|For the past 2 years my marigolds, growing beautifuly, open very nice, then rot appears in the center.
|If the flowers are spent, or if they get oversaturated with water when they're old, Marigold flowers can rot in the center. The best course of action sf to pinch or cut the flowers off before they begin to deteriorate. Make sure your Marigolds are planted in full sunshine, and try to keep water off the open blossoms. The more you pinch the plants back, the more flower buds they will develop, and the bushier the plants will be.