Cedar is a top material choice for planter boxes due to its durability and attractive appearance. Home gardeners often seek materials that perform well in wet conditions while remaining safe for growing food. This article examines the specific attributes of cedar to determine its suitability as a long-term solution for various planter box needs.
Inherent Properties That Make Cedar Ideal
Cedar is a lightweight softwood prized for its natural resilience against the elements and biological threats. It contains naturally occurring chemical compounds, primarily polyoxyphenols, which act as a built-in defense system. These compounds are responsible for cedar’s characteristic aroma and its ability to repel insects and resist fungal decay.
This natural resistance means cedar does not require chemical treatments to achieve longevity in outdoor applications, unlike many other softwoods. Cedar has a fine, uniform grain and is relatively light, making it easy to cut, handle, and assemble into various planter box designs. The wood’s cellular structure also offers insulating properties, helping to moderate soil temperature and moisture fluctuations, which benefits plant roots.
Safety and Suitability for Edible Plants
For anyone planning to grow edible plants, the chemical safety of the planter material is a primary concern. Untreated cedar is consistently regarded as a non-toxic and safe option. The natural oils that give cedar its rot resistance do not leach harmful substances into the soil that would contaminate food crops.
This provides a significant advantage over pressure-treated lumber, which historically used chemicals like chromated copper arsenate (CCA). While modern pressure-treated woods use copper-based compounds, the potential for chemical leaching still leads many gardeners to prefer cedar for food cultivation. Choosing untreated cedar eliminates uncertainty regarding the transfer of preserving chemicals into the planting medium.
Expected Longevity and Weathering Process
Cedar planter boxes typically last between 10 to 15 years, depending on the climate, construction quality, and cedar variety used. The longest-lasting wood is the heartwood of rot-resistant varieties like Western Red Cedar. Constant exposure to moist soil is the primary factor that eventually leads to structural deterioration, usually starting where the wood contacts the wet earth.
The wood’s appearance changes significantly over time through weathering. When left untreated, cedar’s initial rich, reddish-brown color will gradually fade. Within a few years, the surface develops a silvery-gray patina as the sun’s ultraviolet rays break down the surface wood cells. Applying a non-toxic sealant or oil is an optional step that can help preserve the original color, but it is not necessary to maintain the wood’s structural integrity.
Comparing Cedar to Other Common Planter Materials
Cedar is generally considered the premium wood option, reflected in its higher cost compared to standard lumber.
A primary alternative is common framing lumber, such as pine or fir, which is more affordable initially. However, these non-resistant woods rot quickly, often lasting only a few years when exposed to damp soil, making them a poor long-term value.
Pressure-treated lumber is a cheaper, highly durable alternative, but it carries the concern of chemical transfer, even with modern treatments. Redwood offers similar rot resistance and longevity to cedar but is typically more expensive and has limited regional availability.
For gardeners seeking maximum durability, non-wood options like corrugated steel or composite materials may be considered. While these materials offer an almost indefinite lifespan and eliminate rot concerns, they often come with a higher initial cost than cedar and lack the natural aesthetic of wood.