When you say flush do you mean to put the whole plant the toilet and use that water to clean out the overdose? What about fecal remnants and powdery mildew? A friend of mine told me to keep the seat to my toilet down because powdery mildew lives in toilets and my plants could become infected.
Maybe your soil is bad. I add left over refried beans to my soil because I heard that it adds amino acids and things of that nature. I also make a compost tea from the diapers of the baby next door and my plants rock. Only use cloth diaper because the modern diapers swell up with water and get all gnarly and gross.
