On a sunny Saturday morning at Windmill Hill City Farm, as I shoveled compost with my fellow volunteers onto the vegetable patch we were creating, our conversation turned to plastics.
Sitting on the dirt, waiting to be planted out, were upwards of 20 kale seedlings in a black plastic plug tray. In the greenhouse, hundreds of plants were germinating in similar containers. “The horticulture industry has a lot to answer for”, concluded one volunteer, who had previously worked at a commercial gardening centre.
So it was that the seed of my investigation began to germinate.
A growing problem
Plastic is now ubiquitous in horticulture. From trays and tubs to pots and propagators, the material has replaced much of what was long ago made from terracotta, clay and wood. Being light-weight, water resistant, durable and cheap, plastics have proved convenient both for nurseries and the gardener.
An estimated 500 million plant pots and seed trays are sold in the UK every year, making this aspect of our plastic consumption one that demands more attention – yet so far it seems to have escaped scrutiny. It is perhaps not shocking to learn that two thirds of these pots end up in landfill or incinerators.
The lives of many pots do not extend long past their journey home from the shop. The supply of plastic pots from buying new plants often exceeds what a gardener can use – despite the culture of re-use amongst green-fingered enthusiasts. The scope for re-use is limited by the need to clean pots between uses in order to minimize the spread of disease, and their habit of becoming brittle and breaking over time.
Few council kerbside collections accept unwanted plastic plant pots for recycling, as they are typically made from black high-density polyethylene (HDPE) or polypropylene (PP). Indeed, Horticulture Weekly found that only 9 out of 75 local authorities sampled had a recycling scheme for plastic garden waste.
At the commercial scale, recycling and reusing pots has proved financially unviable for some nurseries, particularly small ones, due to cleaning and disposal costs. Even some larger garden centres have ceased their take-back services, referring to difficulties finding national re-processors with the ability to handle the breadth of different plastics used in pot manufacturing.
Gardeners have not been immune to the plastic-free zeitgeist which has developed in the past year. In a survey conducted by the BBC’s Gardener’s World magazine in 2018, three quarters of the readers surveyed thought that the amount of plastic in gardening was a problem. Whilst 41% acknowledged that they had a personal responsibility to tackle the issue, the majority believed that manufacturers should be responsible for reducing the use of plastic in gardening.
Taupe is the new black
So how is the industry changing? One solution from manufacturers has been to design plastic pots for recyclability. Enter, the taupe pot – made from a high percentage of recycled PP and free from the carbon black pigment that creates issues for sorting technology in recycling plants.
This plastic alternative has been taken up by the Royal Horticultural Society (RHS), which has struck a blow for sustainable procurement by specifying taupe or blue pots from its suppliers. It is worth noting that guidance from the Horticulture Trade Association (HTA) states that such pots are around 25-30% more expensive to produce, resulting in a 1.5-2% price hike for the would-be plant buyer. However, the Gardener’s World survey found that nearly three quarters of respondents would be willing to pay more in the future to cut their plastic waste, so perhaps the extra cost won’t be too off-putting.
Local authority collections, however, remain a problem. To address this, the HTA is working with RECOUP, the plastics recycling charity, to inform local authorities, waste processors and consumers about taupe pots. The HTA Nursery Working Group is campaigning with companies like Viridor to ensure local authorities accept non-black plant pots in kerbside recycling. The HTA has also established ‘Ecogen’, a national collection scheme enabling members to send trays and pots for recycling, and is working to get approval for the recycling symbol to appear on taupe pots.
Potty ideas
This spring, the RHS ran a sustainability workshop in which the topic of biodegradable alternatives to plastic was debated. I spoke to Tim Upson, the society’s Director of Horticulture, to find out more about their pros and cons.
Generally, these consist of two types: pots intended to be planted directly in the soil and to break down quickly; and those meant to last for a number of years.
One popular material is coir, which is made from coconut husks. This is fairly waterproof, while being beneficial for the root development of seedlings – and is already commercially available from The Hairy Pot Company. Although good for short term crops, coir may not be robust enough for larger or longer-term planting.
Another biodegradable is the ‘Ecoexpert’ tray introduced by Modiform, a horticulture packaging firm. These are made from recycled paper. On the other hand, bamboo pots, like those made by Haxnicks, are much more durable.
Upson highlights that the issue with biodegradables is that they need the right conditions; “Biodegradable pots – you plant and they either degrade too fast, or not at all”. Wooden trays can also breakdown too quickly or harbor pests and diseases as they can be difficult to clean.
Pot stand: a wide range of alternative to plastic plant pots is now available. Photo: Hannah Gillie.
These are not the only problems with biodegradables: as Upson points out, “there is a large carbon footprint potentially associated with these products”. Both coir and bamboo are primarily sourced from south Asia, which raises a host of environmental considerations, not least regarding the resources required to transport the products halfway across the globe.
Another alternative is far more traditional: terracotta. Last year, the Urban Jungle nursery in East Anglia announced a plant range grown and sold in terracotta pots. They are sold at a premium, but customers receive a rebate if they return the pot, making it something of a deposit refund scheme.
Guidance has also sprouted on how you can reduce your use of plastic pots at home. Suggestions include making your own out of newspaper or toilet roll holders, although with gardeners generally having a lot of old plastic pots to hand, making your own alternatives seems a little unnecessary. It is also unlikely that making your own pots will be viable at a commercial scale.
Do home-made plant pots have a roll? Photo: Stacie / girlingearstudio (CC BY 2.0), via Wikimedia Commons.
Garden tools
The research and development going into alternatives is certainly positive, but none stands out as ideal. So, instead of changing the material, can we change the business model?
“The core of it is returning plastic to being a tool and not a disposable tool, but a tool which is valued,” says David Ware of Edibleculture. The Edibleculture nursery, located in Faversham, Kent, has declared 2019 to be a ‘plastic year zero’, in which they aim not to sell any single-use plastic products or packaging. The nursery has trialled growing seeds and cuttings in coir, earth blocks, cow dung and wooden pots, but none has proved commercially viable. Instead, they re-use plastic pots, as well running an in-house recycling system. They wash and sort the plastic pots themselves, shred the plastic and either sell it back to manufacturers or give it to a local school where it’s used as 3D printing filaments.
“Our argument is very basic,” says Ware. “You’ve got reduce and reuse, and then at the very end, only if you have to, recycle.”
Their shift in practice has proved popular with buyers. “We’re taking responsibility for our own plastics and it’s something which customers are really liking,” explains Ware.
However, there are challenges still to be faced. “We’re taking the financial risk because we can as a small company, but the important people, the people who are supplying garden centres and supermarkets, are just going to do it so slowly.”
However, some of the bigger players are starting to switch. The National Trust and Waitrose have both moved away from the predominant paradigm of single-use horticulture, while the RHS has introduced a Plastics Policy. Government, too, is starting to pay attention, having held a debate on plastics in agriculture in November 2018, while the recent Resources and Waste Strategy provides an overarching framework in which targets are set for minimizing plastic waste.
The combination of consumer pressure, Government action and innovative products and practices suggests that it should be possible to all but eliminate single-use plastic plant pots, and give the horticulture industry a lot less to answer for.
We all just need to put our shovels in the soil and make it a reality.
Featured image: Symphori, via Pixabay.
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