ID #1006

Is it safe to use treated lumber for raised beds?

In 2004, the most widely-used treated lumber at the time, CCA (Chromated Copper Arsenate) was phased out because it contained arsenic. An EPA- approved (and arsenic-free) treated lumber, ACQ (Alkaline Copper Quaternary), was introduced as a substitute. Like CCA, ACQ is a wood preservative that prevents decay from fungi and insects, but because it doesn’t use arsenic, it is safe for raised beds.

If you already have CCA-treated raised beds that were built before 2004 and you’d like to continue using them, consider lining your beds with heavy plastic to prevent the soil from contacting the treated wood. Or you can plant your vegetables, especially your root crops, at least 12 inches from the sides of the beds, (and consider planting inedible flowers closer to the CCA-treated sides).

Although you may want to modify and continue using your CCA-treated raised beds, you should not make raised beds from any lumber that has been treated with creosote or pentachlorophenol (such as old telephone poles or railroad ties), as these chemicals can leach out into the soil and injure the plants.

If you don’t want to use treated lumber at all for your raised beds, consider using alternate materials including naturally rot-resistant woods such as cedar and redwood, synthetic wood (recycled plastic), vinyl fencing, stone, concrete block, and brick.

Use caution if you choose to get rid of your older, CCA-treated lumber. Wear a dust mask and thoroughly wash your hands, clothes, and the work area after cutting or working with CCA-treated wood. Don’t burn the treated lumber, as the smoke and ash are highly toxic. Also, don’t chip the wood to use for mulch or bring it to a composting site.

For more information about using treated wood for raised beds, see Pressure Treated Lumber & Raised Beds.

Tags: ACQ, arsenic, beds, CCA, copper, gardening, lumber, raised, treated

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