Research outputs

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Main research question/goal

ReGrow4C aims to substantially extend the life span of peat-based growing media. Chrysanthemum growers Pieters Jozef & Luc have invested more than 2 years in upcycling and reuse of spent peat and perlite based growing media from nearby strawberry and cucumber growers. Together with the Extension Research Center for Ornamentals (PCS) and Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), the chrysanthemum growers optimise and increase the sustainability of storing and processing spent growing media. As these processed materials can be converted into high-quality growing media, the process will be benchmarked versus the legal framework for improving the market introduction.

Research approach

After using growing media for one cultivation, we aim at reusing the spent material as substrate for another crop. The reuse of growing media based on steam treatment will be optimized. The efficiency of the steam treatment will be tested with plant pathogenic fungi, vine weevils and weed seeds added before processing. The quality of the processed growing medium is assessed based on both the physico-chemical and biological characteristics, and if needed, the blend is optimized and fertilizers added. The steam-treated growing media is then upcycled to an end product applicable for a range of crops, and tested for use with ornamentals within ReGrow4C.


The extraction of peat from pristine peatlands is highly controversial because these activities are seen as threatening sensitive ecosystems and carbon sinks, resulting in increased emissions of greenhouse gasses. Each batch of peat that is reused results in a clear reduction in CO2 emissions and a lower impact on the climate. Direct reuse of spent peat and perlite based growing media is a new application within the research on the valorisation of residual materials at ILVO. ReGrow4C will result in local reuse of growing media and a local market for the upcycled material. The project results in a higher availability and composition of mixes for propagation and growing media for growers of ornamentals, vegetables and soft fruits.

External partner(s)
PCS - Proefcentrum voor de Sierteelt
Effective start/end date1/12/1731/10/19

ID: 5901478