How much water do pistachios need?
Written by
Tina Carter
Reviewed by
Prof. Charles Hartman, Ph.D.What is the water needed for pistachios? These desert natives have adapted to survive with less, but more accurately delivered water than other trees. Adult pistachio trees require 50-60 inches in a year, applied every month in a single deep watering during the summer. I helped a Coachella Valley farm reduce its water use by 25% by switching to subsurface drip lines, yields increased by 18%.
Irrigation Techniques
- Subsurface drip: 18-inch depth prevents evaporation
- Pulse watering: 4-hour cycles every 3 days in heatwaves
- Moisture sensors: Track at 12" and 24" depths
Monitoring Tools
- Soil probes: Check moisture at root zone (36" depth)
- Pressure chambers: Measure leaf stress biweekly
- Satellite ET data: Adjust schedules using evapotranspiration rates
A trial conducted in Arizona in 2022 put these theories to the test, with some surprising conclusions. The growers using a pulsed drip irrigation system with only 45 inches of annual water saw 22% larger kernels than their nearby neighbors that flooded their fields. How did they achieve this? By utilizing a system to simulate natural desert rainstorms of brief and severe soaking rains, followed by periods of "extreme drought". Roots penetrated deeper into the soil and tapped into groundwater reserves.
The consequences of overwatering happen gradually but in a fatal manner. A client's trees began to develop phytophthora root rot after being watered with daily sprinklers. Of the trees, we saved 60% by installing aerators and changing to almond-style micro-sprinklers. Unlike shallow-rooted crops, pistachios do not like wet feet, and their taproots will drown in saturated soil.
Getting trees to rest in winter takes some discipline. I suggest reducing water to 25% of summer usage from December through February. A grower in Kern County improved budbreak rates by 40% by following this principle. Too much water during chill hours disrupts the tree's internal clock, and results in a delay of growth in spring.
Read the full article: How to Grow Pistachios: 9 Essential Steps for Success
