WUCOLS Made Easy

A New Tool Lets You Quickly Find The Water Use Requirement for California Landscape Plants

Waterwonk.us Title

California laws and regulations require all new planting plans to be designed using hydrozones. All plants in a hydrozone must have the same or similar water use requirements. If you are preparing for the California Supplemental Exam for landscape architects, you need to know all about hydrozones and the California Model Water Efficient Landscape Ordinance.

The WUCOLS manual assigns each plant a water use category based on its water use requirements in the landscape in different parts of the state. In addition to classifying plants based on the water they needed, each water use group received a numerical coefficient.

  • High Water Use Plants = 70-90% of reference evapotranspiration
  • Medium Water Use Plants = 49-60% of reference evapotranspiration
  • Low Water Use Plants = 10-30% of reference evapotranspiration
  • Very Low Water Use Plants = <10% of reference evapotranspiration

The plant factor can be used with Landscape Coefficient Method to estimate water use of plants and develop irrigation schedules that would adequately water the plants. By only irrigating with the amount of water the plants need, the states precious water resources can be conserved.

Selecting Plants for Hydrozones

Have you ever been in a hurry to throw together a plant list for different hydrozones and struggled with the clunky lists in the WUCOLS 2000 manual? If you are like me, you probably get frustrated trying to find a low water-use groundcover for coastal southern California in a hurry among the “one-size-fits-all” list of plants.

Until now, the Water Use Classification of Landscape Species (WUCOLS 2000 manual) has been the “bible” of California landscape plant water use requirements.

However, we don’t need to suffer through this excruciatingly painful process anymore. I found a new tool that makes finding the water use requirement of landscape plants exceedingly quick and painless.

WaterWonk.us WUCOLS Database

WaterWonk.us is a new, web-based tool that makes finding the perfect plant as easy as possible.

WaterWonk.us is a database that makes it easy to find plants with certain water needs based on the plant type and project location.

Let’s walk through the process for creating a low water use plant palette for coastal Southern California using the waterwonk.us web app.

waterwonk.us start screen

Step 1: Select Your Project Location

Your project’s location determine’s the site’s evapotranspiration rate. Select your site’s location. You can use the city’s name or the general geographic region.

Waterwonk.us select your project site location

Step 2: Search for Plants

Use the easy-to-use check boxes to select the type of plant that your want to use. You can search for a particular plant by name or use the check boxes to generate a list of ideas.

waterwonk.us plant selection screen

This is an example of the search results you get when you search for California native, low-water use groundcovers.

Waterwonk.us plant search results for low-water use groundcover

Step 3: Add Plants to Your Plant List

Click the check box to add the plant to your plant list. This is an easy way to generate a plant palette. You can add plants from multiple searches into one list. It is really easy to pull together a list of plants in a few minutes.

Plant Palette generated from waterwonk.us

Step 4: Download Your Plant List

After you assembled a plant palette using the WaterWonk.us web app, download the list to your favorite spreadsheet program. After you add any additional notes, you can paste the plant palette into your planting plan.

Waterwonk.us download plant list

WaterWonk.us Is A Powerful Tool for California Landscape Architects

WaterWonk.us is the best way that I have found to select plants based on their WUCOLS water use classification. It is easy to select plants based on their water use and role in the landscape. I highly recommend WaterWonk.us to any landscape architect or garden designer. This nicely executed website will save me hours of valuable time when I need to generate a plant palette and is a huge improvement over the WUCOLS 2000 manual.


John is a landscape architect who is currently preparing to take the California Supplemental Exam to become licensed in California. He is currently a licensed professional landscape architect in Georgia and Florida. John graduated from California State University, Pomona with a BSLA degree in landscape architecture in 1997 and has extensive practice experience in residential and commercial landscape design.

Posted in Irrigation, News, Plants, Tools and Resources, Water Tagged with: , , , , , , , , , , ,

Do You Want to Pass the CSE?

You are in the right place. Learn what you need to pass the California Supplemental Exam for landscape architects the first time. This site is dedicated to aspiring landscape architects who want to get a California landscape architect license. I'll share my research for the CSE as I prepare for the exam.

Feel free to submit a question and I'll do my best to answer it here.

Good luck,

Ask Me A Question

Your message was successfully sent.
Thank You!