ReGrow4C: Reuse Growing media for Circular cultivation

Project Details


Main research question/goal

The ReGrow4C project investigated whether peat substrates could be reused. At the ornamental plant cultivation company Pieters Jozef & Luc, investments were made in upgrading and reusing decomposed peat and perlite substrates, originating from strawberry and cucumber growers in the area. Together with the Experimental Centre for Ornamental Horticulture (PCS) and Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), this company has thoroughly reviewed this storage and processing process and, where necessary, adjusted, optimized and made it more sustainable. Based on the conviction that these materials can be reprocessed into a high-quality growing medium, this process was also examined in light of the legal framework.

Research approach

After being used in one crop, we reuse these materials as raw material for another crop. We further fine-tuned this application by optimizing the processing process through steam treatment. The efficiency of the hygienization process was tested for plant pathogenic fungi, vine weevil and weed seeds. The quality of the processed growing medium was assessed for both physicochemical and biological properties, and fertilization and composition were adjusted. The sanitized substrates were thus upgraded to a final product employable for various crops, and were tested within ReGrow4C for some ornamental crops.


The ReGrow4C project investigated the possibilities for upgrading and reusing decomposed peat and perlite substrates originating from strawberry and cucumber growers in the area. We showed that the heating process (steaming at 100°C and 1 hour storage at 70°C) is efficient for killing off the tested plant harmful organisms and weed seeds. Moreover, steaming has only a limited effect on the physicochemical properties. The steamed substrate degrades slowly, and is as stable as new substrate. The recycled (steamed) substrate has a relatively high pH and already contains a lot of nutrients. The latter indicates that the fertilization of the next crop should be adjusted accordingly. The above ground plant parts contain a lot of nutrients relative to the cultivation substrate and have a high degradability. It is important to remove the above-ground plant remains first or to allow them to decompose for a sufficiently long time in a stored pile under sufficiently moist conditions. 

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