Topic: Spuds'n'tyres

[feet of clay]

Has anyone grown spuds in tyres?  I was wondering if you get a decent yield and how many tyres high is advisable. My first earlies have cropped nicely in big pots but I can get the tyres free and felt I could earth them up even higher....

[kenkew]

Inside-out tyres would be about the right size, some on here don't advise it due to possible chemical problems. Don't know how much of that is based on fact, no doubt someone will step forward with a bit of science.

[Multiveg]

Bob Flowerdew was asked about this on Gardeners Question Time last week. He suggests a maincrop rather than an early. Out of the 2,000 that went to the summer garden party, 7 grow spuds in tyres. Bob said that there were 2 million listeners to GQT, so that means 70,000 people grow spuds in tyres, and that is an awful lot of tyres that are not going to landfill.

As for chemicals, on one forum, there was someone advocating NOT using plastics as the nasty chemicals in that leak out.

[john_miller]

    Not the site I wanted but useful anyway and repeats what I read elsewhere:
http://www.dot.state.mn.us/environment/research/comparative_risk_paper.html
    Scroll down to summary and conclusions if you don't want to read the whole thing. Tyres immersed in water as a substrate for roads will probably react similarly when exposed to the constant moisture that is inherently needed for vegetable growing.
   You will not find any research concerning the potential toxicity of tyres when associated with human food production as, in many technologically advanced countries, it is illegal to use products for a purpose for which they were not intended. Bob Flowerdew should know all this. However much we may all want to recycle there is no point in taking unneccessary risks.

[Ceri]

I'm doing the tyre thing with courgettes, with great success - taking on board John's advice when I first raised this - I 'lined' the tyres with visqueen dpm, laid them on dpm and cut a small whole for the roots to go from tyres to soil bed.

I understood from a whizz through John's article that the biggest problem is leaching zinc when tyres are underwater.  They're not underwater on my plot, and the dpm separates the tyre from the damp compost and soil so I'm comfortable with using them in this way at the moment.  Weeding and watering is so so easy

When courgettes first in, used tyres as coldframes with a big of glass on top.

[philcooper]

Bob and the HDRA both recommend tyres as a "container" soi they can be all that bad!!

[john_miller]

With all due respect to Bob Flowerdew and the HDRA, and while it is not my intent to contradict or change those who are already doing it, when I read research like this-
http://216.239.41.104/search?q=cache:Ki2r05qXFDUJ:www.ciwmb.ca.gov/Publications/Tires/43296029.doc+constituents+of+tires&hl=en
 I will continue avoid growing vegetables in tyres or in any other containers not approved for food production or storage. For those not wishing to read the whole thing sections 3.1 and 5.4 are summaries of the issues that trouble me.
  I entered horticulture in the mid-'70's. At this time growing in a flowing solution (Nutrient Film Technique) had just been perfected and, in an effort to boost production, my employer put me in charge of installing systems, and subsequently running them, over each of two seasons. It was impressed upon me that I, and my peers, had to be really careful when laying down the troughs that the solution ran in as they were made of plastic that was approved for food production. This plastic was made without any of the typical additives that are put in plastics to condition them. These additives can leach out in water and many are toxic.
  When I moved over here a couple of years later my employer here was also interested in growing tomatoes as an out of season crop. However, his greenhouses were set up for bedding plants so he was also interested in some sort of hydroponic production. Because the troughes were not available we decided to grow the plants in 2 gal nursery pots with me in charge again (I had in the meantime been to college and did a dissertation on plant nutrition). Just as the first crop was maturing I persuaded my employer to send some plant tissue for analysis so that I could better judge the nutrient regimen I had used. I cannot remember the results of the analysis beyond the finding that the plants had such high levels of cadmium, a toxic heavy metal, in them that the laboratory couldn't measure it. When I asked my horticultural adviser (a Ph.D in Plant Science from Cornell University, so he knows something about this in my opinion) where this could have come from he informed me that cadmium was used to re-inforce and strenghten the plastic pots. It had leached from the pots and being taken up by the plants. This brought home to me why my U.K. employer had used the troughes that he did.
  When I subsequently set up my own hydroponic system to grow lettuce, special troughes were, by then, available over here (developed by a Dr. Schippers, who emigrated here to teach at Cornell). All my header pipes and return pipes were adapted, commercially available 'Schedule 40' (cleared for use with potable water) pipes. This was used for the same reason.
  The question of growing potatoes in tyres was raised on the BBC boards a while ago. Being new to me I did some research at that time. The web page I have posted above indicates some of the potential problems with leachate problems, including cadmium which, as I have indicated, I have had personal experience of the possible problems. Additionally, my earlier research told me that chromium (another heavy metal), formaldehyde and dioxin are all used in tyre production. Traces of these compounds may be present in tyres.
  While I really don't wish to take issue with the HDRA about anything, during the discussion on the BBC about tyres, someone else contacted them and was told that they had never heard of cadmium being used in pots. Anticipating national differences I did some checking and found the DEFRA site that stated that cadmium had only been phased out of plastic pot production the year before (and included the statement that there was a commitment to phase out lead by 2005)
  The use of a plastic membrane, such as Visqueen DPM, unless approved for use with potable water, will not overcome these problems either, as the plastic may itself leach contaminants that plants can metabolise. One article I read in Smithsonian magazine years ago mentioned that some cancer researches had unexpectedly induced cancer growth by using previously approved plastic caps on some test tubes (the problem went away when they started using glass caps).
  Hopefully I haven't bored everyone to tears with this. Those who are interested may find this information useful.

[john_miller]

Yes. The questions become: how much is enough (being higher up the food chain, we will concentrate toxins)? should we, as individuals, try to avoid unneccessary exposure (given that so much is unavoidable)? Recent legislation is reflecting a desire by people to gain control over their environment (a bumper sticker over here reads: Where the people lead, the leaders will follow). I believe that when armed with knowledge people will make decisions best for themselves without waiting for their political leaders to delineate such (I wonder why I live in the land that champions individual freedom so much?).
I'm just posting this for informations sake. Everyone individually has to make their own decisions (as Bob Flowerdew obviously has done). My stance is probably obvious. If it isn't, I would add that I excluded all plastics from my kitchen after reading the Smithsonian article! Please, anyone heard of wooden computers?

[kenkew]

Should I stop using cling flim to wrap-up my plotty butties?

[feet of clay]

Very interesting.  I won't have plastic window frames because of the emissions ( also cos I don't like the look and I live in an old house).  Worrying too cos I grew my spuds in plastic pots and my toms are in them too! (And my aubergines, peppers, chillies & courgettes.)

[gavin]

Thanks for that, John.  Good to have the reference - AND the interpretation!  I'd have been lost without it :) :) :)

One little phrase says it all?  Somewhere near the bottom - "Lots of research into how the environment affects tyres, but very little the other way round."  (Not that I'm complaining too much - I get to all sorts of places on tyres; but I won't be using them on the plot.)

All best - Gavin

[Mrs Ava]

Wow John, I read all of that and understood it! However, as FoC and KenKew pointed out.....if there are so many toxins in our plassy pots, surely we shouldn't grow food stuffs in them, so the toms, peppers, aubs and squashes I am growing will be contaminated.  Also, what about grow bags - I figure as they are manufactured for growing veggies in they are safe, but what about people who are using regular compost bags - are they also harmful?  Tis a worry this living lark huh!  I quit smoking to try and live longer and not harm my kids and other people, I got an unleaded car to try and help the environment, I recycle everything I can to try and help this ailing planet, and still there are risks!  I shall be keeping an eye out for that speeding bus tomorrow  :-\

[john_miller]

Forgot a couple of things:-
  The only peer reviewed research that I have come across come across concerning growing plants in tyres was when I was checking during the discussion on the Beeb boards. I had hoped to find it again but I couldn't. What I do remember was that it was some work done by the University of California, Davis who tried growing chrysanthemums in tyres. No conclusion could be reached as so many plants died from zinc toxicity that any conclusions would have been invalid.
  The Smithsonian article was about a couple who did research into cures for cancer. The test tubes contained cultured breast cancer cells and chemicals that had shown some promise at attacking cancer cells. What struck me as significant, and the article emphasised it, was at that no time were the caps in contact with the culture solution, leading them to conclude that any promotion of cancer growth caused by the plastic came from gaseous diffusion alone, not by leaching.  
KK: as I said, we all have to make our own decisions. Perhaps do your own research? The answers may surprise you.
EJ: You have answered your own question I think? Gro-bags are indeed cleared for food production. In general, most pots (and compost bags) aren't as, I imagine, most manufacturers envisage their use for ornamentals (or compost). Again, how much is too much? The amount of lead  in pots that will be leached and metabolised is small compared to what is in the air. How much do you want to add to your, and especially your kids, intake?  Don't keep your eye out for the speeding bus too long- it's the car behind you that will get you!