Responsible Sourcing Criteria

The Responsible Sourcing Scheme (RSS) for growing media is an industry-led initiative (developed by the Growing Media Association in collaboration with DEFRA and NGOs) to measure the sustainability of growing media and its ingredients. Each major raw material (making up >5% of a product) is assessed against seven key criteria covering environmental and social impacts. These seven criteria are Energy Use, Water Use, Social Compliance, Habitat & Biodiversity, Pollution, Renewability, and Resource Use Efficiency. By scoring each component on these factors, the scheme provides an overall sustainability rating (graded A to E, with A being the best) for the final product. Each criterion carries equal weight, up to 20 points each (for a total of 140 points per material), and the RSS encourages continuous improvement so that manufacturers can improve their scores over time.

Energy Use

Energy Use looks at the energy required to extract, process, and transport each raw material. Materials produced with renewable or low-carbon energy (like solar or wind power) score higher than those relying on fossil fuels like coal. In practice, this means a substrate made using energy-efficient machinery or 100% renewable electricity will earn a better score than one using conventional grid power.

Improvement: Manufacturers can boost their energy score by switching to cleaner energy sources and improving efficiency, for example, installing solar panels, using fuel-efficient vehicles, or streamlining transport routes to cut fuel use. Such steps not only lower the carbon footprint but also directly translate into a higher responsible sourcing rating.

Water Use

Water Use measures how much fresh water is consumed in sourcing or manufacturing a material. The less water used (especially potable water), the better the score, since water is a finite resource that must be used carefully. This criterion covers water for irrigation, washing, or processing during raw material production, while excluding naturally available water like rainwater that is harvested and reused.

Improvement: To improve on water use, companies can adopt water-efficient methods (e.g. drip irrigation or closed-loop rinsing systems) and maximise the use of non-potable sources like captured rainwater or recycled greywater. Regularly monitoring water consumption, fixing leaks promptly, and setting reduction targets are practical steps to use water more efficiently and earn a higher Water Use score.

Social Compliance

Social Compliance is all about people and ethical sourcing. This criterion ensures that the workers involved in producing the raw material are treated fairly and work under safe, acceptable conditions. It checks for adherence to labour standards; no child or forced labour, fair wages, reasonable working hours, and proper health & safety measures throughout the supply chain. A material sourced from suppliers with robust social audits or certifications (like Sedex, BSCI, or SA8000) will score well here.

Improvement: To improve Social Compliance scores, companies should expand audits and oversight of their suppliers, especially high-risk or high-volume ones. Encouraging smaller suppliers to join recognised ethical standards or complete approved self-assessments also helps. Ongoing training, regular reassessment (every year or two), and prompt correction of any issues ensure continuous improvement in labour practices and thus a stronger social responsibility rating.

Habitat & Biodiversity

Habitat & Biodiversity evaluates the impact of raw material sourcing on ecosystems and wildlife. The goal is to minimise habitat destruction and even enhance biodiversity where the material is produced. For example, peat sourced from a non-protected bog with a rehabilitation plan in place (to restore the wetland after extraction) will score higher than peat taken from a pristine, high-conservation-value peatland with no restoration. Likewise, wood fibre from sustainably managed forests (that avoid deforestation and support regrowth) would rate better than wood from unchecked logging.

Improvement: Companies can raise their Habitat & Biodiversity performance by sourcing from responsibly managed sites and implementing restoration or conservation plans. This might include prioritising raw materials from already degraded areas rather than converting new wild lands, ensuring any extraction comes with a funded plan to rehabilitate the habitat, and shifting to alternative materials (e.g. using agricultural by-products or renewable fibres instead of peat) to reduce pressure on sensitive ecosystems. Such efforts help protect biodiversity and improve the score in this category.

Pollution

Pollution considers the local environmental pollution caused by producing or processing materials, things like air emissions (dust, fumes), water runoff, soil contamination, and chemical spills. It checks whether manufacturers have identified their pollution risks and put controls in place (filters for dust, containment for effluents, proper waste handling) and whether they comply with environmental permits. The lower the pollution and the better the controls, the higher the score.

Improvement: To improve on Pollution, manufacturers can implement stricter pollution controls and best practices. For example, installing dust filters, odour control systems, and wastewater treatment can significantly cut emissions and discharges. Training staff in proper chemical handling and spill response is another key step. Regularly monitoring air and water quality around the facility helps catch issues early. Going beyond the legal minimum requirements, proactively using cleaner technology and swiftly addressing any incidents will lead to a better pollution score under the scheme.

Renewability

Renewability gauges how quickly the resource can regenerate or be replenished. If a raw material renews rapidly within a human timeframe (for instance, wood from fast-growing trees, coconut coir, which is a by-product of annual crops, or compost from organic waste), it scores well, whereas a material that is non-renewable or takes centuries to replace (like peat or certain minerals) scores low. In fact, recycled materials are treated as fully renewable in this context, since they are reusing existing resources rather than extracting new ones.

Improvement: While the inherent renewability of a given material is fixed, companies can improve their overall Renewability score by choosing more renewable inputs. This could mean replacing slow-renewing ingredients like peat or rock with fast-renewing or recycled alternatives. Increasing the proportion of recycled or sustainably harvested materials in the mix directly boosts renewability points. For example, sourcing wood from well-managed plantations that regrow quickly or incorporating innovative materials (like farmed sphagnum moss as a peat substitute) can make the product mix more renewable over time. By actively favouring materials that nature can replace quickly, manufacturers enhance their sustainability profile in this category.

Resource Use Efficiency

Resource Use Efficiency measures how well each material’s production process utilises resources and how much waste is generated. In simple terms, it asks: for a given amount of raw material, how much ends up in the final product versus being discarded? If a process generates a lot of off-cuts, scrap, or unusable by-products that go to landfill, it will score poorly; conversely, processes that use materials fully and create minimal waste score highly. Using by-products or waste from other industries as an input (for example, reusing sawdust from timber mills or composting green waste) also improves efficiency, as it means less virgin material is needed.

Improvement: Manufacturers can improve Resource Efficiency by reducing waste at each step and finding beneficial uses for by-products. For instance, optimising cutting or milling processes can leave less scrap, and any remaining waste can be reused or recycled instead of being landfilled. Many growing media producers already take this approach – e.g. reprocessing oversized compost pieces or using all parts of a harvested plant. Another strategy is to partner with suppliers who have high efficiency practices, such as sawmills that utilise every part of the log (lumber, bark, sawdust). Tracking the input-output balance and investing in better technology over time helps set targets and continuously improve this score, moving towards a zero-waste ideal.