Key takeaways
- Water regularly in the growing season to 18 inches deep, out to the edge of the canopy (UNR Extension).
- A thorough soak is much better than shallow, frequent watering.
- Mulch 3 to 4 inches of organic material across the root zone, kept 6 inches from the trunk.
- Never put sheet plastic under mulch; it can kill roots.
- Stressed trees need a look from an arborist, not more water by guess.
Reno gets about 9 inches of precipitation a year, and Minden about the same. Our big shade trees were planted on lawns and irrigation, not on rain. When the lawn is replaced or the irrigation changes, the trees notice.
Our climate in numbers
The NOAA 1991 to 2020 normals put precipitation near 9 inches a year in Reno (9.24 inches at the Reno 1.4 NNE station) and 9.34 inches at Minden, and 11.7 inches at Virginia City at about 6,340 feet. These are desert numbers. A mature tree on a lot that is not irrigated is living on much less water than its species evolved with.
Most established landscape trees in our valleys depend on the lawn, drip lines or flood irrigation around them. If you convert turf to rock or wood chips, check what the trees will get after the change.
How deep and how wide should you water a mature tree?
University of Nevada, Reno Extension's advice for landscape trees is to water regularly during the growing season to a depth of 18 inches, out to the edge of the canopy. Many people water close to the trunk, but the roots that take up water are mostly out toward and beyond the drip line.
Extension's planting guide adds that a thorough soaking is much better than shallow, frequent watering. Shallow watering keeps the roots near the surface where the soil dries and heats first. For drip systems, make sure there are enough emitters; Extension suggests at least four emitters per tree for newly planted trees, and larger trees need more coverage.
How to check what you did
A soil probe, long screwdriver or a rod of rebar pushes easily into wet soil and stops where the soil is dry. Test a day after watering. If it stops at 5 inches, the soak did not reach 18. Adjust the run time, not the frequency, and check again.
We do not publish a schedule of days and minutes, because it depends on soil, exposure, species and the emitters. Extension itself gives no single schedule for the same reason.
How should you mulch a tree?
Extension recommends 3 to 4 inches of organic mulch over the planting area, kept 6 inches from the trunk, and no sheet plastic under it, which can kill tree roots. The ISA says the recommended depth is 2 to 4 inches, with coarse arborist wood chips at 3 to 4 inches, applied near but not touching the trunk and out to the drip line if practical. A ring of at least 3 feet in radius is the minimum for most trees.
Mulch piled against the trunk, called a mulch volcano, softens the bark and can lead to stem-girdling roots. Pull it back so the base of the trunk shows.
Signs a tree is short of water
- Leaves that scorch, curl or drop early in summer
- Thin crowns or dead twigs at the tips
- A tree that was fine and declines after a landscape or irrigation change
- Dead branches in the upper crown
These can also point to roots, pests or decay. Water stress is a common cause but not the only one. See drought stress and dieback.
When to call
If a mature tree is declining, call for an assessment. A certified arborist can tell you whether the issue is water, structure or something else, and whether pruning, support or removal is the right answer. Battle Born Tree Service has two ISA Certified Arborists on staff, including ISA Certified Arborist WE-11728A. We do not offer fertilizing or pest treatment, so water and mulch are the care points we can help you decide on. Ask about our arborist consultation.
Sources
- University of Nevada, Reno Extension: Tips for Healthy Landscape Trees (read October 17, 2026)
- University of Nevada, Reno Extension: Planting Trees in Northern Nevada Landscapes (read October 17, 2026)
- International Society of Arboriculture, Trees Are Good: Proper Mulching Techniques (read October 17, 2026)
- NOAA National Centers for Environmental Information: U.S. Climate Normals 1991-2020 (retrieved October 1, 2026)