Why Your Zinnias Have Powdery Mildew
Zinnias get powdery mildew in humid, stagnant air. Prevent it with airflow and spacing. Treat with milk spray.
Signs
- White, powdery spots on leaves
- Starts on lower leaves
- Spreads upward
- Leaves yellow and drop
Why Zinnias Are Vulnerable
- Dense foliage
- Poor airflow
- Humid conditions
- Overhead watering
How to Treat
- Remove affected leaves.
- Improve airflow. Space plants.
- Milk spray. 1 part milk + 9 parts water.
- Neem oil. Evening spray.
Prevention
- Space 9-12 inches apart
- Water at soil level
- Choose resistant varieties
- Don’t crowd
Common Questions
Will powdery mildew kill zinnias? Rarely, but it weakens them.
Can I still cut flowers? Yes, if they look healthy.
Does milk spray really work? Yes. Use within 2 days.
Will it come back? Yes, if conditions stay humid.
What about resistant varieties? Some zinnias are resistant. Check packets.
Should I remove the whole plant? Only if severely affected.