Pressure-Treated Lumber for a Raised Garden

Advantages

• Pressure-treated lumber is often considered for raised garden beds because of its durability. Untreated lumber will weather and fall apart quickly compared to pressure-treated lumber and must be replaced much more often. This can be expensive and time consuming. It can also be a difficult job, depending on the construction of the beds. Pressure-treated lumber will last for many years without weathering or wearing down.

Disadvantages

• The major concern with the use of pressure-treated lumber for a raised bed garden is with the chemicals used to treat the wood. Since the lumber is in close proximity to vegetables being grown for home consumption, gardeners worry that the chemicals could leach into the soil and eventually wind up in the vegetables they consume. Although the risk of such contamination is low, any risk is not acceptable for many home growers.

Safety

• Arsenic was once one of the chemicals used in pressure-treated lumber, but since 2003, a different, safer chemical composition that does not include arsenic has been used. Numerous studies have been conducted on the rate these chemicals leach into the soil and are taken up by common garden plants. Generally, only small amounts were taken into the roots of the plants and were not transferred into the edible portions. A few exceptions were found, however, including leafy vegetables, like spinach, and root vegetables like potatoes, turnips and carrots. Even so, the levels in these vegetables were not found to be higher than the levels in the same type of vegetables purchased at the grocery store.

Alternatives

• Although pressure-treated lumber has been found safe for most home garden raised beds, a number of alternatives that do not pose the same risks are also available. Long-lasting natural lumber, such as redwood, is a suitable choice for raised beds. Composite or plastic lumber can also be used to construct beds. Stone and bricks are other common materials used in raised garden beds.