A much greater variety of ingredients is being used in bagged compost, or growing media, than ever before. This can present challenges around usage and make it difficult for gardeners to ensure they’ve made an environmentally friendly choice.

Added to this is the fact many brands of compost do not specify the exact ingredients, with packaging littered with descriptions such as ‘sustainable’, ‘natural’ and ‘biological’ - which are largely meaningless in terms of making an informed purchasing decision.

The Responsible Sourcing Scheme for Growing Media can help navigate this minefield. It was created as a direct outcome of the Government’s 2011 peat alternatives task force. Representatives from all sides of the debate had a part in its creation and many of these people, including myself, remain on the steering group.

Everyone from the big retailers such as B&Q and Homebase, to NGOs such as the RSPB, the RHS, Defra, growers and growing media manufacturers have played a part. The wide diversity of input has ensured acceptance of the scheme across the breadth of the horticultural industry and the conservation movement.

Know the score

So how does the Responsible Sourcing Scheme help gardeners make better choices when buying bagged compost? The scheme requires manufacturers to count the impacts of their ingredients across seven criteria – energy, water, habitat and biodiversity, renewability, resource use efficiency, pollution and social compliance. There are closely drawn rules for each criterion so that everything relevant is captured, with defined starting and end points.

These impacts are counted and distilled down to a final product score calculated from the amount of each ingredient in the mix. Scores range from A to E, the highest being A, indicating the least impact across the seven criteria. Consumers can look out for the Responsible Sourcing logo on the bags of participating manufacturers and obtain a score either by following the on-pack QR code or by looking up the product on the Responsible Sourcing Scheme website.

The final score is a distillation of a huge amount of data. For example, for energy, all of the energy consumed in the making of each individual ingredient, together with the transportation between processing sites, is counted. At Melcourt, where I’m senior associate and technical lead, most of our ingredients originate in UK forests so we’re required to count the energy consumed from tree planting, through felling, debarking, composting and screening together with all of the lorry transport between sites. It’s a lengthy and complicated task.

Another useful example is that of coir. It’s commonly thought that bringing coir (a by-product of the coconut industry, and globally a widely used peat alternative) all the way from India or Sri Lanka must be costly in terms of carbon emissions. By counting the energy for every stage in its processing and transportation, however, we can see more clearly how this material compares with British-produced ingredients. And it’s not as stark a difference as is sometimes supposed.

There are several reasons for this. The coir is washed with naturally collected rainfall and dried using sunshine as a natural energy source. Next comes compression into blocks, which provides very efficient use of transportation and high out-turn volumes once the coir is reconstituted at UK growing media manufacturers’ sites. And transportation to the UK is by sea, which is one of the most efficient forms of freight haulage in terms of the energy required per unit of weight and distance.

This is a good example of how we are now using data and evidence to demonstrate impacts rather than relying on the supposition and misinformation that has sometimes dogged this controversial subject. Added confidence for the consumer comes from the fact that the scheme is fully externally audited.

Other factors that contribute to responsible sourcing

The energy required to manufacture and transport a product can plainly have an environmental impact, but the scheme also recognises that factors such as water use and habitat loss are important. Renewability is relatively easy to score with peat and minerals such as loam, perlite and vermiculite at the bottom end of the scale and green compost, bracken and wool at the top.

The importance of social compliance is being acknowledged in similar schemes across many industries and this one is no exception. The Responsible Sourcing Scheme recognises we cannot label a compost as responsible if the employment conditions at any of its manufacturing stages are not compliant with modern day standards.

Manufacturers are also required to carry out a prescribed growing trial alongside the scoring system, as we also need products to function effectively as well as being responsibly sourced.

Who’s part of the scheme?

Most UK growing media manufacturers are members, although not all have scored all of their products yet. The scheme is also open to retailers and growers, and more of these are signing up each month. In future, it will become harder to gain the same scores as requirement for continual improvement will be built in.

It’s highly likely the new government will resurrect the intention to ban the use of peat, although no timescales have been given at the time of writing. But as more alternatives to peat come into use, it will be more important than ever that ingredients are scrutinised, so they not only work as effective growing media, but are also as benign as possible in terms of their environmental and social impacts.

Why swap to peat free?

Up to 95% of UK peat bogs are degraded or gone, due to drainage for agriculture, forestry and peat extraction, with huge amounts sold as bagged compost. It can take a whole year to create just 1mm of peat: that’s 1,000 years before the bog can start functioning again as a rare and special habitat, and carbon store.

The previous Government had planned to ban peat in retail bagged compost by the end of 2024, and for professional growers by 2026 (with limited exceptions). The new government has yet to publish any dates, but they are known to be sympathetic to the banning of peat use in the UK. In August, the Peat Free Partnership, of which Garden Organic is a member, sent an open letter to the UK Government to legislate to end peat sales.

But you can go peat free now! Here are our top tips:

Make your own compost mixes. As with any consumable, bagged growing media are packed in plastic and moved around in lorries, so it remains important to make as much homemade compost as you can. You can also experiment with your own recipes. For sowing seeds, mix one-part garden soil (loam) with one-part well-rotted leafmould and sieve out any lumps. You can find more compost recipes here.
Don’t skimp on how much you spend. Unfortunately, cheap peat-free compost, often made from green waste, can give you poor results. Invest in your garden and growing by buying the best you can afford.
Check your potted plants. Clearer labelling on peat-containing products is desperately needed. Peat can be found in many pre-potted plants , leafy salads, and houseplants. Mushrooms are also one of the few vegetables that are currently grown in peat so any packs you buy at the supermarket will have a peat footprint. Always check what you’re buying and make sure your garden centre or supplier knows you’d like to buy peat-free products.
Water little and often. Because of their coir and woodchip content, some peat-free mixes can dry out more easily. If they have a coarse texture, it can mean they appear dry on the surface but may still be damp further down. Check by putting your finger around 1 inch into in the soil. Don’t let them dry out otherwise they can be difficult to water again, as the water runs off the top. If this happens, sit the pot in water to let it draw up the moisture.
Feed after four weeks. Most peat-free composts provide fertiliser up to four weeks, but after this you can make your own comfrey liquid feed for hungry crops and container-grown plants. Find out how to make this at gardenorganic.org.uk/comfrey.

Catherine Dawson is senior associate and technical lead at Melcourt Industries Ltd, one of the UK’s leading manufacturers of sustainable, peat-free growing media. She’s worked with bark and horticultural growing media for well over three decades, following a degree in Soil Science. As previous Chair of the Growing Media Association, Catherine has been very actively involved in the cross-industry sustainable growing media task force and Responsible Sourcing of Growing Media Scheme.

For more advice on using peat-free compost and its benefits, plus a free online peat-free growing course click here.