Fast Food! DIY Instant Veggie Garden: Part 1

Hi Louise

Thanks for your feedback about the site and your questions. It’s great you are thinking deeper about your food gardens. Congratulations on making the effort to get them going! I’m not sure where you’re located but polystyrene wicking beds have become popular since they were promoted them on Gardening Australia. My goal is to provide useful, practical and sustainable solutions, and well-researched articles. This requires a balanced, thoughtful approach! There are some materials that are definitely off the list to use as far as I’m concerned and others, that when used correctly, may be reused as containers or used in your organic garden.

I have done a lot of research into various materials used for both new and upcycled container gardens, the environmental effects and issues, toxic chemicals, hidden dangers lurking in our gardens, growing safe food, etc and have a huge library of research material/studies/academic papers on file. I try to find research papers or credible sources that provide insight into the likely safety or risks, so I can make an informed decision. Obviously this takes a lot of time and dedication and the average home gardener doesn’t usually go to these lengths. They just want to get a garden organised and grow a few veggies! I feel obliged to do my due diligence and whilst I’m not an authority on the subject, I’m happy to share what I’ve learned in the hope of helping others make their own decisions.

Based on the research I’ve done to date, polystyrene boxes (when new and undamaged) don’t appear to be prone to leaching styrene as the mould is intact. However, it’s when you start punching holes in the box (such as to insert PVC tubing for wicking beds) that the beads become separated from the mould and my understanding is that this is how the leaching can occur. I believe the integrity of the original polystyrene mould can also become compromised if the surface is painted with some sealers (these are another subject altogether!) or if they become damaged (e.g. like my enthusiastic hubby with the whipper snipper). I’ve seen TV presenters and gardening speakers demonstrate punching holes in polystyrene boxes and I know this is not a safe practice. The styrene can be inhaled and then it is in direct contact with the soil, water, plant roots and microorganisms. Sadly, they never wear a mask when demonstrating this either, so home gardeners have no idea they could be innocently creating a health hazard.

If painting your boxes, I suggest investigating zero VOC, eco-friendly paints/sealing products. Boxes can be lined, but if lining with plastic, then you’re back to square one again! Natural materials are an alternative such as landscape fabric (can be expensive) or you can reuse natural fibres like potato sacks and hessian bags etc. There’s an excellent website where you can learn more about textiles and toxic issues called OEcotextiles. I also suggest you read the comments on my article Choose Safe Containers for Growing Food – there are many questions already answered in the comments section.

The polystyrene boxes used in my demo as outlined on this site are clean, new and undamaged. The holes in the base are already there as part of the original mould made during manufacturing. During my research, I found studies that showed acids (such as from lemon, orange and other citrus food waste) could detrimentally affect the integrity of the polystyrene mould. i.e. cause styrene and possibly other chemicals to leach. I personally DO NOT recommend making either worm farms or wicking beds out of polystyrene boxes for this reason, especially if feeding food scraps to your worms.

I know some presenters have advocated this on Gardening Australia, but I don’t know what research they’ve done into the safety of such practices. Personally, I would prefer to err on the side of caution i.e. apply the Precautionary Principle!

I’m assuming in your wicking beds, you may have used PVC pipes. If not, great! PVC is another toxic product that in my humble opinion has no place in an organic garden. And yet, it’s widely promoted on Gardening Australia segments by various presenters as the bee’s knees solution for worm towers, wicking beds and vertical gardens. I cringe. I hate seeing this because I believe celebrity gardeners who should know better, shouldn’t be encouraging people to use these materials. Problem is, PVC is cheap, widely available and an easy solution.

It takes creative thinking and a bit more effort to find safer solutions, but I believe it’s still possible. I’m not a fanatic. I reuse all sorts of materials around my garden to be sustainable, prevent them from ending up in landfill and to tread lighter on the planet. However, over the years as I’ve learned more about the toxic components of some ‘innocent-looking’ additions like car tyres, I believe the public needs to become more informed and the types of inputs they use in their gardens.

I checked out the Crommelin pond sealer you were referring to and rang the company direct. However, after speaking to them I don’t know whether that would be suitable. The technical officer did recommend an alternative, Exterior Grade Brushable Waterproofer. I asked them to email an MSDS (Material Data Safety Sheet) which should provide more insight into any possible health hazards and active ingredients. You can also request the same. All companies should provide these info sheets for their products if requested and many are online.

Grow bags are of course another alternative, as are wooden planters with pros and cons for both. See Choosing a Container – the Pros and Cons. If you have further questions, I’m happy to help you one-on-one with personal advice if needed via an online consultation anytime.

Louise, I hope this helps answer your questions and gives you some more food for thought! Kind regards Anne