I kept my rosemary pot on the kitchen windowsill just for fresh sprigs: within weeks, a white film appeared and I understood what the glass was trapping
That white coating on your rosemary isn’t dust—it’s powdery mildew thriving in the exact microclimate your kitchen window creates. The glass pane itself is the culprit, trapping humidity and blocking airflow while amplifying temperature swings. Learn why and how to reclaim your windowsill herb garden.