The garden site received 4 hours of full sun and 4 hours of part sun and 2 hours of shade. I did not think that the part shade would affect the zinnias. My husband and I went on vacation and when we returned I had powdery mildew all over the leaves and stems of my zinnia plants.
Before our vacation the zinnias looked good growing along the river rock wall but they did not have enough air flow and they did not have enough full sun, plus our garden sitter watered all of the gardens at dusk.
My zinnias didn’t have a chance as the odds were against them. The following year I planted the zinnias in an open air garden that had 6 hours of full sun and the plants flourished.
|Thin out flowers to prevent powdery mildew: Image by Susan Golis|
Check your flower garden for overcrowding and thin out if necessary. Another way to prevent powdery mildew is to water your plants at the soil level with drip line irrigation or soaker hose. I water all of my plants in the morning before the heat of the day, I find that dusk or evening watering attracts garden pests.