How far can we go in designing alternative growing media mixes that will protect these habitats?
The destruction of our global rainforests has long been high on the climate agenda. The felling of trees at scale is a known contributor to climate change and the biodiversity crisis. These vast carbon stores have long been threatened, as has the wildlife that calls the canopies home. But also threatened are the ‘rainforests’ much closer to home. The UK’s peatlands face a significant threat, and peatlands across the country are as globally vital a carbon sink as the rainforests of the Amazon. Our national peat stores hold thousands of years’ worth of carbon; they lock the warming gas deep in the ground. However, the practice of removing peat from these areas for use in growing media releases this stored carbon back into the atmosphere.
Peat is the dominant substrate used by the UK horticulture industry and amateur gardeners to grow plants in containers, although the proportion of peat used in growing media has reduced in recent years, to 41% in 2020, and it is blended with other components, predominately wood-based material, coir and composted green waste. Peat is used because of its ability to hold water and provide air porosity. When it was first used, it was markedly lighter than the soil-based media commonly in use, and it enabled growing media to be standardised, with greater control of pH and nutrient levels.
Using peat as a growing medium, however, has contributed to the degradation of peatland habitats. The peat that is extracted from bogs for use in growing media is formed of partially decayed organic matter that has begun to break down in wet, acidic environments. The lack of oxygen in these waterlogged environments prevents the plant material from fully decaying. These peatlands in turn support unique assemblages of vegetation and associated species and have often developed over millennia. They are significant carbon stores and can also help in the regulation of flooding. Excavating peatlands across the UK is not only damaging the habitats that are vital for a diverse range of species, but it also releases stored carbon back into the atmosphere.
On 18 December 2021, the government launched a consultation calling for views on proposals to phase out the sale of peat and peat-containing products for amateur growing by the end of this parliament. The consultation also proposes introducing point-of-sale measures such as a charge for peat products and making it mandatory to report on the volumes sold. Additionally, the consultation is collecting evidence on the aim to end peat use in the professional sector by 2028. These measures aim to prevent peat extraction for the purposes of the horticulture industry.
With a ban on peat use in growing media on the horizon, can we effectively replace peat with alternative materials, and in doing so, protect peatlands? What does this mean for the horticulture industry and are these alternatives viable to enable the phasing out of peat for this purpose? ADAS projects, funded by Defra, the Agriculture and Horticulture Development Board (AHDB) and the industry, have provided valuable insights into how we can design, evaluate and increase the use of non-peat growing media.
Join us on Thursday, 13 January 2022 for a #GreenDialogues webinar to understand the progress made in providing alternatives to peat in the horticulture sector. Experts from ADAS, an RSK group company, will discuss the role and value of our national peatlands and will explore what we can do to restore it.
Further information about growing media for horticulture can be found on our growing media service page.