Why Is pH Important?

Soft Secrets
16 May 2019

What’s pH? This is a question that usually makes new growers scratch their heads and reach for the pipe. pH applies to the level of alkalinity or acidity of a given “thing”, in this case a liquid.


The liquid is the nutrient solution being used to grow your green. The pH scale starts at 0 and rises to 14. A value of 7.0 is considered neutral, with values over 7.0 being alkaline and values below 7.0 being acidic. The question that must be asked is why this is important. The nutrient solution is basically a cocktail of various chemicals. These chemicals can react to each other in a process called covalent bonding and form new chemicals that aren’t wanted. They’re not wanted because the plant can’t use them. This process of covalent bonding is largely dependent on the pH of the solution the chemicals are suspended in, in this case water. With the chemicals being used in your average hydroponic solution, a chemist would say that the optimum pH would be 7.0, which is neutral.

The reasoning behind this is that in keeping the solution neutral, covalent bonding of the constituent parts of your solution will be kept to a minimum. But since cannabis plants like a different pH level for optimum growth, lower the pH, and take the slight loss of nutrient value. Fast growing leafy plants generally like a lower pH in the range of 5.2 to 5.9. Fortunately, a lower pH will bond fewer nutrients than will a higher pH. If the pH value goes beyond the optimum range of 5.2 to 5.9, undesirable levels of nutritional deficiency and toxicity will occur, both of which can seriously impede plant growth. Be vigilant. In researching the various hydroponic methods in use, it might have been noticed that most of the growing media in use is relatively inert (rockwool, pea gravel, sand, etc.). That is, the growing medium won’t react with the nutrients in the solution. For those methods that use inert media, a pH of 5.2 is recommended for optimal elemental uptake. It is at this pH level that the roots will assimilate the nutrients in the solution most efficiently. If the root has to work less to assimilate the required nutrients, the rest of the plant will benefit.

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Soft Secrets