Most desert plants die from watering that's too shallow and too frequent, not from too little water. The goal is to water deeply and less often, so roots grow down where the soil stays cool.
1. Water to the right depth (the 1-2-3 rule)
Groundcovers, cacti, flowers1 foot deep
Shrubs2 feet deep
Trees3 feet deep
Check it: about an hour after watering, push a soil probe (a long screwdriver or piece of rebar works) into the soil. It slides easily through wet soil and stops where the water stopped. If it stops short, run your system longer.
2. Run drip long enough
- Drip run times are typically 2 hours or more per watering. Two to six hours is common.
- Example: a tree with a 5-foot-wide canopy needs about 22 gallons. With three 2-gallon-per-hour emitters, that's about 3½ hours.
- Put emitters along the drip line, the outer edge of the canopy, not against the trunk.
- Between 6 months and 1 year after planting, move emitters farther out as the roots spread. Add emitters as the plant grows.
3. New plants: water often, then stretch it out
| Weeks after planting | Summer | Fall – spring |
|---|---|---|
| Weeks 1–2 | Every 1–2 days | Every 3–4 days |
| Weeks 3–4 | Every 3–4 days | Every 6–7 days |
| Weeks 5–6 | Every 4–6 days | Every 7–10 days |
| Weeks 7–8 | Every 7 days | Every 10–14 days |
After week 8, keep stretching the time between waterings until the plant is established.
4. Established desert plants need much less
- After their first summer, low-water-use trees and shrubs rarely need water more than once a week, even in summer, and far less in winter.
- Adjust your controller at least four times a year, as the seasons change.
- Desert-adapted trees in spring often go 14–30 days between waterings.
- Thirsty plants such as citrus, roses and hibiscus need water more often than desert natives like palo verde, Texas sage and penstemon. Put them on a separate valve if you can.
5. Smart habits
- Water at night or before sunrise, when less water evaporates.
- If you get ½ inch of rain or more, skip the next watering.
- Every 6–12 months, water twice as long as usual once to flush salts below the root zone.
- In the hottest months, most yards don't need watering more than twice a week.
For seasonal charts by plant type, see the watering guide from Water – Use It Wisely, linked below.
Sources
- Water – Use It Wisely: Plant Watering Guide
- AMWUA: Watering Schedules
- City of Phoenix: Save Water Pledge
Last checked Nov 5, 2026. Programs and rules change; confirm with the source before you act.