Are tire gardens toxic?

In a newsletter a couple months ago I shared some thoughts on tire gardens along with this video:

In response, one of my readers wrote:

“Hello David,
Tires do leach toxic, carcinogenic chemicals in to the soul and plants grown in them. No time to research this? Then do not show pictures of plants grown in tires. That is irresponsible and bad karma as you pass on injury to others. Look in to it. Fact. Tire gardening and straw bale gardening are bad if you do not want toxin-suffused vegetables.”

And Sheila writes:

“One year my father and I planted potatoes in tires. Just put on another Tire and add dirt we had lots of potatoes with seven high.PVC pipe with holes in it to water the plants.  Problem was that they tasted like tires. Since then I am not a fan of tires for living or gardening.”

Vegetables tasting like tires? And bad karma! Oh me oh my, I just want to give up.

Actually, I don’t care about tire gardens, though I do like the idea of recycling a waste product into a gardening bed.

But growing vegetables in tires isn’t a method I have any personal stake in.

Unlike Joel Karsten, the Straw Bale Gardening Shill, I’m happy to drop this method if the evidence is against it.

So – are tire gardens toxic? Let’s do a little digging.

Are Tire Gardens Toxic: The Case For Tires

Tires are, of course, cheap and widely available even in the third world. ECHO uses them in their urban garden demonstration area. You can set up tire gardens on driveways, roof tops, rocky lots and in tight spaces.

They’re convenient, too. But are they toxic?

When Patrice at Rural Revolution blogged about their tractor tire gardens, she got a similar response to that which I got but even harsher.

Someone wrote:

“You could have created a floral landscape, a Dutch Masterpiece, an English Rose Garden, a French Formal Garden, and you chose Fords-Ville, Michelin Man, and polluted Mother Earth. Scrap timber is everywhere, so are bricks, tiles, even rockery stones, but tyres no. Are you sure the food grown will be free of carbon rubber tyre oil moisture? A carcinogen?”

You can read Patrice’s response and entire defense of tire gardening here, but most of it boils down to what she wrote here:

“Tires have a lot of nasty things bonded into them, things that arguably ARE carcinogenic. But it’s the term BONDED that must be considered. Intact tires are distressingly inert (that’s why they’re everywhere rather than quietly decomposing into Mother Earth).”

She then quotes extensively from research done by Mr. Farber of www.tirecrafting.com (which now redirects to an Etsy site so the original essay appears to be missing):

“Used tires already exist and in their solid state they are as safe or safer than any other construction material. The process and the result of this global discard nightmare being recycled by industry, whether grinding them up for road base, burning them as fuel, or recouping the oil, releases more hydrocarbons while costing the global economy billions of dollars for tire cleanup and commercial recycling. Modifying tires to create green space and home gardening available to everyone would not only absorbs hydrocarbons, it could well be the key to salvation for practically every family on the planet that is otherwise excluded from adequate sustenance. Personal tire recycling potential benefits far outweigh all perceived hazards.”

Still, I am not convinced. After all, if vegetables are tasting like tires, well, that doesn’t inspire confidence. Yet I do love what Patrice has done at Rural Revolution. In her case, it made sense.

Are Tire Gardens Toxic: The Case Against Tires

According to Brighton Permaculture Trust:

“Due to commercial secrecy, it’s difficult to find out the exact ingredients of a tyre, and there are lots of different types. The list below is from a ‘typical tyre’:

• Natural rubber
• Synthetic rubber compounds, including Butadiene – known carcinogen
• Solvents: Benzene – known carcinogen, Styrene – anticipated to be carcinogenic, Toluene – has negative health effects, Xylene – irritant, & Petroleum naphtha
• Polycyclic aromatic hydrocarbons: Phenols – some are endocrine-disruptive, Benzo(a)pyrene – linked to cancer
• Heavy metals: zinc, chromium, nickel, lead, copper & cadmium
• Carbon black – possibly carcinogenic
• Vulcanising agents: Sulphur & Zinc oxide
• Polychlorinated biphenyls – known carcinogen
• Other synthetic chemicals”

Again, though, these terrible things might have off-gassed during the tire’s usable life or been stabilized and made inert during manufacturing.

Yet as Mischa argues in that article:

“When it comes to growing food in tyres, why take the risk?

Whilst the quantity of toxic chemicals maybe small, we don’t know the exact amount used in tyres because of commercial secrecy.

People generally grow food organically for themselves to avoid exposure to synthetic chemicals. It seems ironic that a ‘Permaculture way’ of reusing tyres could be unintentionally reintroducing potentially harmful chemicals back into the equation.”

And over at Science Daily, it gets scarier:

“Draper’s method has been to make up clean samples of water like those inhabited by several kinds of aquatic organisms — algae, duckweed, daphnia (water fleas), fathead minnows, and snails — and under controlled laboratory conditions, put finely ground tire particles into the samples. By letting the particles remain in the water for 10 days and then filtering them out, she created a “leachate” that included substances in the tire rubber. All the organisms exposed to the leachate died, and the algae died fairly quickly.”

This is not complete tires, of course, but tires will break down slowly over time in the garden – and if it kills ground life, well, that’s obviously a bad thing.

The science isn’t settled, but it is disturbing.

Conclusion

After multiple hours of research, I am now leaning against tire gardening.

If you’re in an urban setting, have terrible soil or no soil and no options, etc., there might be a place for tire gardens. I built mine for fun in a few minutes and have enjoyed them but I now have no desire to expand and add more. Yet digging beds is free – so why use tires at all?

Especially if it’s going to ruin the karma I even don’t believe in.

If you want simple, tried-and-true and even off-grid methods for growing lots of food without much money in tough times, check out my book Grow or Die: The Good Guide to Survival Gardening.

As Sally writes in her review:

“great info without a lot of fluff. author has a good sense of humor – i laughed out loud a few times. i would recommend for anyone getting started with a home garden who wants to stick to the basics instead of gimmicks“

Check it out – I think you’ll enjoy it.

*Image at top by Tony Buser. CC License.