Because I adopted a tree from Tree New Mexico they sent me the advice below.

It indicates that young trees need a lot more care than most of us understand.

I imagine much of the advice applies to trees of any age.

#VivaNobHill

Gary

SUMMER TREE CARE
- Please water your young trees 3 times per week, low and slow to a depth of 18-24". Move the hose around the tree to several locations. Newly planted Trees need to be watered consistently for at least 3 years!
- Add more mulch to keep the roots cool.
- Pull back weed barrier to allow water to penetrate down to the roots (5ft from the tree is recommended).
- Remove the stakes if your tree is a year old.
- Never use weed killer near your trees!