Good afternoon Barbara,

We received your questions about lawn and tree watering. The optimal time to water is between 10 pm and 6 am. During this time the temperatures are generally lower, there is less wind and humidity is higher so there is less loss to evaporation.

Trees need to be watered when the top 4 – 6 inches of soil is dry. This can be measured by touch or inserting a long thin screwdriver into the soil. If the screwdriver easy goes into the soil to a depth of 6 -8 inches the soil has adequate moisture no water is needed. If the trees are in grassy area they may need additional water.

I have included some links to information sheets related to watering established lawns, water home landscapes during drought and watering mature trees: https://extension.colostate.edu/topic-areas/yard-garden/watering-established-lawns-7-199/
https://extension.colostate.edu/topic-areas/yard-garden/watering-a-home-landscape-during-drought-7-240-2/
https://cmg.extension.colostate.edu/Gardennotes/657.pdf

I hope this information is helpful. Feel free to contact us if you have additional questions.

Linda, Weld County Colorado Master Gardener