Supporting the phase-out of peat in hobby gardens

Peatlands are among the Earth’s most effective natural carbon sinks. When they are drained, large quantities of CO₂ are released into the atmosphere. Peat is used, amongst other things, in potting compost. In Germany, amateur gardeners use around 4.5 million cubic metres of this each year. Although the proportion of peat in potting compost has fallen from 55 to 33 per cent since 2019, this falls well short of the target set out in the federal government’s peat reduction strategy of completely phasing out peat in the consumer sector by 2026.

Challenges in using peat-free substrates

Why is it so difficult to do without peat? From a horticultural perspective, peat is an ideal raw material for growing media. Its chemical properties can be precisely tailored to the needs of plants through the addition of fertiliser and lime. Furthermore, peat stores an enormous amount of water whilst simultaneously supplying the roots with sufficient oxygen.

At present, none of the common substitutes can fully replicate these positive properties. Consequently, peat-free potting soils differ significantly from traditional peat-based soils, particularly in terms of water-holding capacity, nutrient content and nutrient dynamics. This requires adjustments to watering and fertilisation practices. The most significant peat substitutes currently in use include green waste compost (36 per cent), wood fibres (17 per cent), bark humus (6 per cent) and coconut-based products (2 per cent).

The predecessor projects to HOT2 – HOT1-TV2 and HOT1-TV3 – made it clear that many amateur gardeners underestimate these differences and use peat-free substrates incorrectly. Care and fertilisation routines were therefore tested directly in practice in real-world laboratories. Participants documented watering, fertilisation and plant development. The results show that, with adapted and substrate-specific management – such as nitrogen-rich fertilisers and precise dosages per pot – peat-free gardening is excellent.

Research findings directly from practical application

HOT2 is investigating in more detail how amateur gardeners obtain information on using peat-free potting mixes and how they apply this information to their daily plant care. At the same time, practical tips and resources for using peat-free potting soils are being demonstrated through display and demonstration plantings. These plantings provide a learning space designed to further raise public awareness of the issue.

Another key focus of the project is purchasing behaviour. In collaboration with retail outlets and specialist garden centres, the project is investigating how consumers can be encouraged to buy peat-free potting soils and how the necessary information can be communicated to them. At the same time, HOT2 is addressing the issue of professional development: in collaboration with pilot schools, teaching programmes on peat-free gardening are being developed.

“The aim is to present the findings in such a way that they can be put to immediate practical use and accelerate the switch to peat-free potting soils,” emphasises sub-project leader Dr Dieter Lohr.

Information for editorial teams

HOT2 is funded by the Federal Ministry of Agriculture, Food and Rural Affairs from January 2026 to the end of September 2027. The Agency for Renewable Resources (FNR) is the project sponsor. Project partners are the Nürtingen-Geislingen University of Applied Sciences for Economics and the Environment and the Erfurt University of Applied Sciences.

Further information on HOT2 is available on the HOT2-TV3 and HOT2-TV4 websites, as well as in this HSWT research magazine article, which contains links to a wide range of information and training materials.

We would be happy to arrange an interview with the HSWT project leaders, Dr Dieter Lohr and Prof. Dr Klaus Menrad.

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