Safe Wood for Vegetable Gardens

Organic certification standards prohibit the use of pressure-treated wood in soil where plants will be grown. Poisonous chemicals that are used to pressure treat lumber for insect and rot protection can leach into garden soil, where they can be taken up by plants. To build safe raised beds, fencing and other wooden garden structures, use wood that is free of toxins.

Untreated Wood

Untreated lumber is the safest to use in the vegetable garden.  Redwood, red cedar and bald cypress trees grow in the US.

and provide lumber that is naturally insect and rot resistant.  The highest grade of any of these varieties is the unblemished heartwood from the center of the tree.

You can use other species of untreated lumber, but they are not insect or rot resistant. 

Borate-treated Wood

Wood treated with disodium octaborate tetrahydrate (DOT borates) is decay and insect resistant and is safe to use around food plants.  Slight leaching of the borates may occur, which can affect plants' growth.

DOT is not poisonous to humans or pets, but it will kill fish and aquatic plants if it leaches into water.  Do not use DOT lumber near ponds.

Toxic Pressure-treated Wood

The Environmental Protection Agency recommends that pressure-treated wood processed with toxic chemicals such as chromate copper arsenate (CCA), ammoniacal copper arsenate (ACA), and ammoniacal copper zinc arsenate (ACZA) should not be used near animals or food crops. 

About the Author

Fern Fischer's print and online work has appeared in publications such as Midwest Gardening, Dolls, Workbasket, Quilts for Today and Cooking Fresh. With a broader focus on organic gardening, health, rural lifestyle, home and family articles, she specializes in topics involving antique and modern quilting, sewing and needlework techniques.