Red roses in a cluster on a bush with green leaves
This rose, Petite Knock-out, is one of the roses that did well with minimal watering, according to research by a team led by Lorence Oki of the UC Davis Department of Plant Sciences. A new video by the nonprofit Pacific Horticulture profiles the project. (Courtesy Star Roses and Plants)

New video features Oki’s research

Climate-ready landscape research explained

The nonprofit organization Pacific Horticulture has released a new video describing research to develop irrigation recommendations for landscape plants, the science behind the process, and early ideas for mindful gardeners and landscapers. It features UC Davis Department of Plant Sciences horticulturalist Lorence Oki, the lead investigator on the project.

The video is Part 2 of a planned, three-part series describing the Climate Ready Landscape Plants Project. The project aims to answer the question: As climate grows increasingly extreme, what plants are best suited for planned landscapes in the American West?

Man wearing glasses. You can tell he's on a video call.
Horticultural expert Lorence Oki is a professor of UC Cooperative Extension in the UC Davis Department of Plant Sciences.

Spoiler alert: Researchers describe some surprises, including roses that look good with minimal watering.

The video describes some of the early results researchers are finding as they see how much water plants use in different situations – and how little water they need to survive. Researchers also are measuring how much the plants grow, how quickly they grow, how they react to dry conditions and how much water evaporates from their leaves. They’re working with plant breeders and people in the horticulture industry to see what might thrive in a wide variety of conditions.

The central goal of the project is to develop recommendations for irrigating these plants most efficiently. The researchers’ findings will help anyone planning to install or renovate a commercial or home landscape, as water becomes scarcer and poorer in quality.

In addition, people in California installing new landscapes or renovating some existing ones, must now stay within a state-mandated water budget – an effort to save water. But that means landscape architects, designers and installers must know how much water plants will use. The research aims to provide more of that information.

Project compares several ecosystems

The Climate Ready Landscape Plants Project started out as research for a master’s thesis in 2004, Oki explained. “It has expanded from one experimental field at UC Davis and is now in six fields in five states,” he said. “We just completed the first year of data collection at all of these locations and now have a boatload of data to process.”

The second field was started in 2017 at the South Coast Research and Extension Center in Irvine, part of the University of California Agriculture and Natural Resources network, where the UC Landscape Plants Irrigation Trials[LRO2]  started. This program focused on plant performance in southern and northern California locations. Since then, fields have been started at the University of Washington, Utah State University, Oregon State University and the University of Arizona, providing information from a variety of environments.

Researchers include Jared Sisneroz[LRO3] , a UC Davis alumnus who now is the project manager. Karrie Reid, also featured in the video, is a Department of Plant Sciences alumna and was an advisor for UC Cooperative Extension in San Joaquin County. (The project began with Reid’s master’s degree research.) Their work with Oki has included the performance of roses and many other landscape plants, including several California natives, when water is reduced.

A bush of long stems covered with green leaves and with small, spiky lavender flowers at the upper part of the stems.
This variety of chastetree -- Vitex 'Delta Blues' -- is one of the low-water landscaping plants that did well in the trials.

Watch the videos

The “Landscapes of Change” series documents stories of climate resilience in horticulture, landscape design, restoration and applied research.

Colleagues at Utah State University Extension have created a related video, "Climate Ready Landscape Plants."

More climate-resilience resources

Pacific Horticulture is a non-profit organization dedicated to promoting resilient gardens and their benefits to people and nature with science-based educational outreach.

The California Center for Urban Horticulture offers the Water Use Classification of Landscape Species (WUCOLS). You can enter the name of the plant you want to use to find out how much water it requires. The database gives information on more than 3,500 plant groups commonly used in California landscapes.

Agriculture and Natural Resources (ANR) is a statewide network of University of California researchers and educators dedicated to the creation, development and application of knowledge in agricultural, natural and human resources.

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