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Growing local


Garden hazard_1

Tyres may seem handy to grow food in but they are one of many health hazards found in school gardens.

There’s a lot to consider when setting up a new garden – what soil to use, which plants to grow and how to maintain the garden. But just as important are the type of materials you use to build the garden and prepare the soil, especially when it comes to the health of your garden and students.

Car tyres can leach cadmium and other heavy metals into soil as they weather and should never be used for garden or compost containers. If your school is using tyres as food growing containers, you could keep the tyres in place for growing non-edibles but grow food plants in uncontaminated soil.

Treated timber is not recommended to be used as edging for garden beds in schools due to concerns about the leaching of chemical products, including arsenic (a known carcinogen), in the treated timber onto the timber surface and into the soil. Some alternative timber preservation methods contain pesticides, while others leach copper or boron and also are not considered appropriate in school gardens.

Natural fibres in carpet and carpet underlays are treated with persistent pesticides and many carpets contain toxic chemicals. If used to cover or suppress weeds, when exposed to the elements, chemicals from these products can leach into garden beds, compost and worm farms. Thick weed matting can be used to suppress weeds and if you are building a no-dig garden, see Curriculum Materials – Topic 3, From the Ground Up for information on preparing the ground to make an ‘instant’ and easy garden.

Getting manure from a local farm or racetrack?

Garden hazard_2When it comes to preparing the soil for planting, it’s wise to check the origin of the compost or manure. Make sure the compost does not come from pastures sprayed with pyridine herbicides and that manure is not from animals that have grazed on sprayed pastures. The herbicide remains active in both the mulch and the animal that has grazed on sprayed pastures until the chemicals are broken down by microbes. To avoid herbicide and general hygiene risks, use only well-rotted manures broken down through aerobic composting or purchase compost registered for use in organic farming or gardening. For composting methods and activities, see Curriculum Materials – Topic 2, Living Soil.


Herbicides should never be used to clear the garden area of weeds or other vegetation as they kill or inhibit a range of soil organisms, increase the incidence of soil-borne diseases and impact on the health of soil, humans and other animals. Many shelf-bought herbicides contain an active ingredient called glyphosate, a toxic weed killer linked to non-Hodgkin lymphoma, and other ‘inert’ ingredients linked to human cell death, particularly embryonic, placental and umbilical cord cells. Be sure to check if your school is using these products on any part of the school grounds. Organic weed control uses physical methods such as weeding, mulching and grazing, and also the use of safe products registered for use within organic systems.

Australian Organic Schools is compiling a list of safe products to use in organic gardens so you don’t have to worry about whether you are buying something that’s bad for your health. See Garden Products for more information and if you have a favourite product registered for use in the organic garden, please email to see if we can add it to the product list.

Click here  to read about the how the Australian Certified Organic Standard outlines the minimum requirements for certification of organic or biodynamic produce and takes a whole-of-system approach to the health of people, animals, plants and soils. This is a good resource for making sure the products you use in preparing and maintaining the garden won’t compromise the health of your garden and students. When you see the Australian Certified Organic Bud logo on a product such as organic compost, you can be reassured that its product ingredients have been certified to the Standard and have met rigorous certification checks.

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Quite a good little article. While aimed at creating safe school gardens the information applies to all home gardeners.

There's a link to organic garden products which includes compost, seed outlets and more.

leeching chemicals are the least of my worries...... I'm more concerned about everything else in my garden trying to kill me! Bougainvillea, bromeliads, spiky saw blade palm tree fronds, rose thorns, brown snakes.....I could go on all day!

Controversial Andy strikes again...

I think we worry too much.  Fair dinkum.  Remember the article from one of the councils proving treated sleepers were okay (unless you spent a few weeks licking them)?  Frankly, everything these days will kill you - peanut paste, bread and the list goes on.  Use some common sense, that's what I say.

You know the biggest risk from tyres?  One will hit you - with a damn car attached.  LOL. 

And leeching?  I'm more worried about my kids' leeching than my sleepers. 

It's all a matter of personal choice of course.

Personally, I've read enough to begin to realise that there are way too many chemicals introduced into our food system already and it's affecting humans in all sorts of insidious ways which aren't obvious at first glance without me introducing more into my garden (or school garden which is where the article has come from) in any form, including old tyres or chemically treated sleepers.

I would love to be completely chemical free ie organic. Bit of a pipe dream in this day and age of love thy chemicals and that includes plastics.

A stronger version of Roundup has just been registered and approved by the APVMA, normal Roundup contains 360g/L glyphosate, the new stuff contains 520g/L glyphosate. 

Product Name:
Roundup Dura Herbicide By Monsanto
Active Constituent/s:
520 g/L glyphosate (present as the potassium salt)
Applicant Name:
Monsanto Australia Ltd
Applicant ACN:
006 725 560
Summary of Use:
For control of many annual and perennial weeds
Date of Registration:
31 March 2014

Getting ready for more "Roundup Ready" GM crops?.  Some sorghum crops are now being defoliated by Roundup, prior to harvest.  The poison is actually sprayed on the crop, not the weeds, so that residue is getting into your chook food.  The only way to stop all this is to pay more and buy organic - everything. 

I just found out that the sorghum spray is Roundup Ultra Max, which is even stronger at 570g/L glyphosate.

Birdy num-nums indeed!

My Mum always used that expression, birdy num-nums :)

I used to use glyphosate every now and then. I've done more reading since then and the product scares the be-jesus out of me. Along with GM products the more I read about them.

I have some Zero Super Concentrate :( bought in desperation a time back. It's been used to kill a small test portion of a patch of bamboo that I'm trying to eradicate. It worked too. Nothing else does. But I've not been game to use any more of it due to it's toxic nature.

I was one of Roundup's best customers :-( Used it repeatedly around the fence line to keep the footpath grass from invading my non-grass yard. After a few years the soil which was sprayed grew nothing at all. And the odd grass stolon which ventured across the minefield grew huge in comparison to normal grass. And 'they' say it does not harm the soil! Huh!

After all the excitement about the styrofoam self-watering box system at Spurtopia, I had to do some reading because I could not shake the feeling that it is not right to grow food in polystyrene, besides the fact that it looks quite ugly. It turns out it is quite toxic and yes! leeches chemicals in the soils. I can't afford expensive pots. For me it defeats the savings from growing my own food so the brain has been ticking since this major disappointment and I am working out a new system where the polystyrene does not touch the food, soil or water. I figure if I use upside down box to hold the pots above water (Kratky style) over the top of another container to keep the water from evaporating and use old bits of sheet as wicks for those plants, which don't grow big roots. (just lost my oregano which should really grow like weed) I think I'll start a separate discussion about non toxic container once I finished my prototype.

Oregano likes dry conditions with perfect drainage - as do Lavender, Rosemary and Pennyroyal. Hmmm, didn't know about the styrene leaching toxins - yecch. I use sheets of styrene inside my bins to shield the roots from heat. I'm interested to know what your research and experiments reveal.

Thanks Elaine. It seemed to die from drying out completely :\ I think I might rehouse the survivors in the normal beds. 

I thought I should mention also that polystyrene in the heat is definitely not good either. I plan on covering mine with the rest of the old sheets or jute bags.

In an earlier version of our garden here, we used Styrene boxes. Elaine painted them on the outside using 'water paint' or 'plastic paint' which kept them from breaking down quite so soon and made them look a little less like ex-fruit boxes. Perhaps the same paint - or a more natural paint - could be used on the insides. Oil paint dissolves the Styrene so I hear. Whether natural paints are oil-based I don't know.

Putting old sheets inside the bins before filling them with mix sounds like a quick and simple solution.


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Vetiver grass helps to stabilise soil and protects it against erosion.  It can protect against pests and weeds. Vetiver is also used as animal feed. (Wiki.)

GrowVetiver is a plant nursery run by Dave & Keir Riley that harvests and grows Vetiver grass for local community applications and use. It is based in Beachmere, just north of Brisbane, Australia.

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