What is the Growing Media Initiative? 

The Growing Media Initiative (GMI) is a scheme developed by the Horticultural Trades Association in conjunction with the Growing Media Association, DIY and Garden Centre retailers, Defra, the RSPB and the Royal Horticultural Society.

Positive progress continues to be made towards the development of a new Responsible Sourcing scheme to replace the existing GMI scheme. A pilot scheme launched in 2016, and is ongoing.  

History of the Growing Media Initiative

It was developed in 2008 order to help the horticultural industry in the UK meet government targets for reduction in peat use.  Peatlands are an important habitat and carbon store globally and it is now widely recognised that it is important to minimise further drainage of peat bogs and peat extraction.  The GMI scheme aims to increase consumer awareness about the need to protect the world’s peatlands and the need therefore to use more sustainable materials for growing their plants and improving the soil in their gardens. It also aims to provide a mechanism to encourage growing media manufacturers to develop and market effective peat replacements

The UK Biodiversity Action Plan (1997) stated that the horticultural industry should aim for a minimum of 40% of total market requirements (soil improver plus growing media products) to be peat-free by 2005 and 90% by 2010.  The 2005 target was met due to the combined efforts of suppliers, growers and retailers in the horticulture sector.  n the Environment white paper passed before parliament in June 2011 ambitious targets were embedded with regard to the cessation of peat use in growing media. These challenged industry to phase out peat use in three stages: use by governing bodies by 2015, in the amateur market by 2020 and lastly by the commercial sector by 2013. In order to achieve these targets the then Government through Defra instigated the formation of a ‘Task Force’(TF) to identify across the supply chain how the targets might be achieved or where barriers to such aspirations might preclude the desired outcomes.

Defra appointed Dr Alan Knight, a well-known environmental stewardship campaigner as the first chairman of the group and a wide range of individuals from; manufacturers of GM, Composters of waste streams, Commercial growers, Trade bodies (HTA&NFU), Major retailers and NGO’s (FOE & RSPB) were included in the formation of the first Task Force.

Very quickly Alan Knight helped the group to bring together a review of the issues, identifying a number of project streams which might be necessary to achieve the evidence and deliver changes in practice to meet the targets. The Task Force aligned the projects with specific time bound objectives that formed the basis of the “Roadmap”.  This document was sent to Defra for a response and as a result this initial ‘Roadmap’ was agreed.

One of the Projects identified, called P4, has made significant progress. It has  engaged across all sectors of the supply chain and from the outset looked to establish criteria which could be used to assess all of the main bulky materials used in GM. (Note: It was also decided at the outset that anything included at less than 5% by volume would be out of scope.)


P4 - Responsible Sourcing and Manufacturing of Growing Media - An Introduction and Overview

 The group working on this project arrived at the following criteria to be factored into consideration as to the way in which materials are sourced for growing media products. It identified seven criteria:

1.       Energy use (in extraction, transport and production)

2.       Water use (in extraction, processing and manufacturing)

3.       Social compliance

4.       Habitat and biodiversity (impact of gaining the materials)

5.       Pollution (effluents as a result of production processes, not fuel use)

6.       Renewability (feedstock material)

7.       Resource use efficiency (source of material and waste generated in processing).

 For each of the criteria a decision tree has been drawn up, allowing the user to arrive at a score for the specific criteria. To support the user there is a comprehensive set of guidelines and to allow easy accumulation of the information, an Excel spreadsheet has been produced which leads to a summary sheet of the score of specific materials or mixes thereof.  The information is now ready for industry use and testing ahead of future modifications. It is anticipated that this will be used as part of an upgraded accreditation scheme for manufacturers and as an evidence-based criteria for Growers and Retailers to use to determine how best to improve responsible sourcing of growing media.

All of the above has been achieved by serious collaboration throughout the supply chain and on a voluntary basis. The bringing together of all parties to work on these various exercises is really shaping the future of many aspects of UK horticulture for the future.


Responsible sourcing calculator and guidance notes are now available
To view the latest version of the calculator and associated documents please click here.


Latest News 

  • A number of Committees and sub-Committees are now established and working on individual work streams to develop the scheme, including Audit, Membership, Benchmarking and Technical requirements.  Full details of these including the lead contacts and the remits of each group can be found below in the document titled "Groups". 
  • Peat and Coir Workshops were held in November and were well attended. The discussions enabled a number of recommendations for refining the Coir and Peat Habitat and Biodiversity Trees and these will be reviewed by the Technical Committee on the 21st January. A report on the output from the workshops is available below.   
  • The Benchmarking committee will also be meeting in January to discuss and recommend suitable benchmarking levels for each of the trees. This will be guided by the feedback given by manufacturers who have started to carry out provisional assessments of their diluents. There will be an opportunity to comment on the proposed levels before they are set.  
  • The audit requirements that will underpin the scheme are also under development and the sub-committee are examining what documentary evidence will be needed. Members are also working up a costings proposal for the audit scheme to be drawn up and the auditor costs to carry out the audit.