What is the best material to use for raised beds?
Written by
Tina Carter
Reviewed by
Prof. Martin Thorne, Ph.D.Selecting the optimal materials for raised beds entails a consideration of three factors: safety for edible plants, durability, and reasonable cost. Untreated wood, such as naturally rot-resistant lumber from cedar, is an excellent choice, but one could also use pressure-treated lumber, which substitutes relatively safer copper for the former toxic arsenic. Galvanized steel trays support strength when treated correctly against rust. Each material corresponds to different gardening goals and environments.
Wood Options
- Cedar: Natural rot resistance lasts 10-20 years
- Pine: Budget friendly but needs yearly treatment
- Pressure treated: Modern copper based treatments are safer
- Avoid railroad ties and recycled pallets for edibles
Metal Choices
- Galvanized steel: Zinc coated for rust prevention
- Corten steel: Forms protective rust patina over time
- Aluminum: Lightweight and naturally corrosion resistant
- Always verify food grade certifications for safety
Stone & Concrete
- Natural stone: Minimal pH impact but expensive
- Concrete blocks: Affordable but raises soil alkalinity
- Require professional installation for stability
- Use sulfur amendments to counter pH changes
Your local climate influences the activity of materials. In areas with high humidity, I use rust-resistant metals, such as galvanized steel, instead of wood. In colder climates, stone serves as an excellent thermal mass to shield the roots. Areas with high heat require highly reflective aluminum to keep the soil from overheating. Always use materials that are compatible with your local climate patterns.
Safety certifications are the most important consideration for edible gardens. You will want to verify that your materials have a seal from OMRI for organic compliance or a NSF/ANSI 61 for food contact safety. After finding lead in some inexpensive bricks, I test all materials before planting. Use a layer of plastic barriers under concrete beds to prevent changes in pH that affect your vegetables.
Never let the budget compromise safety. Cedar fencing pickets are durable and reasonably priced, and sanitized pallets can also be a good choice for temporary flower beds. My initial garden was from salvaged materials, costing less than $30. You can always start small with low-cost options before making any commitment to a permanent installation.
Read the full article: Best Raised Bed Materials for Your Garden
