Choosing the right lumber for your landscape is dictated by how you plan to use it. Lumber is rarely used for anything below ground level unless it has been pressure-treated, a process of soaking the wood in a chemical preservative that renders the wood resistant to deterioration. Slices of naturally rot-resistant wood logs make economical stepping-stones, although over time even these will deteriorate. Redwood, cypress and cedar add a rustic elegance to your landscape, while composite wood is splinter-free, adds clean lines and is essentially maintenance-free.
Redwood has a natural, rustic look and is naturally rot-resistant. Common-grade redwood lumber is used in landscaping for framing outside structures, decks and railings. Construction-grade or heartwood -- the center of the tree -- is used for posts and near-ground structures. Redwood has a very distinctive red hue that weathers to a brown-gray. The natural color can be preserved by applying a sealant approximately every two years.
Naturally rot-resistant, cedar is used for its strength, is lightweight and has good weathering properties. Common-grade cedar should be used above ground, while heartwood cedar can be used for ledges, posts and near-ground structures. Light red cedar will weather to a tan to light gray. Sealants will change the color, turning it a dark gray. Stains can be applied to match your landscape color scheme.
Cypress is naturally rot-resistant and logged primarily in the Southeast, where cypress is a popular alternative to cedar. As you move west however, it can get pricier because of shipping costs. As with redwood and cedar, common-grade cypress should be used above ground, and heartwood can be used near ground and in dry areas where rot will not be a problem. Cypress has a slightly lighter color than cedar with an obvious grain pattern. If left untreated, cypress will weather to a pale gray.
Pressure-treated wood can be used above and in ground and is heavier and stronger than most other landscape lumber because it is saturated with chemical preservatives. Pressure-treated wood and railroad ties should never be used in food gardens because the chemical in the wood can leach into surrounding soil and into local water systems. Most pressure-treated lumber is easily recognized by its greenish color that eventually weathers to a dull gray.
Wood composite products that look like wood, act like wood, cut like wood and last longer than wood are another option. Manufactured by using wood fiber and resins or plastic, composite wood is highly resistant to decay, rot and insects, so ultimately doesn't need sealants or preservatives. Composite wood needs virtually no maintenance except occasional cleaning.
- University of Minnesota Sustainable Urban Landscape Information Series; Selecting Wood for Outdoor Structures; Jeff Fahrenholz
- Landscape Design Advice: Types of Wood for Your Decking or Landscape Structures
- Design Ideas for Home Landscaping; Catriona Tudor Erler
- Polka Dot Images/Polka Dot/Getty Images