 4x4 corner posts cut to 12 inches
- 3-inch exterior deck screws — 24 count
- Weed barrier fabric — 5x9 ft sheet (optional)
- Soil mix — approximately 32 cubic feet (1 cubic yard)
Which Wood to Use
Cedar is the gold standard — naturally rot-resistant and lasts 10-15 years without treatment.Untreated pine is the budget option at roughly half the cost but only lasts 3-5 years.Douglas fir falls in between for both cost and durability.
Avoid: Pressure-treated lumber (chemicals can leach into soil), railroad ties (creosote), and painted or stained wood.
Step-by-Step Assembly
- Level the ground. Clear sod or weeds from the footprint. The ground does not need to be perfectly flat, but remove any large bumps.
- Lay the weed barrier. Drape the fabric over the cleared area, extending 6 inches past each side. This prevents grass from growing up into your bed.
- Assemble the corners. Stand one 8-foot board and one 4-foot board at a right angle. Clamp or hold them while you drive 3 screws through the long board into the end grain of the short board. Repeat for all four corners.
- Square the frame. Measure diagonals — they should be equal. Adjust until the frame is square, then add a second screw at each corner to lock it in place.
- Position and fill. Move the completed frame to its final location. Fill with your soil mix (60% topsoil, 30% compost, 10% perlite). Water thoroughly to settle.
Tips for Longevity
- Line the inside walls with plastic sheeting to slow wood decay (leave the bottom open for drainage).
- Add corner braces or stakes if using thinner (1x) lumber.
- For beds taller than 12 inches, add a mid-height support board across the 8-foot sides to prevent bowing.
Next Steps
Once your bed is built and filled, use our free garden planner to lay out rows and calculate plant spacing. Check the spacing chart for exact plant counts, and time your planting with the seed starting guide.