It’s a common question I get asked from time to time in relation to growing food in the city for consumption, especially in the urban permaculture garden that I was up until recently managing in the heart of Berlin, tucked away behind a very busy road, and a stone’s throw away from the highway. ‘Don’t we need to be careful of contaminants and pollution levels when growing in an urban environment?’. And the answer is yes, but only to a certain degree. So what is that degree? And what should we be mindful of?

 

The realities are that sadly despite all of our development as a species, cities are pretty dirty stinky places still, with a lot of air pollution resulting from cars, factories and many other factors. The other main point to be aware of is that cities are old old old places, especially in Europe. And so it’s pretty much a given that the ground has been used for countless things before. And whether these activities created harmful residues that are still in the soil. Well, that’s something one would have to consider if and when planning an actual soil-based garden.

 

Soil based gardening

For those of you planning a soil based garden, a soil test can very quickly provide the answers to whether or not there are dangerous residues in the soil or not. But don’t fear because if there are, 99% of the time you can create raised beds in boxes, providing a barrier between your growing crates and the soil in order for your plants to be safe from contamination. For example, Prinzessinnengärten in Berlin has pretty much broken the ground in that area so to say. Creating the unique garden design concept of growing in raised beds made from crates. So no matter what state the sites soil is, the growing crates create a barrier between the plants growing medium and that of the possibly contaminated site soil it’s sitting on.

 

In the case of balconies and pot gardening

Now for those of us wanting to literally grow in the old fashioned traditional sense, and well let’s be honest most of us don’t have the luxury of having a garden to even begin forming these questions about. And so that’s where balconies and container or pot gardening really come into play in a big way. So in this case, you won’t have the concern of years of accumulated pollutant derived heavy metals and other toxic substances hiding away in your soil. No, you’re going to simply be getting potting soil and some fantastic compost for your babies and filling up your pots with fresh growing material. But of course what about pollution accumulation in this case? Many of us are aware that pollutants can accumulate over time simply through weather including dust and rain. So the question is, what should we be mindful of?

 

Heavy metal accumulation: and what to be concerned about

The truth is that sadly human Anthropogenic activities, such as agriculture, industry and urban life increase the possibly harmful heavy metals in the soil. Such as Lead, Cadmium, Ardenite and Mercury. And therefore can have an impact on the metal contents of vegetables. This is because vegetables can absorb heavy metals from both the soil and from surface deposition on the parts of vegetables exposed to polluted air, such as leaves that catch rainfall or collect dust. But the good news is that there are toxicity limits to all of these nasty heavy metals, and honestly most of the time there is absolutely nothing to worry about. Countless scientific studies have been undertaken in this area, as there was a large concern about this years ago. And it was found that toxicity levels were hardly ever surpassed except in extreme pollution cases. So the truth is that there’s hardly any reason for concern arising from these studies to cause us to worry about growing food for consumption in urban cities. If there were, let’s be honest; cities which are spearheading integrating urban gardening into their planning strategies to help increase the happiness, social well being and healthiness of their citizens, such as London, would have highlighted the risk of these ‘ventures’ very quickly.

 

 

REDUCING THE RISK

 

1. Reduce exposure:

So then, how can we minimise the presence of these dangerous accumulates in our vegetables? There are a few tricks that one could be mindful of. If you’re growing directly in soil within a garden, I would recommend a soil test for sure. Additionally, you might want to think about where your growing space is situated. If it’s on the main road with no barriers then its likely that the main carrier of pollutant heavy metals, dust, is going to permeate your soil and vegetables very easily. So one solution, in this case, would be figuring out a screen, or not growing vegetables on a balcony directly situated on a serious main road at all- perhaps grow flowers instead!

 

2. Consider what your growing:

The other thing to consider is that vegetables and fruit accumulate pollutants differently. For example, root crops, especially carrots were highlighted in one study as the main accumulator, as were blackberries. So perhaps if you’re concerned about toxicity levels and your living on the main road then don’t grow these things. Another interesting fact for urbanites is that nowadays urban planners are actively planting trees that take up and neutralise the pollutants from the air to create cleaner cities. One such fabulous species is the Poplar tree. So if you’re hunting for a new home, perhaps choose one with loads of these growing in the neighbourhood. Poplar takes up the toxins and stores the pollutants in the bark, which it then sheds at a later stage.

 

3. Get in control of your soils nutrition:

Another strategy is to ensure that your containers or soil have the correct nutrients in them for your plants to thrive and grow from. According to research if plants don’t have the nutrients that they require for growth and development readily available, they are more likely to substitute these with heavy metals. Therefore ensuring that your containers or garden has the required nutrients available in the soil is essentially a good starting point. I know this can seem like a big topic, but don’t feel overwhelmed, rather see it as an opportunity to get tor grips with the mechanisms that help your plants grow well. The soil is the starting point for everything, and there are great resources out there in the form of blogs, articles and books that can help this all become understandable.

To help you out a bit here are what I consider the main points to start with:

  1. The core nutrients to to get to grips with are Nitrogen, Phosphorus and Potassium, and then once you understand these go into the micronutrients.
  2. Try and get an understanding of what the pH of your soil is, this is going to be very handy to understand whether these nutrients are easily available for uptake to your plants or not. pH tests can be done at home very easily with test kits you can buy from garden centers or at home.
  3. To improve your soils pH and nutrient availability, compost is generally the soundest approach. Making your own can be easy and fun, but you can just as easily buy it. And if your not someone who knows a lot about this, or feels daunted by the topic, then head on down to your local garden centre, or urban garden and pick the brains of someone there. Remember though- organic is the way to go. Liquid manures can also be a very quick and easy fixer, one of my favourites being Nettle, and Comfrey (if available) left to sit and ferment in a closed barrel or bucket and then diluted 1:3 and fed regularly to whatever it is that I am growing. Also home worm farms are fantastic fun and a nice way to create nutrients from your kitchen waste!

 

Last but not least…don’t let fear stop you!

I really want to enforce, that one must not let ideas or fears over pollution stop you from trying! Firstly, if you are a naturally paranoid person, and your living on a highway, well then why don’t you at least try and grow flowers for the bees and insects to enjoy? There is also a list of fantastic plants available online that help combat pollution, to name a few: Buddleia, Camellia, Viburnum, and the maidenhair tree. Additionally, it has been noted by research that eating vegetables and healthy greens helps us to cope better and maintain healthier lives living in cities. And also…last but not least- gardening and spending time outdoors, even if on a balcony, is one of the surest cheapest and fastest ways to feel better and saner when living in an urban city. So, in that case, Happy growing!

Natasha Weddepohl

Natasha Weddepohl

From market gardening to urban permaculture projects, Natasha has been involved in a multitude of projects linked with food growing and sustainability, for over 12 years. Originally from South Africa, she has gained her experience in sustainable food production through hands-on work worldwide. She is currently based in Berlin, assisting a few projects, whilst completing an MSc in Horticultural Science.

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