Tree Watering Guidelines

How should trees be watered in this region?

In general, we should infrequently yet deeply water our trees in the most water-efficient way possible. Additionally, use top mulch to preserve moisture around your tree’s root zone.

Consider 4 elements when watering your trees:

  • Method of water application (e.g. sprinklers, drip systems)
  • Duration of application (how much water and for how long?)
  • Frequency of application (how often?)
  • Location of application (where to water?)

Each element should be tailored to the age, species, and environment of your tree. You can use use the Canopy Tree Library to see whether your tree has low, moderate, or high watering needs.

Tree Type Frequency Drip
Run time
Run time
See: Caring for Mature Native Oaks
Mature tree with low water needs Once or twice
in the dry season
90 minutes 45 minutes
Mature tree with moderate water needs, and young trees Every other month 90 minutes 45 minutes
High water needs (Thirsty trees) Monthly 90 minutes 45 minutes
Newly planted trees See Caring for Young Trees

May to October generally has almost no rainfall. If spring or fall is unusually wet or dry, irrigate accordingly.

Notes on Drip Application:

  • This chart assumes drippers are placed approximately 3’ apart, with an application rate of 1 gallon per hour (GPH).
  • Soaker hoses have variable output. Check depth of watering and adjust time as necessary to water tree to a depth of 18 – 24” for most mature trees.
  • Top mulch should be applied over drippers to a depth of 3 – 5”

Notes on Sprinkler and Bubbler Application:

  • Drip and soaker hoses are always preferred over spray irrigation because they are more water efficient (less water loss to run-off or evaporation).
  • If you are using spray irrigation, use only 1″ of top mulch so that water can still penetrate.
  • If using conventional spray nozzles, split sprinkler irrigation into two times separated by one hour: for example, two 20-minute applications equal one 40-minute application. This will reduce run-off and give the water time to soak into the soil between applications.
  • Conventional spray heads apply approximately 2.0 inches of water per hour.
  • Replace nozzles with water-efficient nozzles, which will save water and reduce runoff. One start time is adequate with this method.
  • Higher flow bubblers are recommended for newly planted trees to achieve even coverage. Install 1-gallon-per-minute (GPM) emitters. Maintain a solid watering basin that can hold 10 to 15 gallons. If necessary, split run time so water does not overflow the basin.