Hydroponic tomatoes perform best when their roots can breathe and are not submerged in excess salts. Coco provides that hard-to-find balance: a light bed with usable water that does not drown the roots and a reserve that remains stable throughout the day. However, not all coco is the same; its origin and processing determine residual levels of potassium, sodium, and chlorides. Therefore, starting with washed and “preloaded” coco or acquiring it already conditioned allows the plant—not the substrate—to set the pace during the initial growth stage (Gbollie et al., 2021; Konduru et al., 1999).
Efficient Irrigation: Combining Light and Vapor Pressure Deficit (VPD)
Irrigation schedules are largely defined by sunlight but are adjusted according to VPD and, increasingly, sensors that provide direct readings of substrate water status or moisture percentage. Scheduling irrigation based on radiation sets the window for turning the water flow on and off. However, climatic factors such as relative humidity and wind affect transpiration and, therefore, root water uptake. One approach is to let light open the irrigation window and VPD control the dosing within it, adjusting size and pauses according to the drainage obtained. Cloudy or windy days require subtle changes to maintain optimal moisture without compromising the plant (Lizarraga et al., 2003; Shin et al., 2014).
Drainage: The Safety Valve in Soilless Cultivation
In soilless systems, drainage is critical: water entering with salts must exit with salts, preventing salinization of the root zone. Many growers monitor water, pH, and electrical conductivity (EC) by sector. This practice is not bureaucratic but a control tool that ensures rhizosphere EC stability, fruit size, plant health, and even organoleptic quality. If EC rises, corrections must be gradual: reduce concentration, increase the drainage fraction during critical hours, and return smoothly to the optimal range, or severe consequences may occur (Wei et al., 2018).
Coco Texture and Its Impact on Roots
Coco particle size determines oxygen and water availability. Fine fractions retain more water and reduce macropores, slowing root response; coarse fractions improve aeration but store less readily available water. Irrigation management must adapt: airy mixes require more frequent sips, fine mixes longer pauses. Batch or granulometry changes require three days of observation to adjust the strategy without shocks (Gbollie et al., 2021).
Indoor Climate and Ventilation: Complementary Factors to Irrigation
Early ventilation dries the canopy, reduces disease pressure, and facilitates calcium transport to the fruit. Screens and window management smooth VPD peaks, protecting both the substrate and the plant. The combination of light, VPD, drainage, and clean substrate ensures that adjustments translate into yield, firmness, and consistent production without complex routines.
References
- Gbollie, S. N.; Mwonga, S. M.; Kibe, A. M. (2021). Effects of Calcium Nitrate Levels and Soaking Durations on Cocopeat Nutrient Content.
- Lizarraga, A.; Boesveld, H.; Huibers, F.; Robles, C. (2003). Evaluating irrigation scheduling of hydroponic tomato in Navarra, Spain.
- Wei, X.R.; Cheng, R.F.; Yang, Q.C.; Yongkang, H.E.; Zhang, C. (2018). Research of the irrigation mode controlled by cumulative radiation on tomato growth and water and fertilizer utilization in greenhouse.
- Shin, J.H.; Park, J.S.; Son, J.E. (2014). Estimating the actual transpiration rate with compensated levels of accumulated radiation for the efficient irrigation of soilless cultures of paprika plants.
- Pires, R.C.M.; Furlani, P.R.; Ribeiro, R.V.; Bodine Jr., D.; Sakai, E.; Lourenção, A.L.; Torre Neto, A. (2011). Irrigation frequency and substrate volume effects in the growth and yield of tomato plants under greenhouse conditions.
