Calculate lumber, soil volume, hardware, and total cost for building raised garden beds. Get a complete materials list with cut dimensions.
Quality materials for building durable raised garden beds.
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To calculate soil volume, multiply length x width x height in feet, then convert to cubic feet. A standard 4x8 foot bed that is 12 inches deep needs 32 cubic feet of soil (about 1.2 cubic yards). For best results, fill with a mix of 60% topsoil, 30% compost, and 10% aerating material like perlite.
Cedar is the top choice for raised beds because it's naturally rot-resistant and lasts 10-20 years without chemical treatment. Untreated cedar is food-safe and won't leach chemicals into soil. Alternatives include redwood (similar durability), modern pressure-treated lumber (safe for food gardens since 2003 when arsenic was removed), and composite lumber (longest lasting but most expensive).
Raised beds should be 6-12 inches deep for most vegetables. Shallow-rooted crops like lettuce and herbs do well in 6-8 inch beds. For tomatoes, peppers, and root vegetables, 10-12 inches is ideal. For carrots and other deep-rooted vegetables, consider 12-18 inches. Deeper beds also mean less bending for the gardener.
Lining the bottom with landscape fabric is optional but recommended in most cases. It prevents weeds from growing up through the bed while still allowing drainage. Skip fabric if you want worms and beneficial organisms to move freely between ground soil and bed soil. Always use fabric on the sides to prevent soil from washing through gaps in the boards.
Bulk delivery is significantly cheaper for larger projects. A cubic yard of bulk soil costs $30-60, while the same volume in bags (about 18-27 bags) costs $90-180. The break-even point is typically around 1 cubic yard (27 cubic feet). For one or two small beds, bags offer convenience. For three or more beds or beds over 4x4 feet, bulk delivery saves money.
Durability depends on material: Cedar and redwood last 10-20 years. Pressure-treated lumber lasts 15-20 years. Composite materials last 25+ years. Galvanized steel lasts 20-30 years. Pine or fir (untreated) lasts only 2-5 years. Using thicker boards (2 inch vs 1 inch) and adding corner brackets extends lifespan significantly.