Home FAQ Hydroponics What is pH and why is its value important for plants ?

 

The pH indicates the acidity or alkalinity of the solution. The pH should be kept between pH 5.5 and pH 6.5 to enable all elements in the nutrient solution to be available to the plants.

Most plants, except sweet peppers, release alkaline bicarbonate ions into the nutrient solution when nitrate is taken up. Some of the bicarbonate ions are neutralised by the sulphate salts in the solution. If the solution becomes too alkaline then acid must be added (phosphoric, nitric or citric ).

Under some conditions if the pH remains below 5.5 then alkali must be added to the solution ( potassium hydroxide, potassium carbonate, bicarbonate of soda ).

If the pH falls below 4 root death will occur. If the pH remains above 7 the leaves of the plants will turn yellow because the plant finds it difficult to absorb iron ( Fe ) when the roots are in an alkaline solution.