Until the safety of treated wood is proven conclusively, we recommend you use a naturally rot-resistant wood like red cedar, black locust or redwood. Under most circumstances, these woods will last 10 â€“ 20 years when used for raised beds.
Cedar and redwood are naturally water-resistant but can be expensive and hard to find. Hemlock, fir and pine are suitable materials for raised beds but aren't very long-lasting. Pressure treated lumber is an option.. Creosote-treated wood is not a good option for vegetable raised beds.
I am planning my first vegetable garden this year.. been afraid to use pressure treated lumber for my raised beds, based on what I've read.