What are WUCOLs? The Basics of Plant Water Needs

The WUCOLS list helps pros and clients alike understand water needs of plants.

​What are WUCOLS? Perhaps you have puzzled over this term when beginning a new landscape. The term stands for Water Use Classification of Landscape Species. Landscape designers in California use this term with clients when discussing plant water needs and irrigation design.  Or a WUCOLS list could show up on your landscape plan, typically as a column in the plant legend.  Or, if you live in a highly regulated city, you may just have to produce a WUCOLS list for the city planning department in order to proceed with your landscape.  Before turning and running for the nearest exit, reassure yourself that the work of determining WUCOLS in a landscape has already been done for you and can easily be found online.
Here are 10 basics to know about WUCOLS: 

• The WUCOL list assigns a letter to each plant species based on its water needs: very low, low, medium, and high.
• These classifications are specific to California and often change depending on region.
• As you probably guessed, the WUCOLS list originated in response to drought.
• Over 3500 plants are found on the list, you can easily make you entire landscape from this WUCOLS list.
• The list is now in its fourth edition, completed in 2014, with 1500 additional species, hybrids, and cultivars listed than found on the previous edition.
• Nearly all the plants were evaluated by 36 horticulturalists working throughout California.
• The data base does have a search option or the database can be downloaded.
• The goal of the project is to not only lower water usage but to also help create efficient hydrozones, i.e., irrigation zones where species with the similar water needs can thrive.
• The ratings of species vary depending on region. (Central Valley, low desert, etc.)
• Turfgrasses are also rated, but not by region.

There is a lot of great information related to plant water needs and irrigation on the site, so check it out:  WUCOLS IV Plant List

---