Section 1: Water Management
Water is a major factor in the production of greenhouse crops, and greenhouses use large volumes of water for irrigation (estimated to be 0.5 gallons per square foot per day). Proper water management requires that the appropriate volume of water (or liquid fertilizer solution) be applied with each irrigation. This amount is typically a volume sufficient to thoroughly wet the substrate in the containers but not to result in significant leaching (water flowing out of the bottom of the container). Irrigation frequency depends on the substrate, temperature, relative humidity and plant growth as all of these factors affect the rate of water loss from the substrate. Typically, the surface of the root substrate should be allowed to dry slightly between irrigations. Over-watering of greenhouse crops is most often a result of irrigating too frequently and not teh volume applied at a given irrigation. Water quality must also be considered. This is because water quality or chemical characteristics (i.e. pH, alkalinity, mineral element content, etc.) of water used for irrigation and fertilization will significantly affect the chemistry of the substrate.
