Workshop summary: practical management of peat-free growing media III

Key messages and presentations from the RHS peat-free workshop on 6 March 2024 at RHS Garden Harlow Carr

About the workshop

The third in a series of RHS peat-free workshops for growers took place on 6 March 2024 at RHS Garden Harlow Carr, Harrogate.

The workshop focus was practical management of peat-free growing media, with speakers including Dr Neil Bragg of Bulrush, Paul Hogben of Klasmann-Deilmann, and RHS Peat-free Transition Fellow Dr Raghavendra Prasad and Nikki Barker from the RHS peat-free team. 

Key messages and presentation slides from each of the speakers can be found below.

Paul Hogben – Klasmann-Deilmann

Peat-free growing media: a supplier’s perspective

Download Paul’s presentation (4.1MB pdf)

Key messages
  • Need to look at the long-term sustainability of all the ingredients in peat-free mixes, alongside any risks or advantages related to these materials 
  • ​A wide portfolio of raw materials that can be used in peat-free mixes allows flexibility in production and helps prevent shortages 
  • In addition to their individual properties, ingredients interact when mixed

 
  • Better accreditation standards for green compost is vital to build confidence in a product that is so widely available
  • ​Growing media manufacturers run thorough testing of all materials, which is key to maintaining quality  

Dr Neil Bragg, Bulrush

Paul Hogben, Klasmann-Deilmann

Dr Neil Bragg – Bulrush

Challenges in development and use of peat-free mixes for growers

Download Neil’s presentation (0.4MB pdf)

Key messages
  • Be aware of nitrogen lockup in peat-free mixes – you will probably need to adjust feeding times or frequency compared to peat-based media. Manufacturers can explain the nitrogen source in their mix and will give specifications on nutrient composition


  • Overwatering can lead to nutrient leaching, so watering regimes will also need adjusting with peat-free mixes
  • Trial any new mix you are considering, adjusting to get the best for their use

Nikki Barker – RHS

RHS peat-free policy for RHS suppliers and shows exhibitors

Download Nikki’s presentation (0.9MB pdf)

Key messages
  • The RHS is aiming to be 100% peat-free in all operations by 01/01/2026
  • The RHS peat-free policy for suppliers and exhibitors only applies to the plants that are used or sold at RHS shows or outlets; the supplier or exhibitor does not have to be 100% peat-free

 
  • Any potting action after 31/12/25 must use peat-free growing media. The products may still contain legacy peat (peat that was already in the production system up to 31/12/25)
  • We are here to help!

Nikki Barker, RHS

Dr Raghavendra Prasad, RHS

Dr Raghavendra Prasad – RHS

Monitoring crop performance

Download Raghavendra’s presentation (2.9MB pdf)
The RHS Transition to Peat-Free Fellowship is looking into key challenges across the industry by working with a range of industrial partners.

It is important to standardise peat-free trials against your regular growing media mixes as a control. Replicates help to ensure that human error or environmental factors are not giving a false result.

Trials are randomised and replicated. We do not give peat-free mixes any special treatment – we need to see how they perform commercially, and ensure any changes in inputs that could affect costs can be planned for.

Peat-free growing media needs to be treated differently – for example, with regards to irrigation and nutrition – as physical and chemical properties of the growing media varies depending on the bulk ingredients (woodfibre, composted bark, coir etc). 

Key messages
  • Trials in a commercial setting are being carried out across many plant groups at eight fellowship nursery partners as part of the RHS Transition to Peat-Free fellowship
  • Set out what you want to achieve before you start your trials
  • Ensure there is a control using your regular mix, and trials are repeated and randomised within your setting

 

  • Test the growing media at the beginning and the end of the trial, and also during trials if possible, to understand the trend/progression of physical and chemical attributes
  • Assess various parameters including selected morphological traits, economics of cultivation (inputs/cost implications) and most importantly plant saleability/marketability

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