Controlling Powdery Mildew and Weeds in Florida Mulch Beds

White powdery growth under mulch is likely powdery mildew, fueled by excess moisture and large mulch particles that trap humidity.

Fixes

• Switch to fine mulch (¼–½ inch) for better airflow.
• Reduce irrigation; petunias prefer drier conditions.
• In rainy areas, move petunias to containers with drainage.
• Apply fungicide labeled for ornamental mildew if needed.

Weed Prevention

Pre-emergent herbicide in early spring + 2–3" fine mulch + prompt hand-pulling keeps beds clean.