Plant Care
How to Build a Raised Garden Bed: Step-by-Step Construction Guide
Last updated: November 14, 2025
Learn to build a durable raised garden bed with our detailed construction guide covering materials, tools, and assembly techniques.
— Image © PlantReference.org 2026
TL;DR
Building a raised garden bed requires cedar or composite lumber, basic tools, and proper ground preparation. Most beginners can complete a 4x8 foot bed in 2-3 hours using 2x10 or 2x12 boards with galvanized screws and metal corner brackets. Key success factors include level ground preparation, proper drainage, and using rot-resistant materials for 15-20 year lifespan.
Frequently Asked Questions
What is the best wood for building raised garden beds?
Cedar ranks as the top choice for raised bed construction due to natural rot resistance, chemical-free safety for food crops, and 15-20 year lifespan. While more expensive than pine, cedar eliminates replacement costs and chemical concerns. Redwood offers superior longevity but costs significantly more in most markets. Composite lumber provides the longest lifespan at premium pricing but lacks natural wood aesthetics many gardeners prefer.
How deep should a raised garden bed be for vegetables?
Most vegetables thrive in 10-12 inches (25-30 cm) deep beds using standard 2x10 or 2x12 lumber. Root vegetables like carrots and parsnips need 14-18 inches (35-45 cm) minimum depth for proper development. Shallow-rooted crops including lettuce, herbs, and radishes grow successfully in beds as shallow as 6-8 inches (15-20 cm). Deeper beds provide better drainage and root expansion space but require more soil volume and higher initial costs.
Do I need to put anything on the bottom of a raised garden bed?
Never use solid barriers like plastic sheeting which prevent drainage and create anaerobic soil conditions harmful to plant roots. Cardboard works excellently as a biodegradable weed barrier that decomposes within 6-8 months while blocking grass and weeds initially. Hardware cloth (1/4-inch mesh) protects from burrowing pests in areas with vole or gopher problems. Most beds require no bottom treatment when placed on natural soil with adequate drainage.
How much soil do I need to fill a 4x8 raised garden bed?
A 4x8 foot bed that's 10 inches deep requires approximately 27 cubic feet of soil, which equals 1 cubic yard. Add 10% extra for settling as organic matter decomposes, bringing the total to 1.1 cubic yards or 30 cubic feet. Most bagged soil comes in 1.5-2 cubic foot bags, requiring 15-20 bags total. Bulk soil delivery proves more economical for multiple beds but requires wheelbarrow transport from driveway to garden location.
Can I build a raised bed directly on grass without removing it?
Cardboard over grass creates an effective method for bed placement without grass removal. The cardboard kills grass beneath while decomposing to improve soil structure within 6-8 months. Cut grass very short before placing cardboard and bed frame for best results. Overlap cardboard pieces by 6 inches and remove all tape and staples to ensure complete coverage. This method works for most locations except extremely wet areas where decomposing grass may create drainage issues.
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Written By
M
Mike Thompson
Mike's been designing residential landscapes in the Seattle area, with a particular focus on Pacific Northwest natives and sustainable practices. He's a Washington State Master Gardener and worked in construction before landscaping, which gives him a practical edge when it comes to building raised beds and hardscaping projects. He runs a small side business propagating and selling unusual perennials at farmers markets on weekends. His property serves as a testing ground for low-maintenance, wildlife-friendly garden designs. Mike's philosophy: if it requires weekly maintenance, it's not sustainable.
