The pH Scale
What is pH and why is it so important to our plants? pH is a measure of acidity or alkalinity of a solution. It is important to your plants because when the pH is correct your plants can uptake all their food and when your pH is off your plants may starve.
There is a much more complicated definition of pH but not needed for this explanation. pH solutions with measured at less than 7 are said to be acidic, and solutions with a pH greater than 7 are alkaline. pH of 7 is referred to as neutral.
Plants generally grow most efficiently when their pH levels are in the 5.5 to 6.5 range due to the presence of helpful nutrients. Extreme fluctuations in higher or lower pH can cause deficiency or toxicity of these nutrients. This is especially true when using synthetic based pH solutions and running any type of hydroponic system, soilless, or cocoa-based garden.
On the other hand when you are running a complete mineral based organic fertilizer like General Organics (GO) adjusting pH is not necessary according to the footnote on the GO feeding chart. That said, I have customers that run GO, who do not pH and customers that do pH their solutions. Either way having a pH meter in your toolbox is a very good idea and for my money I use only BlueLab meters. Those that run a super soil recipe genuinely do not pH prepared solutions but do check the pH of their grow media using a pH meter for soil.