GETTING RID OF PLASTIC POTS

- The search for a truly biodegradable alternative.

It started with a single plastic pot. When Malcolm Woolmore, director of Auckland’s Lyndale Nurseries and keen sailor, found a single-use plastic plant pot washed up on an otherwise pristine beach near Great Barrier Island, he was horrified. “I thought to myself, ‘That’s not very impressive’, and I wanted to do something in my little way to help get rid of plastic.”

That lone discarded plastic pot set Malcolm, and Lyndale, on a long and winding road to find alternatives to single-use plastic pots for their seedlings.

Plastic waste – in packaging and labels as well as pots

– is a perennial thorn in the side of modern gardeners who, as a rule, are trying to celebrate the natural environment and do right by it.

And as Lyndale Nurseries, among others, have discovered, it is not a simple problem to solve.

Each stage of the gardening sector from propagation nurseries such as Lyndale to large retail chains such as Kings Plant Barn, have different requirements from the products they use to houseplants, particularly in terms of sturdiness and lifespan.

Unfortunately, there are currently few alternatives to those handy single-use plastic pots that meet all those varied requirements and can be produced at scale for a reasonable cost to meet demand.

While the Ministry of Environment and industry body New Zealand Plant Producers (NZPPI) work to find solutions to the problem of garden plastic waste, for the moment the job is falling largely to individual nurseries and businesses – and gardeners.

For Malcolm, that has meant trialling biodegradable options at Lyndale.

The first attempt, made about 15 years ago, involved using a pine-resin plastic with existing injection moulding techniques.

When that didn’t work, Lyndale turned to a Chinese company that could make pots out of the same process but this time using ground up bamboo and rice husks with a secret ingredient to bind it together. It worked to a point, allowing roots to eventually break down the pot walls. Then the pot, complete with plant, was placed inside a larger pot at the point of sale. So far so good – except that customers rebelled, thinking retailers were trying to sell them a small plant at a larger plant price.

“And if anything went wrong with that plant, because it was something different, it always got blamed on the pot,” Malcolm says.

But the problems weren’t just with perception. “The primary issue was that secret ingredient that we had no control over. We just didn’t know, from batch to batch, how long they were going to take to break down, even though we specified we wanted them breaking down in eight to nine months. We had a lot that broke down too quickly, and were falling apart in the nursery. We have other samples here that still haven’t broken down.”

So the company went back to the drawing board. After trialling a couple of other products and more searching, Lyndale is now in its second year of trialling Grownets, made in the Netherlands from a 100 per cent biodegradable polymer – again a secret formula – that resembles a hair net. “It seems to be working beautifully. We are getting that eight to nine months and then they appear to be totally gone. The soil organisms appear to eat them,” Malcolm says.

Lyndale is now in its second year trialling Grownets, made in the Netherlands from 100 per cent biodegradable polymer that resembles a hair net.

“But it is only a percentage of our production that is suited to it. It depends on the type of root system.”

While Lyndale is finding some success for at least part of their business in reducing plastic waste, it seems that other parts of the garden and nursery sector haven’t been as successful.

Not all biodegradables are equal

As Rachel Barker, CEO for industry body Plastics NZ, says, while there are some interesting and genuinely compostable developments in plastics, there is also a high risk of greenwashing with many products marketed to consumers as biodegradable, when they actually require extremely specific conditions – not all of which are easily replicated in the home garden – to break down.

“Our recommendation here is to ask for evidence as to the length of time it takes for these materials to break down, and what conditions are required to achieve this,” she says. “If they differ from ‘real world’ conditions, be very careful. It will likely take a lot longer to break down than expected.”

Plastics NZ would like to see more systems in place to make the reuse and recycling of single-use plastic pots easier for consumers.

Many of these plastic pots are made from Number 5 polypropylene plastic, which is in high demand in New Zealand as a recycled plastic. Ironically though, this type of plastic is not accepted in most council kerbside recycling bins.

“We would like to see all plastic plant pots made from this material, reused as much as possible, and then sent for recycling once they’re at the end of their life,” Rachel adds. “What we really need is a product stewardship scheme which pulls all the relevant businesses together to form a nationwide collection, reuse and recycling system.”

That system would need to deal with cleaning huge volumes of pots to remove things such as highly abrasive pumice often used in potting mix and not compatible with recycling processes.

And, at the propagation end of the nursery chain, reusing plant pots at scale is complicated by the need to clean and sterilise each pot to avoid the spread of pests and disease.

“We used to be able to fumigate pots with metal bromides but that, quite rightly, has been banned,” says Malcolm. “So now there’s no effective way of sterilising them, because we are talking about millions of pots.”

Reuse/recycle

But cleaning and reusing pots on a domestic scale is more straightforward. Garden retailer Kings Plant Barn now has reuse/recycle swap-a-pot stations in all stores as part of its goal to reduce plastic waste. Customers can drop off used pots for other customers to pick up for repotting or seed sowing.

Pots that are not reused are collected and sent to Kiwi company Future Post, which recycles the plastic into fence posts.

But Kings general manager Chris Hall says most pots left in the stations are taken by other customers to be reused. “It’s very popular, and at the moment for us, recycling and reusing is a more viable path than trying to find a biodegradable option that works,” Chris says, adding that customers increasingly expect garden centres and nurseries to be actively implementing more and more sustainable practices.

“We’re looking at everything we do from our packaging and mailers to our wrapping material, and working with our waste company to reduce what’s going into landfill.”

Every little bit helps, according to Manawatū gardener Kath Irvine who has been trying to find ways to reduce plastic waste in her garden and business, the Edible Backyard, “as long as I’ve been gardening really”.

“It’s a bit ironic really. Creating these beautiful, organic gardens off the back of all that plastic,” she says.

She too is sceptical about the efficacy of current biodegradable pots for home gardeners and believes encouraging people away from a single-use mentality is better.

“I’m not sure the biodegradable ones are much better than plastic. Can you actually home compost them? There is a bit of greenwashing in there, once you start to look into it. But I appreciate that people are just trying different things in a difficult situation.”

Kath, who works with other gardeners to help them create thriving edible gardens and is shortly releasing a book on the topic The Edible Backyard, falls firmly into the reuse camp. “Imagine how many plastic pots and six-cell containers that are already floating around in the world that could be recycled and reused.”

In her own garden, Kath’s approach is to minimise the number of products she uses and the amount of plastic packaging she accumulates. “It’s hard to eliminate plastic completely, so start out with the goal of reusing it and just reducing it where you can. If you can’t cut out pots, look at other ways you can reduce other plastics.”

She also buys plants from Manawatū’s Awapuni Nurseries, famed among its loyal customers for avoiding plastic pots and wrapping seedlings in newspaper.

Awapuni owner Henri Ham says the business goes

Top: Manawatū gardener Kath Irvine of Edible Backyard. “It’s a bit ironic really. Creating these beautiful organic gardens off the back of all that plastic,” she says. Above: Kings Plant Barn’s pot recycling station.

through about 15 tonnes of newspaper every year, wrapping “the majority of plants that leave the property”. Most are grown in plastic trays, which are washed, sterilised and used “over and over again”, then transferred to the newspaper for sale.

Henri says the seedlings can last in the paper for about a week before it will start to get soggy. Plant stands at the point of sale have capillary matting to prevent the newspaper drying out the soil.

But Awapuni doesn’t use newspaper for everything. Natives and perennials are in traditional plastic PB bags.

“We’ve been looking for options to replace those, but it’s been really difficult,” Henri says. “We need something that holds together while [the plant] is growing and also holds together through being transported and retailed.

So it needs a reasonably long lifespan but, if it’s biodegradable, you also don’t want it to last too much longer after that.”

At this point, finding biodegradable solutions that don’t cost a fortune, or require huge infrastructure investment to be made in large numbers, yet will remain viable for a fairly specific amount of time, seems a lot to ask.

The way forward

NZPPI chief executive Matthew Dolan says it’s not simply a matter of finding a plastic alternative. “There are many options for alternatives to plastics for plant pots. And

“We need something that holds together while the plant is growing and also holds together through being transported and retailed,” says Henri Ham.

there are people really busy innovating and finding clever ways to use them.

“The challenge is scaling them. To scale anything, you need a massive amount of capital. You need the right material and you need to integrate it into the supply chain to test it. It’s a lot of work and it’s really expensive.”

But there is good news. Matthew says large amounts of plastic have been removed from the supply chain as the use of paper pots in the early stage of propagation is expanding.

There is also opportunity to create a circular economy and reuse plastics in a much more efficient way. “At the moment it is ad hoc. It is individuals setting up recycling bins and trying to get that plastic back to a place that can clean and reprocess it. The industry needs to come together to find the most efficient way to do that.”

Matthew says the tipping point will likely come with government intervention. “Plastic plant pots have been given priority product status, which means there will be regulation around them in the future. It may mandate that there is a recycling system in the future. Then it will be up to the industry to decide how it will respond to that legislation.”

In the meantime, NZPPI is focused on trying to pull the industry together to replicate some of the primary sector recycling systems already in place.

“Primary industry has recycling processes for all sorts of waste such as silage plastic and containers from farms. They have coordinated recycling system at scale that are well-resourced.”

The organisation is also working with growers in Australia to understand how it is tackling the same problem over there.

“Our industry really does understand the need.

It is front of mind and there is a lot of commitment to actually making progress,” Matthew says. “But we do need the public on board as well. We need them to commit to putting their pots back in the system.”