In partnership with Grodan, the Caté experimental station in Saint Pol de Léon, at the heart of Brittany's vegetable and horticultural production zone, has set up a trial of soilless tomato cultivation, with the aim of comparing the behaviour of the plants and the environmental efficiency of the crop as a function of the nature of the substrate. "The Grodan Prestige stone wool slab was chosen for its versatility and competitive edge over coco substrates", explains Hans Baekelmans, Grodan's technical advisor for the Brittany and Northern Europe regions. Three types of substrate were compared in the trial: Grodan Prestige 10cm-high slab, buffered coco and unbuffered coco in the reference volumes commonly used in Brittany. The trial was set up in mid-December 2020 (pre-planting in week 50) with the truss tomato variety Luminance and an initial density of 2.33 plants/m². This density was then increased to 2.9 plants/m² from week 5, rising to 3.5 plants/m² from week 10. Harvesting began on 18 March, initially with trusses of 5 fruit. It continued from the beginning of May with trusses that had been pruned to 6 fruit.