I planted marigolds (large yellow ones) and they were doing great, but now the blooms are turning brown and dying. The plants are fine, it's just the blooms. We have 90 degree temps and heavy rain showers. Would this be the reason? I also sprayed with Sevin due to beetles.
Marigold Blooms Turning Brown
Pinch off or cut off all spent flowers. This is called deadheading. You are removing the finished product (seeds) and the plants think they have completed their growth cycle. If deadheaded, they will produce new flowers.I don't use chemicals so can't help you re Sevin dust. A person kills all the beneficial bugs that often take care of the bad guys and my personal feeling is that chemical use can just cause a new set of problems to the garden and our environment. Marigolds are seldom bothered by any insects.