Toxic Materials You Shouldn’t Use for Building Raised Beds For Your Garden (With Better Alternatives)

Raised beds are a great way to grow gardens, particularly in climates with plenty of rain. (In dry climates, where water is at a premium, it can actually be better to use sunken beds, which will capture water when it does come.)

By design, raised beds help to ensure that the soil will drain adequately so that those plants won’t get waterlogged, leading to root rot. Even better, high-quality soil can just be added to the bed, so there is no need to have naturally great soil in the garden space.

There are lots of other reasons, too. They require less bending and no digging. They deter some garden pests, like groundhogs and slugs. They also have fewer weed issues. They are nice and neat, easy to maintain, and can be easily moved if necessary.

However, many people make the mistake of using questionable materials to create their raised beds, so let’s look at some of these materials and easy alternatives that are safer.

Pressure-Treated Lumber

Source: The Honest Carpenter/Youtube

Treated lumber has been impregnated with chemicals that help it resists fungus and insects, preventing it from rotting. This can be useful (and, in fact, is required) when building certain parts of a house, but these chemicals can leach into the soil and aren’t something we want our food to absorb. Older treated lumber was infused with copper arsenate, which can potentially expose a garden to arsenic. Nowadays, treated wood has gotten rid of the arsenic, using alkaline copper quaternary, but the overabundance of copper can cause issues, too.

• Safer option: Though untreated lumber might not last as long, it won’t come with health concerns. There are naturally rot-resistant woods like cedar, redwood (sustainably harvested, of course), and cypress that can extend the life of the bed.

Railroad Cross Ties

Old railroad cross ties have been very popular for building garden beds for decades, but they aren’t good for growing edible stuff. They were treated with creosote, another strong pesticide that repels pests and fungus, but again, this will leach into the soil near it. This can be bad for the food, as well as the plants, small animals, and insects.

• Safer Option: Raw wood, like long logs or stumps, can work very well and provide a more natural, rustic look. White oak, black locust, black cherry, and cypress are all rot-resistant as is and a thick log will last a long time.

Cinder Blocks

Cinder blocks are yet another very common material used to make raised beds, but they have unsavory elements that can cause leaching problems with the soil and make food unsafe to eat. They contain fly ash that can have toxic metals like lead, arsenic, and mercury. Plus, they come with a huge carbon footprint.

• Safer Option: Masonry bricks are a much cleaner option. They are made from clay, and they are often easy to find used. Repurposing old bricks will mean a much smaller footprint and no chemical problems.

Concrete “Stones”

Many of the same problems that come with cinder blocks are the same for fabricated concrete stones. Concrete is created with a very energy-intensive process, and It contains materials that might leach into the soil. Why go through all the trouble of growing an organic garden in a questionable material?

• Safer Option: Natural stones are a much better option than fabricated stones. They can be a little tougher to stack, but they can also be a much more rewarding and interesting project. It’s more than just a pile of rocks!

MB-Stamped Pallets

Source: Project Diaries/Youtube

Repurposing pallet wood is great for those who can acquire them for free or cheap. However, pallets that are stamped with the initials MB have been treated with methyl bromide, another harsh chemical preservative that we don’t want leaching into our soil and, thus, food.

• Safer Option: HT-stamped pallets haven’t been treated with chemicals to preserve them. Instead, they are heat-treated to kill anything that might cause problems. They are much safer from upcycling.

Galvanized Corrugated Tin

This is another one of those materials that can come from a good place: repurposing old roofing tin to make garden beds seems an awesome way to reuse something constructively. Unfortunately, galvanized metal has been treated with zinc. When exposed to certain elements or materials like salt, this can leach into the soil and cause issues.

• Safer Option: Terracotta materials, like bricks, can be an interesting choice for making raised garden beds. Or, terracotta pots can be used to grow container gardens. This might be the perfect choice for growing food on patios or rooftops.

Old Tires

Older tires are easy to find for cheap or free, and people love to make little raised beds out of them. Regrettably, they are laced with chemicals like lead and cadmium that can foul the soil. It’s just not worth it, particularly when growing food.

• Safer Option: It’s totally possible and acceptable to make raised beds with no frame at all. Instead, just pile up soil and organic materials in whatever shape seems desirable. Mulch it well, and plant away.

Undoubtedly, different people will have different takes on these materials, some claiming they are absolutely safe to use. However, doesn’t it make good sense to just use what we know is safe?

Related Content:

• How to Make Instant Garden Beds the Permaculture Way
• How to Use Snow — Yes, Snow! — to Warm Up Garden Beds
• How and When to Use a Double-Dig Garden Bed
• How to Create a Sunken Garden Bed When Raised Beds Don’t Make Sense for Your Environment
• The Art of Making a Hugelkultur Garden Bed for Years of Fertility

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