Hey Mr. Green,
I belong to the Cool Cities group Cool Joliet. We have a controversy over raised beds in a community garden. Should we use cedar wood or composite lumber for the beds? Composite timbers are a blend of wood fiber and UV-protected polypropylene, 100% recycled material, and the connecting joints made of durable ABS plastic resin. Will plastic leach toxic material into the soil, or is the composite better because it is all recycled and will last longer? --Lorna, Joliet, Illinois
While raised beds are a great idea, there are far better uses for cedar, such as furniture, armoires, and chests (cedar actually deters moths). Although cedar is rot resistant, if put in contact with the ground it will eventually decay and need replacement. (Of course I’m for easing up on the cedars in general, except in cases where they are invasive species. The famous cedars of Lebanon were among the first victims of deforestation, when the macho ur-logger Gilgamesh went furiously whacking them down more than 4500 years ago, as revealed in the Epic of Gilgamesh.)
Composite lumber is a greener choice for raised beds. In addition to being made of recycled material, the composite’s polypropylene and the ABS in the brackets will not leach toxic substances into the soil because they are considered safe for many applications—polypropylene even for baby bottles. In fact, the USDA organic farming certification program allows composite lumber for beds or fencing, in contrast to some types of treated wood, which is taboo if it’s too near to the crops. Composite lumber is also slow to deteriorate, as I can testify from use of it in my own raised beds.
Finally, congratulations to you guys in Joliet on joining the Cool Cities program. Those in other towns who might want to emulate your efforts, see http://www.coolcities.us/ .