Future directions of the global growing media industry: insights from Dutch Policy up to 2050

1 Introduction

Climate change is regarded as a global threat affecting nature, including humanity (Shukla et al., 2022; IPCC, 2018). The emission of carbon dioxide is regarded as a main driver of climate change and a factor that should be reduced. The reduction includes fossil carbon from coal, oil, gas, calcareous rock (as an input for concrete), and peat (Verhagen et al., 2009; IPCC, 2006).

Measures to reduce peat in horticultural applications have been taken in, among others, Switzerland, the United Kingdom, Germany, and Ireland (Waller, 2006; Litterick et al., 2025; Hirschler et al., 2022). Despite various points of view (Carlile and Waller, 2013; Schmilewski, 2014), this resulted in an increasing volume of research on renewable raw materials for growing media (Hirschler et al., 2022; Gruda, 2012, Gruda, 2020; Barrett et al., 2016; Vandecasteele et al., 2018). In this transition toward more renewable resources for growing media, the industry prefers a focus on life cycle assessment (LCA)-based comparisons rather than on peat reduction as such, to avoid stumbling from one problem into the next (MCS, 2023; GME, 2023). These tools fit in with the obligatory European Product Environmental Footprint Category Rules (PEFCR) framework (Helmes et al., 2020).

The main peat-related emissions in Europe are caused by mismanagement of agricultural peatlands (IPCC, 2006). Nevertheless, the use of peat in horticultural growing media contributes to emissions and needs to be reduced or changed into a circular product use (Vandecasteele et al., 2024; Van Tuyll et al., 2022). Another argument against peat use, i.e., the destruction of a natural habitat and its biodiversity, deserves nuance when the extraction of peat under certification is considered. Certification can be used by authorities to economically convert degraded or agricultural peatlands into areas with higher environmental value.

In 2021, the Turfvrij Action Group successfully motivated Dutch politicians to oblige the government to ensure a reduction in the use of peat for horticultural purposes (Boswijk and Bromet, 2021). In reaction, the Dutch Covenant “Agreement on environmental impact of potting soil and substrates” was signed by government officials and industry representatives (VPN, 2022a). Industry parties such as the united producers, VPN, and a certification body, the RHP (Regeling Handelspotgrond), paved the way by initiating certification for peat extraction (responsiblyproducedpeat.org) and by appointing a professional chair. Such actions also resulted in sufficiently reliable data to convince policy makers (VPN, 2022b). Lastly, the Covenant was signed not only by all individual VPN members and two ministries but also by parties along the whole production chain, such as Turfvrij, united composters, propagators and growers organizations, trade, and retail.

To further support and unify Covenant parties, a quantitative list of renewable raw materials with a horizon up to 2050 was commissioned to Wageningen University & Research (Blok et al., 2024a, Blok et al., 2024b). Once agreement over this list and its implications was reached, a second project was started to work data into an actionable plan supported and managed by Covenant partners. This was reported in the “Roadmap Renewable Raw Materials for Growing Media” (Boedijn et al., 2025).

The Dutch potting soil market serves approximately 8 Mm³ growing media annually including approximately 5 Mm³ of peat products (VPN, 2022b). The German market serves a roughly equal amount (IVG, 2024). Therefore, Dutch/German companies supply approximately 50% of the European market of 36 Mm³ annually (Hirschler et al., 2022). Europe produces roughly 60% of a total of 67 Mm³ growing media traded globally (Blok et al., 2021). The global market, however, is rapidly expanding, with vast amounts of novel companies from, among others, the USA, Canada, India, Sri Lanka, and China.

From a research point of view, a quantitative list of renewable raw materials and their availability and properties is the main goal. However, work on the Roadmap is also reported to clarify how basic data can be transformed into a program of balanced research (and communication) projects. A secondary goal of the availability report was to advice the Covenant on a percentage of renewable growing media in the professional market for 2030.

2 Materials and methods

2.1 Data acquisition and available raw materials

A total of 70 interviews lasting 1–2 h were held with leading persons in the total supply chain. From the confidential interviews, information on the quantities used in specific submarkets was combined into a national overview (reported in Blok et al., 2024a). Simultaneously, an extensive list of materials mentioned as possible growing media constituents was made, including their reported quantities, focusing on those available in Europe, but including the already common use of coir (Blok et al., 2024b). This list was based on a literature search and was expanded with information from the interviews. The report structure and emerging texts were discussed in four meetings with 30–45 representatives of Covenant partners. The final text was twice distributed to all partners for factual comments.

Criteria were set to bring this list down to a short list. The criteria included price, minimum quantities, competition from other industries, and various levels of risks. The price level was set to a maximum of €200/m³ growing medium, i.e., 5–10 times the current level. The price level was set to exclude too expensive materials, but was sufficiently high to avoid excluding materials that are not yet optimized for horticultural application. The minimum quantity was set to 100,000 m³ year⁻¹ as this quantity was believed to enable potting soil producers to invest in technology to process a raw material into a basic material for professional use. Competition with other industries was described qualitatively, based on the literature, to increase awareness of the present uses and related price levels, as well as awareness of future demands when growth of the biobased economy could increase competition for materials for building (especially concrete and asphalt), textiles, and circular plastics (Van Minnen et al., 2024). Care was taken to also describe emerging opportunities to use new residual flows from competing industries. Risks of a transition into new raw materials were touched upon, but not described in excruciating detail as the scope was to focus attention to the most promising material classes rather than to exclude every risk upfront. The general risks mentioned, however, need to be addressed to avoid damaging the global position of the potting soil industry.

2.2 From available raw materials to quantities of potting soil constituent

To arrive at reasonable estimates of the available raw material quantities for growing media, typically one or more conversions were required. Often, wet masses were reported, which had to be converted first into dry mass and then into a related volume. In the majority of cases, this initial volume needed further conversion from density as offered to density of a product fit for potting soils. For each material, there are references for the initial quantities and references for the factors used for each conversion step (Blok et al., 2024b). For some classes, the quantities are many times larger than the demands from the potting soil industry. However, these quantities are not freely available as they are spoken for by other users and must therefore first be made available in economic competition and in new commercial cooperation structures.

2.3 Grouping according to characteristics

The eventual short list was arranged into groups with shared characteristics. An analysis of the main drawbacks and the required technical amelioration of these materials was then made. The technologies described illustrate the required direction of the amelioration and present possibilities. However, up to 2050, additional technologies will become available.

2.4 Analyses of applications

The total market was split into a number of specific submarkets to set realistic development paths for each submarket and to ensure broad grower commitment. This made it possible to acknowledge that some submarkets can easily meet goals for renewable raw materials, but that some submarkets face specific rate-limiting restrictions. The development paths per submarket are based on interviews and on repeated debates in partner meetings.

2.5 Analyses of speed of adaptation

The increase in demand for raw materials needed for growing materials in the Netherlands was set to a modest annual growth of 0.55% until 2050, in contrast to the much steeper growth prognosis for the global market (Blok et al., 2021). Conversion rates for each submarket were used to first determine a realistic overall conversion percentage for 2030, and this figure was rounded off to arrive at a communicable figure for advice to the members of the Covenant.

2.6 Organizing for societal support

Covenant partners and Wageningen University took efforts to maximally involve stakeholders along the total production chain, including authorities and non-governmental organizations, when working on both the raw materials availability report and the Roadmap. The list of renewable raw materials and their availability was created from literature sources and further detailed by interviews with 70 stakeholders. The report was structured in four meetings with 30–45 representatives of Covenant partners. The final text was then twice distributed for factual comments (Blok et al., 2024a, Blok et al., 2024b).

To follow up on the report, a joint Roadmap for research steps up to 2050 was made (Boedijn et al., 2025). This Roadmap had to deliver an analysis of stakeholders of the production chain, including possible new stakeholders, growers, authorities, and society; an overview of the required research and development steps; an inspiring presentation, which is fit for communication to various non-specialist audiences; a structured list of actions with involved commercial and non-commercial partners per action; and a clear structure of the process management and responsibilities.

To realize this Roadmap, two sessions were held with approximately 40 representants of stakeholder parties (often branch organizations). The process was structured by a commercial company specialized in group communication. The results were graphically structured by a specialized university subsidiary. The final product was then twice sent to participants for factual comments.

3 Results

3.1 Types of raw material

The results showed 30–40 materials out of 130 that fit the criteria (Blok et al., 2024b). More than 99% by weight of this biomass is already allocated to competing users for building and for other purposes.

3.2 Quantities present and potential

The materials were then organized into a group with properties already accepted in the market (i.e., coir, coniferous wood fiber, coniferous bark, compost, and perlite) and a group of remaining materials (e.g., acrotelm, other types of wood and bark fiber, non-wood plant fiber, co-composts, and reused growing media).

3.3 Applications at present

The applications used per subdivision of the Dutch market are described and quantified for the present (Table 1). In some cases, submarkets are of relatively small importance when considering the total transition. The mention of smaller but specific markets is motivated by the wish to obtain support from as many growers as possible and the wish to address some specific transition problems of submarkets and their at times crucial interactions with the whole production chain.

Table 1. Market segments of the Dutch professional horticulture 2021 (VPN, 2022b).

The total production of growing media in the Netherlands is divided into export, consumer market, and professional market (as percentage of the total Dutch internal market and in m³*1,000). The professional market is further divided into ornamental and food, each of which is further divided into eight submarkets. In the last column, the use of renewable growing media is given (percentage of the total Dutch internal market).

3.4 Estimated adaptation rate

Market groups with higher adaptation rates were container orchids (using bark) and perennials. Market groups with adaptation rates lower than the average were mushroom casing and various propagation systems. There are quite diverse reasons for the lower adaptation rates, including the unresolved issue of suppression of budding of champignon mushrooms at levels of black peat below 50%, v/v (Noble et al., 2024; Taparia et al., 2021); difficulties in properly fertilizing propagation materials, including acid-loving plants on new mainly high-pH raw materials; nitrogen immobilization issues with too rapidly degrading new raw materials (Dickson et al., 2017; Beuth et al., 2022); and legal problems with the export of non-peat organic plugs.

The grand average finally advised was 50% (v/v) renewable materials in 2030 (Blok et al., 2024a).

4 Discussion

4.1 Technical value creation

The technical ameliorations required for market acceptance of the materials mentioned are challenging and need efforts from the industry, knowledge institutes, and the government (Table 2). Table 2 also shows that coir (pith), bark, compost, and perlite continue to play a significant role because, without their properties, almost no mixtures can be made without serious shortcomings. Other materials (and compost) need to be mixed with materials with complementary properties in order to be effectively used.

Table 2. Assessment of five established and six more or less upcoming renewable raw materials for six important properties.

There is still room for improved processing. Especially for WHC and WUR, processing might turn “−” into “+.” The term “semi-product” refers to raw materials mixed with other materials before processing, often by co-composting with established green compost feed materials. For each material, the score for typical high (Hi) and low (Lo) values is indicated with + and ++ for scores positive for cultivation and with − and − − for scores negative for cultivation. All negative scores are in the left part of the table, with all positive scores to the right. This means that “Hi” and “Lo” values are mixed as some properties are problematic with low values (e.g., stability), while others are problematic with high values (e.g., EC). The high and low values are based on experience in present-day cultivation, i.e., not based on a specific material such as peat. One “+” or “−” stands for “has this property,” while two “++” or “− −” stands for “has this property to a greater extent.” EC, electroconductivity; Stab., stability (as in biodegradability); pH, acidity/alkalinity; N-imm., nitrogen immobilization; WHC, water holding capacity; WUR, water uptake rate.

4.2 Consequences and risk management

The use of raw material produced in cultivation cycles of 1–50 years, such as grasses and trees, means that, compared with peat, which has aged for many centuries, there are specific risks that need to be managed, including risks of chemical and biological contaminants, risks of inhomogeneity and uneven supply over time, and risks of crop management for growers.

New raw materials often contain more residues of crop protection products, medicines and drugs, salts, heavy metals, plant diseases, and human diseases. Controlling such risks is essential for further acceptance of these new raw materials (Litterick et al., 2025). Therefore: a) certification and registration will become even more important and b) sanitation will become more important. Sanitation does not necessarily mean disinfection. Sanitation must, however, result in a quantified acceptable risk for growers and consumers.

Instead of supply from a small number of homogeneous sources, products from agriculture or nature management will come from a large number of highly variable sources. Therefore: a) certification and registration will become even more important; b) logistics, blending, and adding base fertilization will become much more complex; and c) long-term contracts must be offered to reduce fluctuations created by the wider transition to biobased production expected for building, textiles, and renewable plastics (Hirschler et al., 2022).

New raw materials generally are drier and higher in pH than the already accepted growing media. Combined with the need to adapt base fertilization, this obliges growers to adapt both their irrigation and their maintenance fertilization schemes. This may include adaptations in technology and requires a 3- to 5-year period of on-site experimentation to realize transition without undue risks for growers and customers. Grower acceptation, similarly to the risk level, is essential for the acceptance and pace of transition.

4.3 The Roadmap

In the Roadmap, focus is set on the combinations of more advanced processing, including particle formation; the use of less favorable actions for, e.g., sanitation; sanitization of materials; and stabilization of materials, specifying the base fertilization and the maintenance fertilization. Actions are taken by consortia of the supply industry and by organized growers, advisory companies, propagators, and retail companies. The goal is to address risks in every part of the production chain and to avoid creating new problems and problems for other parts of the production chain. A professional manager is appointed to guide the execution and related communication of the Roadmap actions by researchers and stakeholders.

The transition toward more renewable raw materials is expected to change the structure of the supply chain. New companies will enter the supply chain to produce, pre-treat, sanitize, and concentrate new raw materials; potting soil companies will develop new mixes with both other raw materials and additional substances such as various fertilizer qualities; and growers will adapt their methods of irrigating and fertilizing. Retail will also adapt plant care in transport and information to consumers. Many of these changes will require time to determine how to realize change while avoiding side effects such as increases in fungi, gnats, and fertigation problems for growers and consumers.

4.4 International relevance

The Dutch situation is not unique, and many European countries have taken similar relevant initiatives (Litterick et al., 2025; Hirschler and Osterburg, 2025). The Dutch example discussed here is thought relevant for Europe as the raw materials for potting soil and biomass in general already had to be sourced largely outside the small and densely populated Netherlands. Furthermore, the distances in Europe are relatively small, as witnessed by potting soils from the Netherlands being delivered as far as halfway Italy. The Dutch approach puts emphasis on communication and the involvement of the wider production chain. In terms of global developments, pressure to reduce the input of peat is still absent for growth markets such as China and South America. Nevertheless, these markets face delivery problems due to material scarcity (HortiDaily, 2025) and serious expansion of demands. Furthermore, the global increase in demand for biomass intensifies raw material competition. The international growing media industry is therefore also expanding or developing access to: coir (pith, chips, and fiber); bagasse (sugarcane residue); bamboo (only non-construction quality); and jute (Thiessen et al., 2023).

5 Conclusions

An analysis of the Dutch market until 2050 and the availability of reliable raw materials for this purpose in Europe led to the advice for a 50% (v/v) conversion from peat to renewable raw materials to be realized in 2030. Subsequent planning sessions with the production chain led to a research Roadmap with commitment from industry partners being responsible for initiatives and financing. The government accepted the Roadmap vision, which opens possibilities for government co-financing of specific research topics. Although this work is specific for Holland, the study on material availability in Europe and the research requirements to develop biomass materials are thought to be of global relevance. Sharing responsibility with commercial companies of the wider production chain is believed to be highly valuable as well, but undoubtedly requires adjustments to fit specific national circumstances.

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Footnotes

Edited by: Athanasios Koukounaras, Aristotle University of Thessaloniki, Greece

Reviewed by: Normunds Stivrins, University of Latvia, Latvia