Salad seedlings are grown in small blocks of sticky, nutrient-rich peat compost, then planted directly into the field.

We need to talk about peat

If we're successful in this project, we will share our findings - and help to eliminate the use of peat in the whole horticulture industry.

Moist, dense, chocolate-coloured peat. It may not look like much, but this soil is as precious as gold dust. Peat can take millennia to form, mainly from decomposed sphagnum moss. The rich variety of specialised plants which grow on peat, and the deep layers of waterlogged soil beneath, trap vast amounts of carbon; in fact, peatland is the one of the biggest carbon sinks on the planet. This makes peat-based compost a difficult subject for veg growers, including Riverford.

Many of you will be keen gardeners who manage to avoid peat, and may be surprised to hear that we still use it. We’ve worked hard to hugely reduce our use of peat, and have eliminated it altogether for most veg. But we haven’t yet found a successful alternative for growing salad crops. There’s just one sticking point – ‘sticking’ being the operative word.

Every year, we grow millions of salad seedlings in small blocks of compost, before using machinery to plant the blocks directly into the fields. For this machinery to work, the compost surrounding the seedling’s roots has to stick together as it’s transferred from the growing container to the ground. Not much holds together like peat, and not much provides the same nutrition for the seedlings.

In our Devon polytunnels, we’ve been trialling peat-free ‘modules’ for lettuces, onions, and tomatoes, planted by hand. Lettuce yields fell by 33 per cent, and onions by 50 per cent – but tomatoes showed real promise, with only a 15 per cent drop in yield. This winter, we’re going to trial planting lettuce and onion seedlings in biodegradable cellulose nets, which hold the loose, peat-free compost together like a plant pot. We hope this will improve our results.

The silver bullet, however, lies in the creation of a completely peat-free soil block, which sticks together for machine planting and provides good nutrition for seedlings. In partnership with Innovate UK, Delfland Nurseries, Cambridge Eco Ltd. and Coventry University, we’re working on a really exciting two-year project to develop this ideal block. Six months into the project, we’re optimistic that it will yield success.

This project is vitally important. If we’re successful, we will share our findings – and help to eliminate the use of peat not just in our own fields, but in the whole horticulture industry. Watch this space.


Leave a Reply

  1. Fantastic to hear about truly planet protecting research. One assumes this is highly marketable knowledge. Hoping for success! Oh and tasty salads as well.

  2. I so hope you are successful in this. We were trying to be peat free 30 yrs ago – and soon realised it was impossible – at the time. There were no manufactured peat free composts then – and even when they started to appear – they were useless – no water holding or root holding qualities. We got fed up with peoples rants about peat use when they had no idea how to make seedling/potting compost and they quite happily bought plants in plastic pots hand over fist!
    Our nurseries should go back to growing in the soil – and plants get bought when they are good and ready to be dug up.
    If you can find a seedling block medium that works then that is the silver bullet! Until then we should at least mess up our own peat not import it from other countries….
    The peat use for cooking/hesting is another problem – but since we saw fit to deforest places like Ireland….🌳🌱🤔

  3. This is great news! Here at BeadaMoss we have spent the last 15 yrs working to grow Sphagnum Moss for peatland restoration and as a peat alternative for growing plants. We have been working with RHS Wisley and 2 of the main media suppliers in the UK over the last 3 years with great success. Now scaling up production to meet market demand and would be great to talk.

  4. Sorry to be a killjoy, but disappointing really. As gardeners we have been well aware of the issues involved from the 1990’s onwards. We remember Geoff Hamilton banging on about it on Gardeners World and the Wildlife Trusts and Soil Association publicising their concerns even then. Over 30 years later, one would have imagined that such a forward thinking and dynamic company as Riverford would have been peat-free for years. Can’t help but feel that this topic has been deliberately kept off the radar. Great that this is happening now, but hard not to think that the motivation is perhaps the potential prospect of legislation.


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