How To Tell If Wood Pallets Are Safe To Use In The Garden

You don’t have to be Christopher Lowell to know how easy it is to create wonderful things out of what others might consider trash.

Take, for example, the wooden pallet, which is often discarded after use. You can use them as building materials for a wide range of garden projects, such as raised garden beds, compost bins, or vertical planting racks. 


They can also be used to make things, including chairs, patio pallet furniture, and toy boxes for planters.

However, you should know a few things before grabbing a discarded pallet.

Let’s take a peek at what you should look out for when shopping for used pallets for the garden space. So read on to learn more about the types of pallets and pallet safety.

How To Tell If Wood Pallets Are Safe To Use In The Garden

There are two major concerns when using wooden pallets: bark content and treatment method.

And if the pallet doesn’t meet ISPM 15 standards, it is probably unsafe for use around your plants. So what pallets are safe to use?

The IPPC and ISPM 15

In 1951, an international treaty was created by the United Nations Food and Agricultural Organization.

Known as the International Plant Protection Convention (IPPC), the treaty governs the protection of native plants and plant products from pests and invasive plant species.

Moreover, wood pallets with IPPC markings are often used for international shipping. In contrast, pallets without any marking are called national pallets and are used for domestic transport.

There are several regional organizations that oversee the enforcement of the IPPC, although we won’t go into those.

What’s more important is that the IPPC released a requirement known as International Standards For Phytosanitary Measures No. 15 (ISPM 15).

ISPM 15 requires a special IPPC stamp on wooden pallets which displays how the pallet was treated to remove any pests, as well as other important information.

In 2009, the standard was updated to include a debarking rule.

Understanding the IPPC Stamp

The wooden pallet should have an IPPC stamp on two opposing sides.

If you don’t see this stamp, you shouldn’t use the pallet around your plants.

The IPPC label includes the IPPC logo, the certification symbol, the country of origin, and a two-letter identification code that shows how the natural wood was treated.

Some other information that might appear include a unique numerical code assigned to it, the inspector’s mark, and an indication if the pallet is bark free.

There are four main two-letter identification codes on the pallet stamps you’ll see:

  • DB – Debarked
  • HT – Heat treated wood pallet, heat treating or heat treatment
  • KD – Kiln-dried
  • MB – Methyl bromide

Kiln-dried pallets have been treated in a kiln to remove water content, making them more resilient against rot or fungal growth, and may be considered heat treated.

MB is the pallet marking you will need to watch out for, as this denotes the pallet isn’t safe for use around your plants. This is because MB pallets are treated with Methyl Bromide, a dangerous chemical.

What is Debarking?

In 2009, the ISPM 15 was updated to include a debarking requirement.

The term “debarked” refers to wood that has most of the bark removed but may contain small traces of bark.

“Bark free” is a more strict standard in which no bark traces are permitted, which will be written out on the pallet if there is no bark content.

Debarking the wood before treatment helps prevent the raw wood from being reinfested before or after manufacturing.

While not essential for a pallet to be safe in the garden space, using debarked or bark-free wood will help reduce the risk of the pallet becoming infested.

The Dangers of Methyl Bromide

Methyl bromide is the common name for bromomethane, a natural substance produced both in nature and synthetically.

It’s still used in a wide range of industrial applications, although most countries have largely phased out its use as a pesticide for killing invasive species in the past two decades.

This toxic chemical is still used for some fumigation applications, such as with wooden pallets. However, Methyl bromide treatment use in sterilizing soil has been halted due to the gas’s negative effect on the ozone layer.

While ISPM 15 allows for the use of methyl bromide in treating wooden pallets, this odorless gas can still contaminate the air around it as it’s slowly released from the wood and is considered toxic.

That said, you can safely use MB pallets that underwent chemical treatments and contained methyl bromide in many crafts, but you should avoid putting them in the garden or any of your indoor projects.

Moreover, human exposure to high concentrations of this toxic chemical can cause be hazardous to human health. It can cause respiratory and central nervous system failures, harming the eyes, skin, and lungs.

Wooden Pallets Exempted from ISPM 15

Another important thing we need to address is that many types of wooden pallets are exempt from ISPM 15 and may not have an IPPC stamp.

  • Composite wooden pallet blocks are made from recovered wood chips which are glued and formed using high heat and pressure.
  • Corrugated pallets are glued wood pulp and are heat treated by default.
  • Plywood and processed wood pallets, such as particle boards, use processed wood materials that are glued and compressed using either high heat or pressure.
  • Presswood pallets are made from recovered sawdust or wood chips that are glued and formed using high temperature and pressure.

These four types of wooden pallets are far less likely to be infested and rarely, if ever, are treated with methyl bromide.

As they contain glue (which may or may not be from an organic source), you will need to use your discretion when picking up these pallets.

Generally, it’s a great practice always to read the pallet codes to ensure you’re using safe pallets for your garden and plants.

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