What Wood is Safe to Use in My Garden?
By Dr. Leigh Whittinghill, Assistant Professor of Urban Agriculture
Pallets are readily available and versatile. They can be used to make horizontal or vertical gardens or repurposed as many other things. When selecting a pallet for use, there are a few things you should consider:
First, look for the International Plant Protection Convention (IPPC) logo. The IPPC developed the International Standards for Phytosanitary Measures No. 15 (ISPM 15). This is a standard that requires all solid wood packaging material to be treated and marked to prevent the spread of disease and insect pests. If you can’t find this logo, it is best to avoid using the pallet because you will not have clear information about how it has been treated.
- Examine the treatment code. There are several treatment codes used by IPPC:
All pallet wood has had the bark removed using a cutting tool and may carry the designation DB, which stands for debarked.
The heat treatment (HT) symbol indicates wood that has been heated to achieve a minimum temperature of 56circC throughout the profile of the wood for a minimum of 30 continuous minutes. If this is the only treatment code, this wood is otherwise untreated and safe to use.
The methyl bromide treatment (MB) symbol indicates the wood was fumigated with methyl bromide to achieve a minimum concentration of methyl bromide throughout the wood This wood is considered unsafe for use in the garden or as compost bins.
Both heat treatment and treatment with methyl bromide are used to kill potential invasive insects and pathogens
Country codes. Pallets will also have a two letter country code (e.g., CA for Canada, US for United States, MX for Mexico). This may give you an indication of how the pallet was treated because regulations and practices differ among countries. Some people avoid imported pallets because of this, although all pallets marked with IPPC should meet their standards.
Example of Pallet Stamp
- The numbers after the country code indicate the supplier of that pallet.
Examine the pallet. If there are any spills or stains on the pallet, you may not want to use it. Colored pallets should also be avoided as they are often used to ship toxic chemicals.
You may find other markings on a pallet. These may include markings of an inspection agency, a specific country or region specific, a manufacture date, or may indicate an uncommon type of wood. EPAL, for example, means that the pallet meets the modern European standards and are safe for use. If you find one you are not sure about, try to look it up and determine what it means before you use the pallet.
If you are unsure about reusing a pallet, new pallets can be purchased.