Answer: The corn gluten meal works on seeds when they try to germinate so it should not affect already established plants (or already germinated weeds). If however you tried to grow your flowers from seed then it could inhibit their germination just as it does that of the weeds. If you are mulching your flower beds with several inches of organic mulch then you should not be having too much of a problem with weeds grminating with or without the corn gluten meal because the muclh should smother the weed seeds. I hope this helps.
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