You may have heard that the Horticultural Trades Association (HTA) recently brought in ‘taupe’ pots – actually a kind of bilious shade of grey – as an alternative to the ubiquitous black variety which can’t be recycled as sorting machines don’t ‘see’ the colour black.
Taupe pots use a polypropylene completely free of the ‘carbon black’ pigment, so sorting machines should be able to see them and recycle them along with other rigid plastics.
The work goes on to encourage garden centres and nurseries to take up the taupe pots: it’s always been a given that this is going to arrive on shelves gradually, as the current stock of black pots has to be used up first. Fast-growing plugs, like bedding, annuals and vegetable plugs should appear in taupe first, followed by perennials, followed by shrubs and trees which are in containers for longest.
So far Hillier have led the way by having its first commercial crop ready grown in taupe, Other growers are following; Waitrose already has plants in taupe pots on the shelves, and Wyevale Nurseries, Farplants and Bransford Webbs are among other names taking up the new pots. They will be more expensive (of course) but the (smallish) cost rises aren’t expected to appear on plant price tags till 2020.
For the taupe pot initiative to succeed, they have to be not only recyclable, but actually recycled. And there’s the rub.
But trade magazine Horticulture Week took it upon itself to ring 70 local authorities and actually ask them whether they will accept plastic plant pots in kerbside collections.
61 of them – that’s 87% – said they would not accept plastic plant pots at all, whatever colour they were.
The advice is to drive your plastic plant pots to your nearest municipal tip for recycling there (as long as they accept rigid plastic themselves, and as long as the pots are not black, of course). For me, that’s a 1hr 20 minute round trip to Exeter. Which rather cancels out the environmental benefits of recycling the pots in the first place.
The HTA is now lobbying the government to put pressure on councils to accept plant pots alongside rigid plastic food packaging and take them for recycling.
But I can’t help thinking that this underlines the increasingly undeniable fact that recycling is not the answer. It is, at best, the least we can do: but it’s a half-hearted, lily-livered sort of an attempt to turn back the plastic tsunami which floods into our gardens each year.
Even recycled plastic still ends up in landfill or floating about in our oceans anyway: you can only recycle plastic 7-9 times before the fibres become too short and they are useless for recycling further. And that doesn’t even start to address the 70% or so of rigid plastic which is not recycled at all, by anyone, whether there are the facilities to do so or not. And that’s a lot of plastic: there are 500 million new plant pots manufactured every single year.
The only real solution is – as so often – the less easy one that requires real, genuine change. We need to find other ways of doing things which don’t use plastic at all – not even if it’s recycled. Wood, metal, paper, cardboard: materials which biodegrade at the end of their lives, properly, without harming wildlife or polluting our environment. That is the only real way out of this mess: anything else is just a sticking plaster covering more of the same old rubbish.
Probably the one type of biodegradable plant pot we’ve all used at one time or another, clay pots have a fine pedigree: they were the go-to pot of choice for all Victorian estate gardeners, and remain the benchmark for classy gardens everywhere.
What is it: Clay pots are made of baked clay – that’s the stuff you get out of the ground, so about as natural as it gets. As old as the hills, the ultimate in traditional gardening, they look wonderful and last for ages if you look after them. But they are heavy and clumsy gardeners will struggle to keep them in one piece.
How long do they last: Theoretically, forever; you can reuse clay pots year after year for generations. They are more robust than plastic pots, in that you can strim a clay pot without it getting shredded; but if you drop one, you’ve lost it.
How are they made: You’ve seen Ghost, right? You know the pottery scene? (of course you know the pottery scene; it’s the only one anyone remembers from that movie). That’s basically the same for plant pots. Except possibly minus Patrick Swayze. They are made, by hand, from clay, on potters’ wheels, then fired in a kiln. You can watch a rather lovely video of US master potter Guy Wolff making terracotta pots here.
Terracotta – literally ‘baked earth’ – just refers to pots made of unglazed, and therefore porous clay (as opposed to ceramics, which are glazed).
Cost: Middlingly expensive, at about £1 a pot for 11cm diameter; slightly cheaper from reclamation yards where you can get lucky and pick up boxes of second-hand clay pots relatively cheaply.
Also available as: Rhubarb forcers, plant labels, plant saucers, pot feet
Pros: Re-usable and long-lasting; heartbreakingly lovely to look at, the stuff of fantasy gardens everywhere. They age beautifully, too. Available in every possible size and shape, and readily available too; these are the one type of biodegradable pot you can be sure to find in a standard garden centre. In my experience, plants like clay pots and seem to grow better in them: I think this may be because their porous nature allows the roots to breathe a little better. They dry out quicker than plastic, but re-wet more thoroughly as the pot absorbs water as well as the plant, so you don’t get water running down between rootball and pot and draining out at the bottom without wetting the roots. There are many UK based manufacturers, so they don’t have to travel far to get to you; though watch out as the cheaper versions seem to be made by a company called Spang, based in Germany, so are imported and so have a higher environmental cost.
Cons: Heavy, and easily broken. Pricey, especially online mail order as the postage costs are high for heavy items. The firing process – 1000 degrees for 18 hours or so – means that even though they are produced locally so don’t have a high mileage, the carbon footprint of clay pots is still pretty high.
Stockists: Widely available from garden centres, reclamation yards and garden equipment suppliers online.
UK-based terracotta pot specialists include Yorkshire Flowerpots and Whichford Pottery . Both do a ‘garden essentials’ range, but expect to pay more; there’s a good reason, too, as these are superb and very beautiful pots, and a cut above your bog standard potting shed fare.
Coconut fibre (coir)
The second most commonly found biodegradable alternative to plastic after clay; a single-use biodegradable which the plant roots can grow through, so you plant it along with your seedlings. It’s also made from what would otherwise be a waste material. Unfortunately, because it must be imported from south Asia, it comes with quite a high environmental cost.
What is it: Coir is a by-product of the coconut industry. It’s that fibrous, hairy stuff you find on the hard shell of a coconut, a mix of lignin and cellulose, and it’s extremely useful stuff: it’s also used in ship’s rigging, matting (mainly door mats) mattresses and potato sacks. It is, unusually for biodegradable materials, relatively waterproof which is what makes it such a popular product in horticulture.
How long do they last: Up to 12 months above ground before they go ‘hairy’ and are best planted in the ground. There they take a few months to biodegrade.
How are they made: Fibres are stripped from the coconut then softened in water, then mixed with latex, the sap from rubber trees, before being moulded into pots.
Cost: 50 9cm pots for £11 (but need to buy new each year)
Also available as: Hanging basket liners
Pros: Easy to re-wet as absorbs water easily. Available in every size from Jiffy propagation modules to large pots. Can be planted out in the garden without removing from the plant, avoiding root disturbance.
Cons: Coir has a high environmental footprint as it must be shipped from coconut-producing countries like India, Sri Lanka (between them the producers of 90% of the world’s coir supplies) and the Philippines, with all the carbon emissions that entails. And because these pots are not meant to be removed from the plants but are planted out with them, you have to buy in a new supply each year. Commercially, coir pots are often sold wrapped in plastic.
Stockists: It is surprisingly difficult to find larger coir pots. Small ones – propagation modules and pots up to 8cm – are readily available and the biodegradable pots you’ll most often find in garden centres. But I don’t use 8cm pots; I jump from modules to 10cm as I’ve found they need less watering, and anything below 8cm I can make myself at home. I did however find two UK sources for larger coir pots:
OK so you want to replace the plastic pots in your garden? Here are the first of many options available to you (I’ll be going into detail on about 10 different materials over time; once I’m done you’ll find the full list on the Plastic Substitutes page).
Prices given are for 4″ (10cm) pots, just because it’s the size I use most; any smaller, you can make yourself more easily and more kindly to the environment at home (see Plastic Free Gardening to find out how).
One of the most useful natural materials on the planet, bamboo is harder than oak, and doesn’t swell or shrink like other woody products. In other words; it’s a great material for making plant pots.
What is it: If you’re not keen on the whole rustic terracotta schtick this is the one for you. It looks so much like plastic it really ought to be plastic – but it’s not, it’s biodegradable bamboo masquerading as plastic, funky colours and all. Great if you want a modern, sleek look; not so great if you’re after a practical solution to your potting supplies as the range is very limited.
How long do they last: 2-3 years
How are they made: Bamboo pots are made by mashing up the bits of bamboo left over from making furniture and so on and moulded into pots using binding agents – usually resin, or cornstarch – heated and pressurised to form the final shape.
Cost: £2 per pot for the high-end of the range; more usually around £3.99 for a set of five
Also available as: Plant labels
Pros: Looks and behaves the most like conventional plastic, and comes in a range of colours. Reusable, so you get good value for money.
Cons: Exceptionally difficult to source, and the range of sizes seems to be very limited – usually either 8cm or 13cm, the exception being the hybrid bamboo/rice husks/straw Biopots which do offer a good range. Very expensive (although to counter that, bear in mind that these can be used over and over so aren’t really comparable to single-use biodégradables). There is a company in China called Ningbo Frontier Plant Fiber Products which appears to be the main wholesale supplier, suggesting these are usually imported from the other side of the world – giving them a high environmental cost.
Stockists: Jpots specialises in bamboo pots but I’m not sure whether or not they’re still trading. If so, they also claim a minimum 4-year lifespan – a year more than most bamboo pots.
Homeleigh Cornwall/Devon based garden centre stocking bamboo fibre pots, but 8cm only.
Greentones sells plant pots made of a combination of bamboo, corn starch, and rice husks.
Biopots made from bamboo, rice husks and straw. Grower pots range in size from 2½ inches up to 8 inches. The lifespan is one year outdoors (planted) and three years indoors (planted).
Cardboard, cellulose and paper
I love my little home made newspaper pots; I also save cardboard loo roll inners for sowing broad beans, sweet peas and the like. So I’m already sold on the idea of cardboard and paper growing. Turns out it’s one of the most promising materials for larger pots too.
What is it: Cellulose, from which cardboard and paper is made, is basically the woody fibres you get by mashing up plants. So cardboard, paper and cellulose itself are organic, biodegradable materials which readily decompose in a compost heap. They are also rigid enough to hold plants, so an obvious choice for making pots. These are single-use biodegradables; the plants grow into and through the pots and you plant them both out together.
How long do they last: About three months once planted
How are they made: You can actually make your own cardboard pots from ordinary cardboard boxes; all you need is a template and a stapler to hold the things together. I feel a how-to coming on…. Not right now, though, that’ll have to wait till I’m feeling a bit more Blue Peter ish.
But commercially available cellulose pots are made from newspaper and cardboard that is then shredded and mushed with water into a pulpy mess. This is then mixed with adhesives – usually resins – and binders before being shaped over a mould and dried. Note that the resins and binders may be natural or synthetic – and if they’re synthetic, that means non biodegradable plastics.
Cost: £11 for 12
Also available as: Hanging basket liners, plant carrying trays
Pros: As with all single-use biodegradable pots the plants grow through the walls of the pot, so there are no problems with root disturbance or plants getting pot bound. They therefore establish much more quickly than when grown in plastic pots. Cellulose is also a readily found material which has a very low carbon footprint especially when made by recycling paper and cardboard, and is locally sourced more or less wherever you happen to live in the world. Cheaper than most biodegradable pots too.
Cons: Paper and cardboard has a mould problem. After about three months the pots turn an unappetising shade of green or white and fluffy, neither of which is particularly pleasant. I know from my own experience with toilet roll inners that they can also sport quite large mushrooms too. These don’t seem to do the plants any harm and are easily picked off, but they aren’t pleasant to deal with. This is only a difficulty above ground and normally once planted these problems disappear, but it’s the main reason you don’t find cardboard pots on plants offered for sale in garden centres. Also the binding agents used to make cardboard pots are often synthetic (i.e. plastic) – so unbiodegradable. Look out for ‘fully biodegradable’ on labelling. If you don’t make your own cardboard pots they are usually imported, so come with relatively high carbon emissions, though not as high as other types of biodegradable pot imported from China and the US, as most cardboard pots available in the UK come from mainland Europe.
Romberg: A German company but the only one I could find making cellulose pots readily available in the UK, mainly via Ebay and Amazon. There doesn’t seem to be a central point where you can buy these but they are quite easy to find. Available in 11cm diameter pots; 8cm diameter and smaller available from www.gardencentrekoeman.co.uk.
Look out too for the EcoExpert range of cellulose pots from Modiform, currently under development: they are aiming for the wholesale market but could find their way into garden centres too.
Not available in the UK:
Kord Fiber Grow developed using recycled paper. Unfortunately I’ve been unable to find a stockist here in the UK: they seem to be mainly US and southern America, with one stockist in Germany.
Grow Organicdo pulp pots made of recycled newspapers: but again, an American company (I am beginning to think I would find this a lot easier if I lived in the States).
Western Pulp: Fibre pots in a huge range of sizes, including some quite large, available through www.greenhousemegastore.com. The larger ones however are kept rigid using asphalt emulsion, which sounds awfully like a petroleum based product to me, so not that different from plastic really.
Ellepot is a Danish company which makes paper sleeves for commercial propagating, a bit like a Jiffy 7 but made of paper and you flll it yourself.
Smaller pots – anything up to about 7cm – are easy. You can make them yourself: save your loo rolls, make newspaper pots, or use a soil blocker. Small plastic pots and module trays were the first things I got rid of in my garden: I no longer use them as I find the alternatives so much better. I’ll be detailing how I did it soon on this very blog.
Larger pots, though, are tricky. You can’t make them yourself: so you have to buy them in. And most of the pots you’ll see offered for sale at sizes 10cm and above are plastic.
That’s not to say there’s no alternative to plastic pots: actually, there are loads, they’re just quite difficult to find. The stranglehold plastic has over the horticultural industry is loosening off, just a teeny bit, and most garden centres now sell at least some biodegradable pots. But if you look into it more closely, the choice is actually quite bewildering. I have found just under a dozen different biodegradable materials currently used as a replacement for plastic in gardening products. Here’s the list:
coir (coconut fibre)
Some of these sound like they might be the same thing, but nonetheless – it’s quite an impressively varied choice.
Why we are still using so much plastic when there are so many other types of pot out there I’m not entirely sure. Part habit, I’m sure; but also because biodegradable pots are definitely more expensive. This is mainly because most biodegradable pots, ahem, biodegrade; so they don’t last very long and need replacing each year as they are planted along with the plant. That’s not the case with all of them, though: clay pots are the obvious example of a long-lasting biodegradable pot, and there are others which claim a life of at least 3-5 years.
The clincher for me, though, and one that justifies the extra expense is that quite a few biodegradable pots are an improvement on plastic. When plant roots can breathe (as they cannot in plastic), when they can grow through a material rather than being forced to circle round and round (pot-bound plants are a thing of the past when you grow in many biodegradable pots), and most importantly of all when container and plant can go into the ground together with no need for root disturbance – that means a happier plant that’s more vigorous, healthier and quicker to establish in the garden. I can bear witness to this myself: my results, especially at the beginning of the year when I’m sowing, pricking out and transplanting hundreds of plants, have noticeably improved since I stopped using plastic.
Not all these advantages apply to rigid biodegradables like clay or bamboo, but you still keep some. I find when growing in clay pots that the plants seem to appreciate the increased exchange of air and moisture through the sides of the pots, and though they dry out more quickly they also wet more thoroughly than plants in plastic pots, as the clay absorbs the water as well as the compost. That means you don’t get that effect of water running down the sides between rootball and pot before draining out the bottom and leaving the roots as bone dry as if you hadn’t watered at all.
The more I grow in biodegradable containers the more I like it. But having tried a few different types in a rather haphazard way over the last few years, I’m also aware that they are not all alike. There’s a big difference between growing in a floppy coir pot and a rigid terracotta pot; and there are other considerations too. Rice hulls have a very different environmental footprint to cow manure, for example.
So I am going to be spending the next few weeks collecting together information about as many of the biodegradable alternatives out there as possible. I’m also going to get my hands on a few samples of the pots in question and put them through their paces. The result, I hope, will be the most comprehensive analysis yet of exactly what it’s like to grow your plants in non-plastic materials; which are the best, which don’t perform so well and which you should be using in your garden.
So far I think I’ve established that your ability to dispose of the plastic in your garden responsibly kind of depends on where you live. You may be in the lucky 49% of the UK whose council collects rigid plastic from the kerbside. Or you may have one of the UK’s rare plastic recycling plants in your neighbourhood, in which case your local garden centre may have set up a pot collection scheme in partnership with them.
Unfortunately neither of those applies to me: so I’m stuck with trundling 30 miles along the A30 to Exeter and back to visit my nearest big city tip if I want to recycle my surplus pots.
Unless, of course, I avoid recycling them altogether and just pass them on.
My stockpile of plastic pots is perfectly serviceable: there are just too many of them (especially since I moved to non-plastic alternatives). So I began to wonder if I could find other gardeners who could use them instead: allotment holders, perhaps, or community gardeners, CSA volunteers and the organisers of school gardening clubs.
I started with an ad on Freecycle, there are other swap communities too where you can advertise unwanted but useful stuff, like Freegle and Preloved(though this last is mainly for buying & selling second-hand, it accepts ads for free stuff too.)
It was the second or third time I’ve tried this, and the results this time were much the same. A little flurry of responses: three, on this occasion. Followed by… well, basically nothing, as nobody turned up when they said they were going to.
Perhaps it’s just where I live. Or perhaps community gardeners are far too busy to do things like logging on to Freegle in the hope that someone will be advertising pots today. Anyway: as a strategy for tackling the teetering piles of plastic pots in my garden this is hit-and-miss at best.
So, I thought, perhaps I should take my pots to needy gardeners rather than waiting for them to find me. The first people I thought of were community, school and therapy gardens. Only trouble is, it’s hard to know where to start in getting in touch with them to find out whether they could use the contents of my shed without the time-consuming fuss of ringing round each and every one.
Enter…. the Free Pot Swap Shop!
Actually it’s not a swap at all really (I just liked the name and Noel Edmonds was an indelible part of my childhood). It’s just a place for anyone who wants to get their hands on other people’s pots to let other gardeners know about it.
As soon as I’ve collected a few responses I will start a page on this website with a list by county of any organisation or individual who is willing to take donations of used pots, trays, modules or any other gardening equipment.
After that it’s up to gardeners with donations to contact the organisation to arrange a drop-off.
If you are interested in receiving donations, please fill in the form below. Alternatively you can get in touch with me on Twitter (@sallynex or using the hashtag #gardeningwithoutplastic).
If you are interested in passing on your pots I will post a link here and more prominently on the website as soon as the page is up.
Please clean donated pots first and make sure they are in good working order. Thank you!
I got quite excited when I heard that there were people making a business out of going round collecting surplus plastic pots from garden centres.
What a great match. Manufacturer seeking recycled plastic to make stuff seeks garden centre with customers looking to get rid of plastic mountain: everyone’s a winner.
Except…. as it turns out, it’s not that easy.
There are two main companies who have tried this, as far as I can see: and both have come unstuck.
Ashortwalkis a Cornish company (the name comes from the fact that it is “a short walk” from the sea), founded in 2003 by ex Dyson designer Daniel Dicker. It is the company behind recycled plastic Ecopots and also makes recycled plastic plant labels, plant holders, bird feeders, sundials, house numbers. Recycling depends on people actually buying the recycled products too, so i would urge you to take a look at what’s on offer – a lot of it is really very funky stuff.
It didn’t take Dan long to realise there was a massive unused resource sitting about in garden sheds which he could tap into. We all see our garden pots as a nuisance; Dan sees them as raw material.
“Old plastic plant pots are not collected,” he says. “They have no value. They are light, but shipping is expensive; they are just not viable for recycling. But, if you create a product that uses them… well now it is financially viable to recycle this product.”
So he set up another company, Pot to Product, to collect this resource. The idea is that garden centres sign up, customers offload their plastic pot surplus to the garden centre, and Pot to Product comes along to pick them all up and take them to Cornwall and turn them into more pots, bird tables, plant labels and sundials.
Sounds great, doesn’t it?
Unfortunately, global economics has put its great clumsy boot in it and kicked it all to smithereens. I spoke to Chris at Ashortwalk, who told me the value of recycled plastic is at an all-time low, just at the time when the cost of diesel to transport it from garden centres to Cornwall has risen to an all-time high. It is, quite simply, more expensive to collect it than the recycled plastic is worth.
He said China’s recent decision to stop taking in the world’s rubbish has played a part too: labour costs in China are low, so they can afford to sort the many different kinds of plastic you get in garden pots and trays. UK labour costs are (relatively) high: sending the price of collecting, sorting and recycling garden plastic up even further.
Officially, the scheme is ‘suspended’: but it will take some fairly major economic upheaval to change the maths.
The other company that has dabbled with the idea of collecting plastic pots for recycling is Axion Recycling, a Manchester-based company which specialises in turning the steady stream of waste we pour out of our homes and lives into new stuff. Mainly, they recycle cars; but in 2011 they trialled collecting and recycling plastic plant pots. The scheme was along the same lines as Pot to Product: they teamed up with garden centres across the North of England and went round collecting surplus plant pots to take back to the recycling depot. It seems to have been short-lived: I can find no reference to it beyond 2011, and I haven’t (yet) been able to find anyone in Axion who can let me know how it went. I suspect it may have fallen foul of the same problem: the economics simply don’t stack up.
And that’s it. National schemes are just too difficult to be a practical solution. So the only option for our poor garden centres is to go to the trouble of setting up their own bespoke deal with a nearby plastics recycling centre (if they are fortunate enough to have such a thing) to collect customer’s pots. It’s not impossible, and some have – the garden centre in the previous post, for example.
But it’s hardly core business for garden centres, and it’s a problem not of their making in any case. So it seems unfair to demand that they.pour resources into recycling: better, surely, to put those resources into pressuring their wholesalers to use recycled (at least) or biodegradable (ideally) pots instead.
Back to the drawing board, then. Next solution: passing it on…
There are about 500 million plastic plant pots in circulation at any one time. Which? Gardening did a survey a few years ago and worked out that the average gardener has at least 39 (they clearly didn’t visit my shed: I’ve never exactly counted them but I must have hundreds in there).
Back in the dark ages, when I started gardening, almost every garden centre had a big box outside where you could drop off all your surplus plant pots, bedding trays and modules and if you wanted to, pick up a few you were short of to use at home.
Reusing your plastic pots, seed trays and modules is better than recycling them (because you don’t use the extra energy required to recycle old plastic into new). You make the most of a finite resource by using it until it falls apart, thus keeping it out of the wider environment and the oceans too for as long as possible.
It’s still not the whole answer: even if you do reuse plastic until it’s begging for mercy, it will eventually crack, split or get squashed by an errant wheelbarrow. So it will, inevitably, end up in the plastic waste food chain in the long run, which generally means landfill or albatross stomachs. Which is why (at the risk of repeating myself) it’s better not to have the plastic in your garden in the first place.
Still, when you can’t use all the plastic you already have, it’s good to have somewhere you can share your surplus. The only trouble is, these days almost all garden centres have stopped doing this and the big boxes full of random pots and trays have largely disappeared.
However all the larger garden centre chains, as far as I can see, have stopped. The largest of them all, the Garden Centre Group (including Wyevales) stopped their pot recycling service in 2011. Dobbies and Notcutts were doing a ‘bring back your pots’ scheme till 2012; but these days Notcutts undertakes to recycle 75% of its waste without specifying what, and Dobbies has a stupendously vague ‘sustainability policy’ on its website which makes no mention of plastic at all.
For the Garden Centre Group, it was all about the difficulties in finding someone to take the surplus away. They recognised that the scheme was popular with customers but couldn’t find anyone to undertake the huge task of sorting the many types of plastic used to make pots before recycling them. These days, there are several options (I’ll be going into these more in part 3 of this series) – so I will ask the GCG whether they are reconsidering.
Another major group, Squires, is ‘holding discussions with suppliers’ over alternatives to plastic. That could mean anything, of course. I remember my local Squires in West Horsley, Surrey having a big box of pots outside the front, into which I would regularly skip dive for whatever I needed; I asked them why they took it away and they told me they became inundated with plastic pots nobody wanted, whereupon they were lumbered with the task of getting rid of it. You can sympathise; garden centres, after all, are meant to be selling us plants (well, mostly), not processing waste.
People do complain loudly and bitterly about the disappearance of pot recycling bins at garden centres. But the more I think about the whole idea of taking your plastic to the local garden centre, the more I think it’s not such a good thing after all. It’s easy, of course. But aren’t you just passing on the problem? There’s no guarantee that all the pots you take to the garden centre will be picked up by someone else and reused, of course.
And what happens to the ones nobody wants? Some garden centres do take great care and some considerable trouble over finding a company they know will recycle their customers’ pots: Cleeve Nursery, stand up and take a bow. Others join a service like ashortwalk which collects and repurposes rigid plastic for recycling – so again, you know it’s going to be properly recycled (this and other national pot recycling schemes will appear in more detail in the next bit of this series).
But can you really guarantee you know for sure your garden centre is recycling the pots which are left behind? I suspect this might be the reason why a lot of garden centres have now stopped collecting pots: because they are, on the whole, well run and principled places which care about the environment and don’t want to have to throw away all those pots either.
You may argue that it’s garden centres which create a lot of the plastic waste in the first place. But it isn’t, actually. It’s the suppliers who supply the garden centres: the wholesale nurseries and growers and international mass plant producers who send huge shipments of plants around the country, all in plastic pots and trays, to fill garden centre shelves. And the garden centres themselves don’t have a great deal of say in that, as there are precious few wholesalers (actually only one that I’ve found) who do supply in biodegradable pots, so if garden centres supplied only those plants they’d have very thinly stocked shelves.
The real irony is that plastics recyclers – the people who turn your plant pots into plastic garden furniture and the like – find it hard to get hold of enough rigid plastic for the products they need to make. So it’s not like there’s no demand for the things. It strikes me that the whole system needs sorting out and joining up somehow. It’s just that I don’t think garden centres are the ones who should be doing it.