Plastic substitutes, Plastic-free gardening

The alternatives #1: Bamboo and cardboard

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).

Bamboo

bamboopots_greentones.co.uk
Bamboo pots from http://www.greentones.co.uk

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

western-pulp-tomato-gravel
Tomatoes growing in cellulose pots by http://www.westernpulp.com

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.

Stockists:

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 Organic do 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.

Other products:

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.

Next: Clay and coconut fibre (coir)

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Plastic substitutes

If not plastic, then…. what?

So far I’ve been concentrating on what to do with the plastic you’ve already got.

But once you’ve taken the pledge not to buy any new plastic for your garden (and done your best to fend off the plastic that keeps trying to get back in) you still need pots, and seed trays, and hanging basket liners. So if not plastic, then what?

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)
  • miscanthus
  • spruce wood
  • bamboo
  • rice husks
  • straw
  • cow manure
  • starch
  • cellulose
  • cardboard
  • terracotta clay

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.