The Recommendations Report to the Legislature on Landscape Water Use Efficiency by an Independent Technical Panel on Demand Management Measures was presented to the California legislature last May. One of the most sweeping recommendations the panel made is to amend California state law to require plant labeling regarding water-use requirements.
The panel noted that current horticultural references providing water use information cite personal experience of the expert author, not “field-based research.” Statistical research on water use for ornamental plants in California is lacking. “There is no legal or scientific authority that provides landscape water use requirements of ornamental plants in California,” report authors wrote.
The state’s Model Water Efficient Landscape Ordinance (MWELO) references Water Use Classification of Landscape Services (WUCOLS) , a database developed by horticulture and landscape professionals who served on committees that represented various regions in the state. The Panel notes that WUCOLS has 3,546 plants, but less than 6% have been “scientifically researched for water use.” Many plants sold in the state aren’t on the list at all.
Data in the list on plant water use was made by consensus agreement of 36 horticulture professionals from the state’s six climatic zones. The qualitative assessment bridges the gap for industry until quantitative research can be conducted.
The idea behind improving the scientific base is to be able to document plants’ water use prior to planting the landscape. MWELO includes requirements that plants be chosen based on water use and has a “Maximum Applied Water Allowance.” The updated ordinance requires a third party audit that covers the landscape, including plants.
The panel recommends that all plants sold in California are labeled at point of sale by water use (low, medium, high) by the WUCOLS, scientific research or the California Department of Water Resources. To accomplish the goal, the panel proposes that the Department of Food and Agriculture modifies Regulations for Nursery Stock Grades and Standards to label ornamental plants correctly, including water use.
NewTerrain August 29, 2016.