Calculate soil, wood, and materials needed for your raised garden bed project
Raised garden beds offer superior drainage, better soil control, and easier access for gardening. The key to a successful raised bed is proper planning of dimensions and materials. Standard raised beds are typically 4 feet wide (allowing easy reach from both sides), 8-12 feet long, and 12-24 inches deep. The depth depends on what you're growing - shallow-rooted crops like lettuce need 6-8 inches, while deep-rooted vegetables like tomatoes thrive with 12-18 inches of soil depth.
| Wood Type | Lifespan | Cost | Best For |
|---|---|---|---|
| Cedar | 15-20 years | $$$ High | Long-term gardens, naturally rot-resistant |
| Pine (Untreated) | 5-7 years | $ Low | Budget builds, temporary beds |
| Composite | 25+ years | $$$$ Very High | Permanent installations, low maintenance |
| Redwood | 15-20 years | $$$ High | Premium builds, naturally resistant |
Different plants need different soil depths. Leafy greens and herbs thrive in 6-8 inches, root vegetables like carrots need 12 inches, and tomatoes or peppers prefer 18-24 inches. Consider your primary crops when determining bed depth.
Soil naturally compacts and settles over time, especially after watering. Plan for 10-15% settling by slightly overfilling your bed initially or keeping extra soil on hand for topping up throughout the season.
Raised beds naturally drain better than ground-level gardens, but proper drainage is still crucial. Consider adding a layer of gravel at the bottom for heavy clay soils, or use a well-draining soil mix with compost and perlite.
Place beds where they'll receive 6-8 hours of sunlight daily. Orient long beds north-south for even sun exposure. Ensure easy access to water sources and leave 2-3 feet between beds for comfortable walking and maintenance.
Level the ground and remove grass or weeds. Lay down landscape fabric or cardboard to suppress weeds. Ensure the site has good drainage and receives adequate sunlight for your planned crops.
Cut boards to length and assemble corners using galvanized screws or corner brackets. For beds deeper than 12 inches, stack boards and secure them together. Add corner posts for extra stability on larger beds.
Use a quality raised bed soil mix: 60% topsoil, 30% compost, and 10% perlite or vermiculite. This provides good drainage, nutrients, and aeration. Fill to within 2 inches of the top to prevent soil spillover when watering.
Install drip irrigation or soaker hoses before planting. Add a 2-3 inch layer of mulch to retain moisture and suppress weeds. Consider adding trellises or hoops for vertical growing and season extension.
Example: 8ft × 4ft × 1ft Cedar Raised Bed
Soil Volume: 8 × 4 × 1 = 32 cubic feet (1.19 cubic yards)
Soil Bags: 32 ÷ 1.5 = 22 bags (1.5 cu ft bags)
Wood Perimeter: 2 × (8 + 4) = 24 feet
Wood Boards: 24 ÷ 8 = 3 boards (8ft cedar boards)
Estimated Cost: (3 × $15) + (22 × $5) = $45 + $110 = $155
This creates a standard 4×8 raised bed perfect for vegetable gardening, with enough depth for most crops and easy access from both sides.