It is possible to use too much so go easy. One tble spoon sounds about right to me. Once visited a greenhouse where all the plants had lost all their roots. There was stacks of time release Epsom salts on top of each pot (The lady had hired an expert to take care care of them for a while) It looks like too much can cause micronutrient toxicity and do a good job of killing the roots. So easy with the stuff. More is not better.