Q: I went out to water my hydrangeas today and noticed white spots all around the edges of the leaves. This was not there yesterday so it happened sometime during the night. The leaves don’t seem damaged and the plants still looks healthy. The spots seem to be predominately on the top leaves and the foliage beneath them is relatively unaffected. Honestly, it looks like white bird poop all around the edges.

A: These are fascinating pictures!

My guess it that it’s the remains of pollen or something else in the air that fell on the leaves in a light rain. It might also be the remnants of plant sugars and salts exuded by the young leaves.

The rain wasn’t hard enough to completely wash the leaves so the particles accumulated at the leaf edges and when the water evaporated, this white stuff was left.