Planted these about a month ago. They did fine at first, but now every bloom turns black while starting to open and then never flowers but dies instead! They are planted around my outside pole light. Not sure if that would have anything to do with it ( the electricity?). The flowers still have buds, but I'm thinking of taking them out since they won't bloom! Help!!
To discourage plant diseases be sure to water the soil, but avoid the foliage and SUN SUN SUN!
Zinnia's need plenty of sunshine, warm temperatures and even watering.
They can be effected by some pests and diseases, including Powdery Mildew and blossom blight.
Fungal infections can cause brown spots or as you describe, the buds could darken and be effected.
Damp conditions or lack of air circulation can be a cause of disease.