May checklist
- Water mature trees deeply, to about 18 inches and out to the canopy edge
- Spread 2 to 4 inches of organic mulch (ISA), kept off the trunk
- Keep mulch and woodpiles out of the first 5 feet around the house
- Prune conifers while the early-spring window lasts
- Thin and separate shrubs and grasses in Zone 1, 5 to 30 feet out
- Have hanging or dead limbs removed from trees over structures
- Book brush mowing or lot clearing for large parcels
The Reno airport's mean temperature climbs 8.7 degrees from April to May, to 60.3 F, and Glenbrook rises 7.5 degrees to 48.1 F. Monthly precipitation at the valley stations is already only 0.5 to 0.7 inches, so the weather will not water your trees.
May weather at five stations
Precipitation is 0.51 inches at Carson City, 0.55 at the Reno airport and 0.61 at Minden, while Glenbrook still gets 1.34. Snowfall is down to 0.1 inches at the Reno airport and Minden. Fallon's 0.68 inches is the wettest of the valley stations.
| Station (elevation, ft) | Mean temp (F) | Precip (in.) | Snow (in.) |
|---|---|---|---|
| Reno airport (4,410) | 60.3 | 0.55 | 0.1 |
| Carson City (4,761) | 56.6 | 0.51 | 0.0 |
| Minden (4,709) | 55.2 | 0.61 | 0.1 |
| Glenbrook (Tahoe) (6,350) | 48.1 | 1.34 | no normal |
| Fallon (3,965) | 58.4 | 0.68 | 0.0 |
Station normals, not town averages. NOAA flags Glenbrook's temperature normals as reduced completeness and publishes no snowfall normal there.
What the trees are doing
Trees are in full leaf-out and putting on their main growth, and water demand rises quickly. A tree that is under-watered can fall behind within weeks. Signs include small leaves, early yellowing and thinning crowns; see drought stress and dieback.
Water and mulch
University of Nevada, Reno Extension's guidance is to water mature trees to a depth of about 18 inches, out to the edge of the canopy, with a thorough soaking instead of frequent shallow sprinkles. Mulch the root zone with 2 to 4 inches of organic material (ISA; UNR Extension says 3 to 4) and keep it off the trunk. Mulch belongs away from the house in fire country, since Living With Fire clears combustible mulch from Zone 0. See watering mature trees in the high desert.
Fire season prep
Defensible space is easier to build before the grass cures. Living With Fire describes Zone 1 as lean, clean and green, 5 to 30 feet from the building, and Zone 2 as reduced fuel from 30 to 100 feet. Ladder fuels, the low plants and limbs that carry fire into a crown, are a Zone 2 task. See ladder fuels and limbing up. Your fire district sets its own expectations, and the agency decides.
Valley versus lake
Around the lake, May is still early spring, so conifer pruning and fuel work run later. If you are not sure which zone you are in, ask the office. Free estimates are detailed and tailored to each property; call 775.232.8243 and ask for the fire-season work you want done. Our service list includes defensible space and fire mitigation, lot clearing, brush mowing and masticating.
Sources
- NOAA NCEI U.S. Climate Normals 1991-2020, monthly (Reno airport USW00023185, Carson City USC00261485, Minden USC00265191, Glenbrook USC00263205, Fallon Exp Stn USC00262780) (pulled October 17, 2026)
- University of Nevada, Reno Extension: Tips for Healthy Landscape Trees (read October 17, 2026)
- University of Nevada, Reno Extension: Living With Fire (SP-23-07) (read October 17, 2026)
- International Society of Arboriculture, Trees Are Good: Pruning Your Trees (read October 17, 2026)
- International Society of Arboriculture, Trees Are Good: Mature Tree Care (brochure) (read October 17, 2026)