Guide to Estimating Irrigation Water Needs of Landscape Plantings

Introduction
Water conservation is an essential consideration in
the design and management of California landscapes.
Effective strategies that increase water use
efficiency need to be identified and implemented.
One key strategy to increase efficiency is that of
matching water supply to plant needs. By supplying
only the amount of water needed to maintain
landscape health and appearance, unnecessary applications
that exceed plant needs can be avoided.
To do so, however, requires some knowledge of
species needs.
This Guide provides irrigation water needs evaluations
for over 1,900 species used in California landscapes.
It is based on the observations and field
experience of 41 knowledgeable landscape horticulturists
in California (see list of Regional Committees).
It was developed to provide guidance in
the selection and maintenance of plants based on
irrigation water needs. Specifically, it can be used
to:
• assist landscape architects, designers, and planners
in selecting plants for water efficient landscapes,
• assist landscape managers in evaluating water
needs of existing plantings and in creating irrigation
schedules that match species needs,
• provide options for landscape managers who wish
to create hydrozones, i.e., to change species composition
to reduce wide variations in water needs
within plantings, and
The WUCOLS guide provides water needs evaluations for over
1900 species. Plants can be selected according to their water
needs and grouped into water conserving hydrozones.
• provide a basis for estimating water needs for new
landscapes.
The project was initiated and funded by the Water
Use Efficiency Office of the California Department
of Water Resources. Work was directed by the University
of California Cooperative Extension (San
Francisco and San Mateo County office). The first
edition of the Guide was completed in 1992. A second
edition was published in 1994, and this third
edition was completed in 1999. In each edition, additional
species evaluations have been included. The
third edition was funded by the U.S. Bureau of Reclamation.
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