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Half of gardeners unaware of what’s in their shop-bought compost, finds RHS

More than half of gardeners (57%) admit to not knowing what is in their shop-bought potting compost, a survey by the Royal Horticultural Society (RHS) has found.

With 30 million people thought to garden in the UK and sales of bagged potting compost soaring, the charity is urging gardeners to ensure they are buying peat-free products and making home compost to create their own soil improver.
 
More than half (53%) of the 2,000 gardeners surveyed reported buying five or more 50 litre bags of potting compost in the last year compared with just 8% of respondents buying in this quantity in 2013. These products were primarily used by respondents for filling pots and baskets (76%), seed sowing (75%) but also in improving garden soil (51%) where it is known to be less effective than specific shop-bought soil conditioning products and home-made compost.
 
However, issues of sustainability are now front of mind for many, with four in every five (82%) saying they were concerned about the environment compared with just three in ten (30%) in 2013. A third (37%) also said they already exclusively use peat-free bagged potting compost. For those that were not, cost (25%) and accessibility (25%) were the main barriers.
 
The recent IPCC report laid bare the risks to health, livelihoods and food and water security and included mitigating factors such as the preservation of carbon sinks such as peatlands.
 
Alistair Griffiths, Director of Science at the RHS said: “It is encouraging that nearly half of those surveyed are already peat-free but a large proportion of the tens of thousands of bagged potting composts bought each year may be going to waste in being used as a soil improver. By opting to make their own free garden compost or buying specific shop-bought soil conditioning products, gardeners can really help to speed up the transition to peat free.”
 
When home composting the RHS advises gardeners to:
  • Position a lidded bin – this can be any size - in light shade or shade. An earth base allows drainage and access to soil organisms, but if you have to compost on a hard surface, then add a spadeful of soil to the compost bin.
  • Aim for between 25 and 50 percent soft green materials (e.g. grass clippings, annual weeds, vegetable kitchen waste, or manure) to feed the micro-organisms. The remainder should be woody brown material (e.g. prunings, wood chippings, paper, cardboard, straw or dead leaves).
  • Ideally, place a lot of composting materials on the heap in one go, and turn it periodically – perhaps once a month - to introduce air. Failure to turn the heap is the main cause of poor results.
  • Mature compost will be dark brown, with a crumbly soil-like texture and a smell resembling damp woodland.
When opting to buy bagged potting compost it is advised that gardeners:
  • Look for a peat-free label. If the bag doesn't say peat-free then it most likely isn't.
  • Wording such as 'environmentally friendly', 'compost' and 'organic' can often confuse gardeners into thinking they are buying peat-free products, but they do not infer this.
  • A good quality peat-free growing media is usually a little more expensive. The price does tend to reflect quality.
  • Check the label on the bag to see if it is recommended for particular plant groups.
  • Read and follow any advice offered on the label of peat-free products as many need slightly different treatment to peat. Pay particular attention to watering and feeding requirements as these do tend to differ.  
The RHS stopped selling peat based potting compost in its plant centres in 2019 and has committed to being entirely peat-free across all of its activities by 2025.
 
The RHS website includes advice for gardeners on making their own peat-free mixes for plants and composting at home: https://www.rhs.org.uk/advice/plant-care/soil-care
 

Notes to editors

For more information please contact the RHS press office: pressoffice@rhs.org.uk

About the surveys:

In March 2021 the RHS surveyed 2,055 non-member gardeners about their use of potting compost.

In 2013 the RHS surveyed 1,000 gardeners about their use of potting compost. Of these just 7 were RHS members.
 

About the RHS:

The Royal Horticultural Society, the world’s leading gardening charity, was founded in 1804 by Sir Joseph Banks and John Wedgwood. Our vision is to enrich everyone’s life through plants, and make the UK a greener and more beautiful place. This aspiration underpins all that we do, from inspirational gardens and shows, through our scientific research, to our education and community programmes such as Campaign for School Gardening and Britain in Bloom. We produce key publications, hold a world-class collection of horticultural books and botanical art, and sell the very best plants and gardening gifts.

The RHS is fundraising £40m to transform our gardens, outreach and education facilities, which includes redeveloping our flagship RHS Garden Wisley and opening a new garden, RHS Garden Bridgewater, in 2021. We are solely funded by our members, visitors and supporters. For more information visit www.rhs.org.uk.

RHS Registered Charity No. 222879/SC038262

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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.