Treating high blood pressure with suppliments

Patient: I have high blood pressure,140 over 94, and I’m taking only vitamins,magnesium and potassium to bring it down, no man-made drugs.Also I’m exercising and eating foods to lower BP. I would like to take 2000-3500 mg of potassium a day, but do I need to have my blood tested to make sure I don’t take to much potassium?