URBAN PLANTER BOXES

If you're building urban planter boxes, the question of pressure-treated wood safety is crucial. Modern pressure-treated lumber, used since 2004, primarily employs ACQ (Alkaline Copper Quaternary) or copper azole, which are considered lower risk than the old CCA (Chromated Copper Arsenate) treatment. The copper acts as a fungicide, with the other components helping it fix to the wood. For above-ground planter boxes, the risk of these copper compounds leaching into soil in significant amounts is generally low, especially if the wood is lined with a heavy-duty plastic barrier. However, many organic gardeners prefer untreated, naturally rot-resistant woods like cedar or redwood, or use composite lumber to eliminate any concern. If using older, reclaimed wood, avoid any lumber marked "CCA" for vegetable contact. For ultimate peace of mind, creating a physical barrier between any treated wood and your soil is the most recommended practice for edible gardens.