After 18 years of frustration with pH and what it means or doesn't mean, it now seems that pH has little to do with nutrition of plants growing in containers! ... The fiction about pH and the containner system is further confused by publications which claim that micronutrient availability decreased as pH increased. It is true that available iron and manganese decreased as the pH of the container growth medium increased. However, it is false to say that the pH level decreased the availability of iron and manganese. Peterson added increasing quantities of calcium hydroxide to raise the pH. It was, in fact, the increasing quantity of calcium that caused the decreased availability of iron and manganese; increased pH was merely a symptom. The pH increased du to the calcium but to blame the pH for the decrease in micronutrient availability instead of the calcium is an error in the interpretation of the results of the experiment.