The potting soil and substrate sector is navigating a period of significant change, driven by historic low peat availability and current scarcity of coir. This pressure is accelerating the market’s transition toward a greater share of renewable resources, as mandated by the Environmental Impact Agreement for Potting Soil and Substrates. The agreement is currently on track to achieve a 35% share of renewable raw materials in the professional market by the end of 2025.

According to the Dutch Association of Potting Soil and Substrate Manufacturers (VPN), this shift means more raw material mixtures will be used, and the substrate may look and function differently. Marco Zevenhoven, Operations Director at RHP, the European knowledge center for substrates, stresses that growers must be aware of these changing properties, as adjustments in cultivation, such as adding extra nitrogen during fertilization to counteract immobilization, may be necessary.

To manage quality during this transition, RHP is actively involved in facilitating innovation, including through its Innovation Support program. BiocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More and miscanthus are cited as examples of promising raw materials currently being explored under strict conditions that are not yet RHP-certified. These must prove sufficiently available and pass research before being eligible for certification, which currently covers 16 raw materials plus finished products.

Cultivation advisor Ruud den Dulk of Horti-Scan urges growers to intensify their entry controls. As mixtures become more complex, combining two or more products alongside peat, he encourages growers to request analysis results of the substrate from suppliers, or to sample their crops. RHP echoes this, noting that while sampling is part of the RHP quality mark, growers don’t request chemical and physical analyses often enough, which provide critical insights into a substrate’s EC, pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More, trace elements, and water absorption characteristics (WOK).

In a temporary measure to ease the peat shortage while maintaining quality, RHP has implemented a protocol for batch inspections of additional peat, which will be in effect until June 1, 2026. This permission for biochar could give it the opportunity it needs to break into the Dutch potting market, which is one of high quality and investment.

SOURCE: Advice to growers during substrate transition: Ask for analyses and act accordingly