Water on hydrangea leaves in full sun

Asked July 13, 2018, 3:07 PM EDT

It has been my experience that many bedding plants', particularly hydrangeas, leaves will burn if you get water on them in the full light of the sun. I have been in a "rousing" discourse with my fiance about this as he does not believe any harm will come to the leaves if they get water on them during a full sun day. There are many websites that say it is a myth that water on the leaves will cause them to burn in full sun. I am finding this to be very frustrating as I have, in the past, caused the burn to occur by getting the plants wet in full sun....I know what I saw. My fiance is wanting to hear what the master gardeners have to say about the subject in order to put the issue to rest. I have to say that I am about ready to go outside and sprinkle my beautiful hydrangeas in the full sun, just to prove it to him. I will honor whatever your answer turns out to be. Thank you.

Lane County Oregon trees and shrubs irrigation and water management horticulture

1 Response

Water on leaves in the sun won't cause burn. As often happens, there is more to say on the subject. "There are many causes of leaf scorch, but irrigation with fresh water is certainly not one of them," according to the Washington State University Extension publication The Myth of Hot-Weather Watering https://s3.wp.wsu.edu/uploads/sites/403/2015/03/leaf-scorch.pdf
What more is there to say? Quite a bit. The details matter, and understanding leaf scorch is critical. Irrigation water with too much salt can cause damage. Many folks don't water in time, and the scorch has already happened, so watering in the sun is blamed.
Watering and the actual temperatures matter a lot. Many of us will have scorched plants after this heat wave. Even if watered appropriately, the temperatures are just too high for some plants, especially those with thin leaves. Rigging temporary shade, like cardboard or patio chairs placed over delicate plants can help. I have a friend who mounts pretty rain-type umbrellas along her deck rail to shade the hydrangeas in July.
I hope your hydrangeas survive well this summer, whenever you choose to water them.