Redwood or Black Locust – Definitely the best option for raised garden boxes in terms of longevity because they are naturally rot-resistant and have been known to last up to 20 years. Douglas Fir – Douglas Fir can last 5-7 years, and is the cheapest of the types of wood used for raised garden boxes.Click to see full answer. Considering this, is Douglas fir good for ground contact?It is a native species that only grows in U.S. Department of Agriculture plant hardiness zones 5 and 6, and although not a true fir, it is the most rot-resistant of the firs. Douglas fir boards hold up well for three to six years when in direct contact with the ground.Secondly, how Long Will Douglas fir last in the ground? 10-15 years Furthermore, what is the best wood to use for a raised garden bed? cedar Is Treated Wood OK for raised beds?Yes, the “new” pressure treated wood is safe for use for raised garden frames with a few precautions! Up until 2003, the most common preservative used for pressure treated wood was chromated copper arsenate (CCA), a compound using arsenic as its primary rot protectant.