If you're planning to build raised garden beds, you might be wondering about the safety of using treated wood. Rest assured decades of research and the latest findings confirm that modern treated wood products like Preserve® CA (Copper Azole) are safe for growing vegetables and herbs.
A 2024 multiyear study conducted by Dr. Presley and Oregon State Universityinvestigated copper migration in raised beds made from CA-C treated wood. After four years of real-world testing, results showed no increase in copper levels in vegetables grown in treated beds compared to those in untreated beds. The study confirmed a small, localized increase in soil copper concentration—about 20 ppm within 0–1 inches of the bed edge—but this increase remained well within the natural background range for Oregon soils and posed no risk to plant or human health.
Earlier research published by Wood Preservation Canada aligns with OSU's conclusions. Even root vegetables like carrots, parsnips, and radishes show no measurable uptake of copper. In fact, in some instances, untreated beds had vegetables with slightly higher copper content—likely due to natural soil variability. For added peace of mind, some gardeners choose to line beds with heavy-duty plastic sheeting, though studies suggest this is not necessary for safety.
Importantly, the concerns people associate with older preservatives like Chromated Copper Arsenate (CCA) are outdated—CCA is no longer used in residential applications. Today’s non-arsenical copper-based preservatives, such as CA, deliver durability and peace of mind.
Benefits of Using Preserve® Treated Wood:
- Durability: Resists rot, decay, and insect damage to help your garden beds last for years.
- Proven Safety: Backed by university-led research and four growing seasons of data.
- Cost-Effective: More affordable than naturally rot-resistant woods like cedar or redwood.
- Sustainability: Extends the life of wood, reducing material waste and frequent replacements.
Ready to Build Your Garden Bed?
Visit our DIY guide pages for detailed plans and inspiration:
Find Preserve® treated wood at 84 Lumber and other independent lumber dealers across North America. Check our “Where to Buy” page for a store near you. For more info on safe practices and raised bed construction, visit TreatedWood.com.