How to Build a Raised Garden Bed

A raised garden bed extends the growing season, improves drainage, eliminates soil compaction, and keeps weeds manageable. You can build a basic 4x8 foot cedar bed in 2-3 hours for $80-$150 in materials.

Tools & Materials Checklist

• Circular saw or hand saw
• Drill/driver and 3-inch exterior screws
• Tape measure and square
• Wheelbarrow for soil
• Cardboard or newspaper for the weed barrier

Step 1: Choose the Site and Dimensions

Most vegetables need 6-8 hours of direct sun daily. Standard dimensions are 4 feet wide (reachable from both sides), 8-12 feet long, and 12 inches deep for most vegetables. Use the Raised Garden Bed Calculator to determine the exact volume of soil needed before ordering.

Step 2: Choose Lumber

Cedar and redwood are the best choices - naturally rot-resistant and safe for food crops. Expect 15-20 years of life. Douglas fir is cheaper and lasts 5-7 years untreated. Avoid pressure-treated lumber with CCA near food crops.

Step 3: Cut and Assemble the Frame

For a 4x8 foot bed using 2x12 cedar: cut two 8-foot boards and two 4-foot boards. Drill pilot holes to prevent splitting. Join corners with 3-inch exterior screws or 3/8 inch carriage bolts. Add corner posts (2x4 stakes) inside the corners for reinforcement.

Step 4: Prepare the Ground

Place the bed frame in its final location. For grass and weeds: place 6-8 layers of wet newspaper or cardboard on the ground inside the frame before filling. This smothers grass and weed seeds while decomposing into organic matter.

Step 5: Fill with Soil Mix

Mel's Mix (1/3 compost, 1/3 peat moss, 1/3 vermiculite) is the gold standard - lightweight with excellent drainage and moisture retention. A simpler option is 60% topsoil and 40% compost. Use the Raised Garden Bed Calculator to get exact cubic feet and bag counts.

Step 6: Plant and Maintain

Plant after filling - don't let soil sit bare. Water thoroughly after filling to settle the mix. Add a balanced granular fertilizer for the first season. Mulch the surface to retain moisture. Add 2-4 inches of compost each spring to replenish organic matter.

Common Mistakes to Avoid

• Building wider than 4 feet, which makes the center unreachable without stepping in and compacting the soil.
• Using pressure-treated lumber rated for ground contact near food crops instead of naturally rot-resistant cedar.
• Skipping a good soak of the cardboard weed barrier before laying it, which lets weeds punch through.
• Filling the bed and letting soil sit bare for days before planting, which lets weed seeds establish first.

Pro Tips

• Maximum width is 4 feet - wider beds require stepping in, which compacts the soil.
• Top off the bed with compost each spring - soil level drops 1-3 inches per year.
• Cedar naturally repels insects and resists rot - no sealing needed.
• Soak cardboard thoroughly before laying it.
• Order bulk soil delivery for beds larger than 4x8.

Frequently Asked Questions

What wood should I avoid for a raised garden bed? Avoid older-style pressure-treated lumber rated for ground contact if you're growing edibles; modern ACQ-treated wood is considered safer, but cedar or untreated fir remain the most common food-safe choices.

How long does a raised garden bed last? Cedar and redwood beds typically last 10–15 years untreated. Pine or fir beds last 4–7 years. Metal or composite beds can last 20+ years.

Do I need to line the bottom of a raised bed? Not usually — leaving the bottom open lets roots reach native soil and improves drainage. Add hardware cloth only if burrowing pests are a known problem in your area.