pro landscaper magazine
pro landscaper magazine

Professional horticulture might be exempt for now, but a ban on using peat is looking ever more likely by 2030. The government announced last August that sales of peat to amateur gardeners in England will be banned from 2024, and it pledged to help the professional horticulture sector speed up its transition to peat-free alternatives, recognising that it faces “additional technical barriers that will take longer to overcome.”

There are growers, though, which are already taking the leap. Take Greenwood Plants, which says it is on track to be fully peat free by the end of this year. One in four plants are already potted in peat-free compost, which managing director Melanie Asker says the nursery plans to ramp up as it enters the growing season. “As growers of around six million plants a year, this is a huge undertaking, but we are fully embracing the peat-free challenge.”

As is Kent-based How Green Nursery, which managing director Simon Sutcliffe says is “well on [its] way to achieving peat-free status.” Whilst the majority of its home-grown and bought-in plants continue to be grown in peat, it is currently ‘growing on’ in peat-free alternatives. It has been trialling these for the last 15 years before settling on its “current recipe” 18 months ago.

“We are now really happy with the quality of the plants and losses are minimal,” says Sutcliffe. “Importantly, water consumption has not increased from the days of using peat. Our growing media contains mainly bark fibre which has the ability to retain water during the summer months.

“A lot of peat-free compost is based around coir fibre that isn’t great at holding water – water being a valuable and sometimes scarce commodity with extremes of weather. Coir is also shipped halfway around the world, so the carbon footprint is not good.”

And carbon is, after all, one of the biggest reasons the industry is looking to address its use of peat. Peatlands are the UK’s largest carbon store and extraction releases carbon dioxide into the atmosphere, contributing to climate change. Not only that but it also disturbs habitats in the wider landscape and reduces the peatland’s ability to mitigate flooding. As such, the government’s goal is to restore 35,000ha of peatlands by 2025, with only 13% in a near-natural state at the moment.

Following government proposals back in 2011 to address the degradation of peat bogs, Nicholsons – a landscape company in Oxfordshire which has its own 22-acre nursery – started incrementally trialling peat-free alternatives on all its crops. Last year, it accomplished growing all its production potting in peat-free compost.

One of the challenges in switching has been around managing water and nutrition. There have also been some “rooting ‘issues’” and a “difference in crops”, which plants director Merlin Brooke-Little says “have not always been to the crop’s detriment but have been different to the peat standard.”

By slowly switching over to peat and monitoring the process, Nicholsons has developed a better understanding of how different crops require various levels of water and nutrition, but Brooke-Little says that managing the compost and the feed in extremely hot weather is still a “learning process”. “Finding the sweet spot of enough water at regular intervals over leeching nutrient does require constant attention.

“The compost mix will have been adjusted several times over the years to account for wetting agent, base fertiliser and amount of CRF (controlled release fertiliser) per m3. We have had concerns over the heating of the compost when held in bulk bags and when tipped loose – sometimes the heat would be such that the CRF would have been activated. Regular turning and cooling of the compost have helped.”

To tackle rooting being poor and more noticeable in the top five to 10cm of its pots, where the crop tends to dry out the most, Nicholsons now puts bark mulch on its crops to help maintain a better equilibrium in that layer.

It’s a series of trial and error for these nurseries, and Bernhards Nurseries is arguably ahead of the curve. The nursery, situated in Rugby, switched to producing all its plants peat free 10 years ago, having felt the need to change from its customer base. It swapped peat for Melcourt Silvamax, which managing director John Marsden had years of experience with and felt would be best suited for the wide range of plants and trees grown at Bernhards.

“Working with Melcourt, we selected the right mix, CRF content and any additives to suit, and got to work,” explains Marsden. “The first few years we had some small issues, but it was simply a learning curve. [Scottish minister] Neil Gray was a great support, really helping us to tweak our production to suit. The overall technical backup was a great help, and over the past decade the professional Silvamix media has continued to improve, to the excellent blend we have today.”

Bernhards’ water usage has reduced, perhaps surprisingly, as a result. It waters more frequently but for shorter periods, reducing its water usage by on average 7% each year. “The media feels ‘more open’ due to having a higher ‘air-filled porosity’ (AFP) than peat,” says Marsden. “We have also noticed that we get fewer losses from water logging, reducing wastage due to this. In some cases where we know we will be potting hungrier plants that may be in the pot longer – such as some evergreen shrubs – we may ask for a slightly higher amount of CRF to be added to the blend.”

The biggest problem for nurseries at the moment, though, is finding suitable peat-free compost for seedlings, explains Sutcliffe. “We and other growers are finding this the ultimate challenge as heavy losses are being incurred at the moment. Once we nail this issue, our status will be totally peat-free.”

Then there’s also the “hesitance of other growers both here and especially abroad to make the switch,” he adds. “We outsource plants for our clients, and all but one supplier is still growing in peat.”

For Asker, the challenge Greenwood Plants expects to face as a commercial grower is getting a reliable and consistent supply of peat-free growing media that is economically viable. “Our trials involve exploring new types of growing media to support our annual production – we are trying different commercially available peat-free growing media. The trials allow our production team to tweak the growing media composition to get the pH, nutrient levels and structure right, as well as alter the irrigation programmes to compensate for the lack of moisture-retaining peat” – all of which seems fruitless if the suitable alternative is not available in vast quantities.

This is potentially where the RHS’ new £1m five-year to research sustainable alternatives to peat in large-scale commercial settings comes in. It has appointed peat-free postdoctoral fellow Dr Raghavendra Prasad to help the horticultural trade transition to sustainable growing media by working with five growers which collectively produce more than 46 million plants each year.

Professor Alistair Griffiths, director of science and collections at the RHS, says: “It’s vital that the RHS works collaboratively with industry and government to research new, peat-free growing media technologies. We know there are already many peat alternatives out there, and even more as yet untapped, so we need to collaborate to develop and share best practice guidance to ensure that peat – which when intact can store carbon for thousands of years – stays in the ground.” And ensure the government’s target of restoring 35,000ha of peatlands by 2025 seems more within our reach.

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