Hydroponic pH Modifiers affect Plant Growth and Nutrient Content in Leafy Greens

Use of hydroponics is increasing because of its ability to be used for year round vegetable production using an environmentally sustainable system. Management of solution pH is an important challenge in hydroponics systems. Our objective was to quantify the effects of various pH modifiers on growth and nutrient uptake of leafy greens and stability of nutrient solution’s pH. Lettuce, basil, and Swiss chard were transplanted into an Ebb and flow system, and nutrient solution pH was maintained using three different pH modifiers (pH Down, lime juice, or vinegar). The nutrient solution’s pH was maintained between 5.5 and 6.5. pH Down resulted in the most stable solution pH and required the least amount of product used when compared to lime juice and vinegar. The cost of using phosphoric acid or lime juice was greater than that of using vinegar. Vinegar reduced the yield of all crops in comparison to pH Down. When compared to pH Down, lime juice reduced the yield of basil and Swiss chard but not that of lettuce. Therefore, growers can use lime juice as an alternative to pH Down in lettuce production but not for basil and Swiss chard, while vinegar would not be recommended for any of the crops studied.