From laboratory trials to public engagement: how PEATLESS is advancing alternatives to peat

Peat remains a key component of many growing media because it combines water and nutrient retention, low weight and physical stability. Those same characteristics make it difficult to replace. At the same time, peat extraction affects ecosystems that are important for biodiversity and carbon storage, while future availability may be constrained by stronger protection of European peatlands. The PEATLESS project addresses this challenge by evaluating alternatives to peat in horticulture, using renewable materials and by-products as potential components of lower-peat and peat-free growing media.

Recent work by project partners shows that this transition depends on more than identifying a promising raw material. Candidate blends must perform under cultivation conditions, fit within existing regulatory frameworks and be understood by the people who may eventually use them. Activities led by CTICH, CREA, AVI and CITA illustrate these complementary dimensions of the project.

CTICH refines alternative casing soils for mushroom cultivation

At the Mushroom Technological Research Centre (CTICH), PEATLESS is testing alternatives to peat for use as casing soil in the cultivation of Agaricus bisporus. CTICH is currently carrying out its second laboratory-scale trial, building on an initial experiment that compared 12 alternative blends with a conventional casing soil made entirely from peat.

The first trial followed the formulations throughout the cultivation cycle. Researchers assessed water retention, irrigation needs, mycelial development, fruiting and production. This made it possible to identify the strengths and limitations of each formulation rather than judging performance through a single property.

The second trial focuses on the blends that performed most promisingly and introduces reformulated options based on the knowledge gained. The raw materials under evaluation come from renewable resources or by-products generated by other sectors. They include spent mushroom substrate, plant fibres, composted bark, vermicompost and sheep wool. Their use could reduce dependence on peat while giving a new purpose to materials with limited applications.

Replacing peat is not a matter of finding one identical material. It requires blends whose physical and chemical properties work together under real cultivation conditions.

Find more about CTICH: https://peatless.eu/alternative-materials-mushroom-casing-soil/, https://peatless.eu/low-peat-casing-soil-mushroom-cultivation-la-rioja/

Performance depends on how materials are combined

Each candidate ingredient behaves differently. Some materials retain large amounts of water, others provide greater aeration, and differences in structure can affect how quickly mycelium colonises the casing soil. This is why every formulation must be tested experimentally before commercial use can be considered.

The work has also revealed practical constraints. Sheep wool, for example, is subject to specific requirements for agricultural use. Other environmentally promising materials need adjustments to achieve physical properties closer to those of peat. Small quantities of auxiliary materials may therefore be added to improve structure, water retention or aeration.

Chemical parameters are equally important. A pH close to neutral or slightly alkaline supports crop development, whereas excessive electrical conductivity can restrict mycelial growth and negatively affect production. CTICH characterises each formulation and makes the necessary adjustments before cultivation trials begin.

The next stage will continue this iterative process. Once the laboratory trials have been completed, the five best-performing formulations will be selected for semi-commercial testing in CTICH cultivation rooms. This phase will examine whether results remain stable and reproducible under conditions closer to commercial practice.

Italy is encouraging reduction without a general peat ban

Technical progress also takes place within a wider policy and market context. In Italy, peat remains widely used in floriculture, nursery production, horticulture, vegetable transplant production and soilless systems. Italy also depends entirely on imported peat, adding an economic dimension to the environmental debate.

According to the overview prepared by the Italian Council for Agricultural Research and Economics (CREA), there is currently no general ban on peat use in growing media for these sectors. Legislative Decree No. 75/2010 and Regulation (EU) 2019/1009 allow peat as a raw material while requiring appropriate labelling and compliance with contaminant and agronomic requirements. The present framework therefore focuses primarily on product safety and commercial transparency.

Nevertheless, European and Italian policy measures are encouraging a gradual reduction. The European Green Deal and the EU Biodiversity Strategy for 2030 support lower-impact alternatives. In Italy, Regional Rural Development Programmes and Green Public Procurement also favour sustainable practices and, through Minimum Environmental Criteria, growing media with reduced peat content.

Find more about CREA: https://peatless.eu/peat-regulation-italy/

AVI prepares ornamental plant trials in the Pistoia district

The transition has particular importance for Italy’s ornamental potted plant industry. These crops are grown in customised substrates that must provide adequate water availability and drainage, retain nutrients and remain free from pathogens that could damage root systems. Peat has fulfilled these technical requirements for decades, which explains both its continued importance and the difficulty of replacing it without affecting plant quality.

The contribution prepared by the Italian Nursery Growers Association (AVI), which is implementing PEATLESS in collaboration with CIC, places this work within the scale of the sector. It estimates the Italian ornamental potted plant market at approximately EUR 1.68 billion, with around 70% of production exported and more than 15,000 companies involved in cultivation.

Tuscany accounts for approximately 30% of national ornamental plant production, and Pistoia is Italy’s main production area for ornamental potted plants. Its specialised supply chain brings together growers of different sizes, substrate producers, agronomists, technical specialists and service providers. According to the AVI source article, the district includes more than 1,500 companies and generates approximately EUR 500 million in annual revenue. This concentration makes Pistoia a strategically important location for testing alternatives under commercial conditions.

AVI’s overview also describes a structural supply challenge. Peat demand is increasing in international horticultural markets while peatland degradation, greenhouse gas emissions and climate pressures are strengthening the case for reducing extraction. For growers, this creates a need to balance reliable supply and price stability with environmental responsibility and the consistent quality required for professional production.

Within PEATLESS, AVI and CIC will work with local growers to conduct experimental trials on ornamental plants in the Pistoia area. The trials will evaluate locally sourced alternatives designed to reduce peat use. The Italian approach specifically excludes coconut-based materials and includes compost, aligning substrate development with resources and production conditions in the territory. Beyond technical performance, the work also aims to address the social and economic barriers that can slow the adoption of new growing media.

CREA has supported this transition through research initiatives including BIOVIVO, EDEN, SUPERA and HT-HG. This body of work reflects a clear direction: alternatives such as quality compost, composted bark, wood fibres, lignocellulosic materials and suitably processed organic by-products are being investigated, even though matching peat’s properties remains technically demanding. In this context, PEATLESS can contribute evidence for more sustainable and resilient production systems.

Find more about CREA: https://peatless.eu/peat-regulation-italy/

CITA brings substrate research into the classroom

Public understanding is another part of the transition. On 28 April 2026, the Agrifood Research and Technology Centre of Aragon (CITA) presented PEATLESS during the eighth international Fascination of Plants Day. The event brought together 68 participants, including students and teachers from Movera High School and Rio Gallego High School, as well as CITA laboratory technicians and predoctoral researchers.

CITA researchers introduced the environmental reasons for reducing peat use and the need to identify locally available alternatives. Students and teachers then examined selected raw materials and prepared blends, using sight and touch to identify their components. Materials present in smaller proportions were easier to distinguish, while the main components looked more similar to peat. This visual similarity may help the acceptance of alternative substrates, although cultivation performance remains the decisive test.

The session also translated technical parameters into simple demonstrations. Participants compared water retention by adding the same volume of water to equal amounts of different materials and measuring drainage. They observed aeration through the bubbles produced when water was added and compared pH using test strips. The activities showed why a substrate is much more than ‘simply soil’: it must provide the physical, chemical and microbiological conditions required for plant development.

Find more about CREA: https://peatless.eu/peat-regulation-italy/

A transition built on evidence

Taken together, these activities show the practical scope of the PEATLESS challenge. Laboratory, ornamental plant and semi-commercial trials are needed to determine which formulations work in different horticultural contexts. Regulation and procurement influence how quickly lower-peat products can enter the market. Outreach helps future professionals and the wider public understand why substrate properties matter.

The results available so far are promising, but the project has not yet reached a final formulation that can simply replace peat in every context. Its value lies in the step-by-step development of objective criteria: identifying suitable materials, understanding their limitations, adjusting their properties and validating their performance under increasingly realistic conditions. That evidence-led process is what can turn peat reduction from an environmental objective into a technically credible option for growers.