How green is your garden?

29th January 2021

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Oliver Rendle

Simon Jones asks what the horticultural industry can do to reflect a changing climate

50 years after the nascent environmental movement was first awoken by Racheal Carson’s Silent Spring, highlighting the impact of pesticides on biodiversity, Simon Jones reflects on his own profession, asking what horticulturalists can do to counter the climate crisis

Because we produce and grow plants, conserve rare and endangered flora, and cultivate places of cultural, historical and scientific significance, it could be argued that we horticulturalists are all conscious of our environmental impact.

Certainly, what is not in question here are the many critically important functional roles plants play within global ecosystems; whether that be the restorative properties of plants post; fen peat extraction or sand oil reclamation in boreal ecosystems or even the role of the Saharan desert dust in providing nutrients to the tropical forests of the Amazon basin.

The horticulture industry also contributes an enormous amount to the economy, retail horticulture in Scotland contributes over £300m alone, supporting local, national and international industries within our supply chains. Plants also play a critical role within therapeutic gardening, helping people take care of their wellbeing. The industry has raised these issues to local and national government through fantastic collaborative industry led documents such as Horticulture Matters in 2014 and HTA Scottish Horticultural Action Plan in 2018.

However, once we scratch the surface, within horticulture, there are few intentionally positive environmental impacts; the main benefit being the plant absorbs carbon dioxide and provides oxygen. One can argue it is not an intentional objective to increase pollination vectors, create habitats, or improve health and well-being but we have conveniently and retrospectively used these by-products to offset the negative impacts of our industry.

Our gardens and garden centres are awash with plastic; pots, tools, machinery, gloves, cloches, fencing, membranes, sheds, fleeces, ornaments, watering cans, and more. Put this into the operational context of mechanisation, reduction of gardener resources, lack of investment and cost effectiveness and you can see why. Polymers are cheap, strong, pliable and water proof but are collectively contributing to an over consumption of finite resources and a devastation upon the planet.

Each of these environmental impacts in growing plants are, almost exclusively, linear in their embodied carbon production. They use raw materials and produce harmful waste products like GHG and effluent. The plants do have an environmental mitigation value in terms of their carbon sink or sequestration properties, although the irony is centred around the use of peat as a growing medium. In 2012, the UK used 2.2 million m3 of peat in the horticulture, most of this imported from Ireland. The UK is committed to peat reduction in extraction and use, but we will happily import it. This does not paint an honest picture of our ‘green’ credentials.

The embodied carbon footprint of 21st century living is truly mind blowing. Take the example of a red rose for Valentines Day. The 14 February in the UK does not see many roses in flower, therefore they are often transported to the UK. A single red rose has the same carbon footprint (2.1kg CO2e) as 4.5kg of bananas.

Global demand sees 250 million roses bought on Valentines Day each year with Ethiopia growing at least a quarter of them, due to its suitable climate, cheaper land and labour and less regulation. This could be held as an example of human exploitation with the negative environmental impact directly affecting the country in which the flowers are grown in terms of water consumed for irrigation and run off, infrastructure, transportation, waste produced, plastic packaging, pesticides used and fertilizer applied.

At Heathrow airport in 2017, approximately 8 million roses were imported wrapped in multiple layers of plastic packaging, distributed by refrigerated land freight, sold and kept for a few days then they are, if lucky, recycled by local authorities and composted by their specific systems. The only ‘green’ or environmentally positive aspect about this industry is the Rose (CO2/O2 exchange) in all its gloriously short lived yet globalized life! However for the four countries responsible for 98% of Fairtrade Flower production – Kenya, Ethiopia, Ecuador and Tanzania – this generates about £6 million for Kenyan flower workers and their communities a year. Workers collectively decide how to spend the money – this might go directly to them and their families, or to community services such as education and housing. The premiums can also go towards dedicated medical services to provide rural healthcare facilities. Some farms go further and provide hospital services for free for workers and their families, and subsidised care for the rest of the local population (3). Granted, it is an intertwined and complicated matter due the modern day ‘need’ for fast cheap production and if we stop the demand what then happens to the people and their livelihoods at the production source? Alternatives are required and perhaps the horticultural knowledge gained by local people could be focused into growing food crops within their countries rather than servicing affluent nations with roses. In addition, profit throughout the supply chain could be redirected into enforced mitigation of the production impacts like the EU polluter pays principle (17).

When considering tree planting as a commonly acceptable urban climate change mitigation measure, it is prudent to assess the multiple correlation issues of embodied - production and operational carbon - when considering nursery grown trees. Urban trees do indeed mitigate climate impacts by assimilating carbon dioxide (CO2) in their biomass as they grow and, through shading, evapo-transpirational cooling and wind speed reduction thus reducing building energy use. (8) A 2011 study at the University of California stated that urban tree production GHG emissions were modest in comparison to the carbon sink effect of the tree, within its life span. This is very positive and takes into account the GHG emissions from the energy, irrigation & fertilizer use in the trees’ production. However, my point is that the horticultural component of this process is the part which has the negative environmental impact and if these processes are disrupted to have a lower impact then the carbon sink effect of the trees will have a conversely greater positive value to the environment. The intriguing addendum to this discussion would be the, ever more important, biosecurity concerns in the moving of organic materials across or between countries, a direct impact of this is witnessed by the rapidly declining numbers of ash trees in the UK, now suffering from ash die back, which can be directly attributed to globalised tree production methods. This further emphasises that the horticultural industry component of this situation should be disrupted so that the trees are raised from seed to whip, locally, thereby reducing the risk of transferring pests and diseases (20).

Globalised food crops, in particular, often travel huge distances, but can they be produced more locally in an almost bio-regional manner (12) whilst disrupting the systems that ensure food lorries account for over a fifth of all traffic on our roads with the top 5 food retailers having an annual turnover of £30bn, utilising land in which 0.5% of citizens own almost all of the land in the UK (12). This does not give the impression of food security, more like food insecurity and risk, with most of that food only ever stored in freight lorries rather than warehouses such is the immediate demand generated by our consumerism. These figures become even more mind blowing when we factor in that the UK, USA and Japan wastes at least 50% of all food purchased! (18) Plant consumerism is almost analogous to the supermarket supply chain model i.e. we want it now, fresh and sometimes out of season, even in horticulture we bear witness to our 21st century conditioning. It seems obvious that a rethink of our food (in)security on a local, national and international stage is urgently required. The subject of food insecurity is not a foreign issue and the lack of produce on our shores will become greater with the National Farmers Union stating that by the mid 2040’s the UK will only be able to feed 53% of its population (4).

With food insecurity in mind, horticulture must face of climate change, in my opinion, undertaking a radical shift away from the importance of established gardening resources used to conserve traditional gardening practices to resources being refocussed into; local food production, flood mitigation, clean air generation, habitat creation, contaminated land regeneration and organic waste recycling (vermiculture and not heavy industry).

Please note that I am in no way suggesting that the fantastic skills and plant collections within Heritage & Botanic Gardens are refocussed in this social manner. Their plant and seed collections will become, and already are to a large degree, ex situ refugia for currently rare and endangered plant taxa from across the globe. The global collective of atavistic botanical knowledge will be critical in understanding suitable plant choices in the face of a changing climate and as such these prize garden assets may need to continue diversifying and integrate in order to directly help society. Where does this change begin? Education!! The inclusion of horticulture into our national curriculum is the key, taught from primary school through to secondary school, and beyond, with its importance being akin to reading and writing. Nelson Mandela once said, ‘Education is the most powerful weapon which you can use to change the world’…this is not ideology…the next generation are demanding it.

The growing of plants is inextricably linked to the state and fate of the modern world, the history of which can serve as an educational platform learning from despicable human inequality and persecution, none more obvious when considering the impacts of the stories surrounding; tea, tobacco, sugar, opium, quinine and cotton; shaping the destiny of countries and industries around the world (11).

We must be able to augment collective will, thought and professional disciplines with the absolute need for change. I am suggesting that a ‘National Framework for Sustainable Horticulture’ is created that primarily focuses on three aspects;

  1. Horticultural education in the national curriculum
  2. Integrated approach to being carbon neutral in all plant production including food crops
  3. Use of practical horticulture to address social issues in modernity

This pragmatically realised by an honest non-political approach, harnessing the knowledge disseminated through hundreds of years of agricultural & horticultural expansion that is currently taught and fine tuned into our students. The horticultural industry can ensure future generations possess the ability to grow plants, mitigating the risks of food insecurity and play our part in what Tim Lang calls the ‘Great Food Transformation’. Horticultural skills and knowledge are part of the solution to complex societal issues in a changing climate.

Simon Jones is gardens and designed landscapes manager at National Trust for Scotland


  1. Berners – Lee, M. How Bad Are Bananas – The Carbon Footprint of Everything (2010)
  4. HTA Scottish Horticultural Action Plan, page 8, 15
  5. Alexander, P. Peat Use and Environmental Concerns, RHS
  6. Clifton Bain and Emma Goodyer, IUCN UK Peatland Programme, August 2016
  7. Sherman, R. The Worm Farmers Handbook, Mid to Large Scale Vermicomposting for Farms, Businesses, Municipalities, Schools and Institutions, 2018
  8. Kendall, A & McPherson, E. G, A life cycle greenhouse gas inventory of a tree production system, (2011)
  9. Transform September 2020 Edition – Article ‘In conversation with John Elkington’
  10. Thackery, F. Plastic Free-Gardening, (2019)
  11. Musgrave, T & Musgrave, W – An Empire of Plants – People and plants that changed the world. (2000)
  12. Lang, T. Feeding Britain -our food problems and how to fix them, (2020)
  13. Edited Vitt, D & Bhatti, J, Restoration & Reclamation of Boreal Ecosystems – Attaining Sustainable Development (2012). Pages 179-203
  18. Stuart, T. Waste – Uncovering the Global Food Scandal, (2009)
  19. Frediani. K. (2009) The ethical use of plants in zoos: informing selection choices, uses and management strategies. International Zoo Yearbook. Volume43, Issue1 January 2009 Pages 29-52
  20. Frediani, K. (2020). Botanic Garden Profile Inverewe: gardening on the edge. Sibbaldia: The International Journal of Botanic Garden Horticulture, (18), 19-35.

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