The garden timbers available at most home and garden centers today are made of core wood from trees that have been processed into plywood and are rarely hazardous to use in your garden. If heavy metals were used to treat these wood products before turning them into mulch, avoid using the mulch in an orchard. As a safety measure in the face of the many variables that influence a particular site, it is advisable to avoid wood treated with CCA for landscape use. These residential products generally consist of garden timbers, porch and patio decks, picnic tables, children's play structures, fences, and walkway materials purchased from local timber outlets.
While you can create the walls of a raised bed with cinder blocks, bricks, and even sandbags, one of the most popular and attractive methods is to use treated logs to support them in the ground. It is often used to outline a border, to trim various types of beds containing flowers or shrubs, in the construction of compost containers, and for raised beds for flower and vegetable gardens. If you have already done landscaping work with pressure treated wood, it shouldn't be a problem for landscaping plants and flowers. The best for making raised garden beds is naturally rot resistant wood such as black lobster, red mulberry, osage orange, Pacific yew, eastern or western red cedar, black cherry, honey lobster, white oak, Douglas fir, redwood, etc.
If you are worried about using wood treated on a raised bed of vegetables, regularly perform a heavy metal soil test in addition to a standard soil test. One of the most effective ways to grow a large amount of food in a small space is to use raised bed gardening or square foot gardening. Cover your bed with untreated wooden planks to make a flat surface to sit on and avoid contact with wood, especially if you have CCA treated wood in your garden. In May, Fine Gardening committed to planning and planting a garden for Karen, an emergency department nurse.
Currently, wood purchased at residential landscape wood outlets is treated with micronized copper azole (CA) or alkaline copper quaternary ammonium (ACQ). While these three chemicals are micronutrients and are found in any good garden soil, excessive amounts caused by wood leaching are thought to be dangerous, especially in root crops such as carrots and potatoes. Liming at a pH of 6.5 according to a home garden soil test will reduce some of the metal uptake by plants.