Key takeaways
- The Truckee Meadows Water Authority recommends sprinklers for turf and drip irrigation for trees, shrubs and flowers.
- Most of a tree's fine, water-absorbing roots are in the top 6 inches of soil, where machines and sod cutters work.
- Do not pile fill soil over tree roots.
- Mulch 2 to 4 inches deep under the drip line is the ISA's alternative to turf under trees.
Water-saving lawn conversions are good for the aquifer and the water bill. They are hard on trees that never had their own water supply.
Why do trees suffer when the lawn goes?
Many yard trees get most of their water from lawn sprinklers that run on a short cycle. Take the lawn out and those sprinklers go too, but the tree's roots are still looking for water in the same place. The TMWA landscape guide points out that in a water-efficient yard sprinklers are used for turf, which can be the most water-intensive part of a landscape, while drip systems are recommended for trees, shrubs and flowers, planned in water zones. It also notes summer water use is about four times winter use because of outdoor irrigation, and that our annual rainfall averages seven inches.
A tree that depended on lawn water needs its own water plan before the lawn goes. Read watering mature trees in the high desert.
What should happen to the soil and roots?
The ISA says the majority of a tree's fine, water-absorbing roots are in the top 6 inches of soil. Scraping sod with a machine near a tree, tilling or trenching for new irrigation lines can cut or expose those roots. Use hand tools near the trunk, keep trenches out of the root zone where you can, and place drip emitters under the canopy, out from the trunk, where the fine roots are.
The ISA also warns that fill soil added around existing mature trees can reduce soil oxygen and suffocate roots. Do not bring in soil or rock base to raise the grade under a tree. See trenching and grade changes near trees.
What goes under the tree instead of turf?
The ISA's preferred alternative to turf around trees is mulching, with a 2 to 4 inch layer of wood chips, bark or other organic material over the soil beneath the drip line. Keep mulch off the trunk, and avoid mulch volcanoes. The ISA says too much mulch can harm trees.
In fire country, check your fire district before choosing mulch near the house. The Living With Fire guide limits wood mulch to about an inch deep in the lean, clean and green zone and asks for none in the first 5 feet. See what is defensible space and free wood chips: uses and limits.
How do I watch for trouble?
Watch the tree after the conversion: smaller leaves, early fall color, thin crowns and dieback in the top are signs the tree is stressed. The ISA suggests checking new leaf or bud formation, leaf size, twig growth and absence of dieback. If you see them, call an arborist before the next summer. See drought stress and dieback.
Can you help?
We remove trees that fail after a conversion, but our first suggestion is a consultation before the work. A certified arborist can look at which trees will lose water and how the root zones sit. Call 775.232.8243 or request a free estimate. We do not design irrigation systems.
Sources
- Truckee Meadows Water Authority: Water Efficient Landscape Guide (read October 17, 2026)
- International Society of Arboriculture, Trees Are Good: Trees and Turf (brochure) (read October 17, 2026)
- International Society of Arboriculture, Trees Are Good: Proper Mulching Techniques (brochure) (read October 17, 2026)
- University of Nevada, Reno Extension: Living With Fire Defensible Space Guide (SP-23-07) (read October 17, 2026)