Pressure Treated Wood for Edging a Garden

About Garden Edging

• Garden edging creates neat borders to separate hardscapes like sidewalks and driveways from lawn areas, to provide easier mowing and weeding and to create curves and shapes that add to the overall landscape design. Many different types of edging materials are available including metal, plastic, brick, concrete, stone and lumber. All these materials have advantages and disadvantages in regard to cost, durability and resistance to rotting or insect damage.

What Is Pressure-Treated Wood?

• Wood material used outdoors is treated with chemical preservatives to prevent damage from insects, moisture and fungus growth. Chromium, copper and arsenic are the chemicals used in this process. These chemicals are hazardous to human health and should be used with caution. Alternative preservatives are available that are safer to use, according to the Massachusetts Department of Environmental Protection.

Problems of Pressure-Treated Wood

• Normal exposure to the elements can cause the chemicals to leach from pressure-treated wood, contaminating soil and creating a danger of ingestion from garden edibles. Arsenic has been associated with higher rates of lung and skin cancers and should not be used around children, whose young tissues are particularly susceptible to cancer-producing agents. Pressure-treated wood should be sealed to prevent leaching of chemicals. Plastic lining between treated lumber and soil using for growing garden plants will help to prevent contact between plant roots and treated lumber, according to the University of Missouri horticulturalist Christopher J. Starbuck.

Alternatives to Pressure-Treated Wood

• Gardeners and homeowners concerned about hazardous chemicals used to preserve wood can choose one of the other types of materials used for landscape edging, such as brick or metal. Composite lumber, made from wood fibers and recycled plastic, offers an effective alternative to pretreated wood, according to the Environmental Protection Agency. Though more expensive than wood, it offers the same natural appearance without the chemical preservatives. It can be subject to mold and mildew, however. Redwood lumber is another option; it is more expensive than regular wood but offers the same natural wood appearance, though it can sustain moisture problems. Tropical hardwoods from sustainably managed forests is yet another option, but these woods may be hard to obtain and are expensive. Vinyl and plastic materials molded to look like wood may not be as attractive and can fade in color over time.