My grandmother used to tell us not to water plants when the sun was shining -- to wait until evening to water. My husband says I am crazy. He waters when the sun is high in the sky. What is the correct time to water or does it not matter?

There's a trade off, if you water in the evening then you increase the risk of fungal diseases because the leaves stay wet for longer. If you water when the sun is high you lose more water to evaporation (same thing if it's windy). Generally morning is the best compromise. There is an idea that if you water when the sun is high then the light is intensified through the water droplets and burns the leaves and that's why some people avoid watering when the sun is high. It's actually not true, if it was the leaves would get burned every time there was a shower followed by the sun coming back out. In reality if the plants are thirsty, you need to water them there and then whatever the sun is doing.

to NGA.

Welcome to NGA @Cramer

The risk of watering at night is that plant leaves stay wet which can promote fungus/mildew growth and wet attracts slugs and snails. Watering when the sun is high and hot can scorch leaves and the water evaporates faster. It is best to water deeply in the early morning so the plants have the resources to get them through hot weather. If early morning is not possible, then water before the sun sets so leaves have time to dry.

Of course, if you see plants that are wilting, it is absolutely okay to give them water. Just try to keep from soaking the foliage.

https://extension.illinois.edu...

This article explains why watering in the sun does not cause leaves to burn:

http://www.americanscientist.o...

Agree, any truly wilted plant needs a drink immediately.

Checking plants mid-day can be misleading if there is faux wilt. Some plants can look wilty during the middle of the day but not really be thirsty at all. Checking for wilted appearance in the morning is a more sure thing.

I usually water potted plants in the evening because I don't have time in the morning to do it before I take a shower before work. I don't get the leaves wet much when I do it that with a spouted watering can. Ground plants get a drink from the hose in the morning on the weekends if needed, ideally. Sometimes that ends up being done in the evening too.