For many years, environmental and economical constraints have forced growers to look for new substrates for replacing rockwool in greenhouse tomato production. Peat sawdust mixes have long been proposed as organic alternatives to rockwool, with however lower yields likely linked to irrigation and aeration problems. The development of high performing and easy to use matric potential sensors has provided an opportunity to refine this irrigation strategy. The objective of this study was to investigate the zone of hydric comfort of actively growing tomato plant to define appropriate irrigation setups and then to use these setups to grow tomato in comparison with rockwool. Defining new setups appropriate to 2 :1 (v/v) sawdust:peat substrate allowed total and marketable yield increases of 10.5 % and 10.3 % respectively in comparison with rockwool, without reducing tomato quality. Hence, an adapted irrigation strategy could allow growers to use a sustainable growing media, cheaper than rockwool while increasing their yield and economical performances.