- Author: Saoimanu Sope
UC climate-ready landscape trials identify low-water yet attractive plants
Good news: roses can be a part of your water-efficient landscape. Lorence Oki, UC Cooperative Extension environmental horticulture specialist in the UC Davis Department of Plant Sciences, identified rose cultivars that remain aesthetically pleasing with little water.
Oki is the principal investigator of the Climate-Ready Landscape Plants project, which may be the largest irrigation trial in the western U.S., and the UC Plant Landscape Irrigation Trials (UCLPIT), the California component of that project. These projects evaluate landscape plants under varying irrigation levels to determine their optimal performance in regions requiring supplemental summer water.
“There are some assumptions that pretty plants use a lot of water, like roses,” Oki said. “Everyone thinks they need a lot of water, but we've found some that don't, and they still look great. A water-efficient landscape doesn't need to look like a Central Valley oak-grassland in the summer. It can look really attractive.”
In 2021, Oki's team at UC Davis identified Lomandra confertifolia ssp. pallida "Pom Pom" Shorty and Rosa "Sprogreatpink" Brick House® Pink as two of the best low-water plants in the trial. 
“The useful tip or information that is shared at the end of each trial is the selection and designation of plants as Blue Ribbon winners. These are the plants that looked good with an overall rating of 4 or higher throughout and were on the low (20%) water treatment,” said Natalie Levy, associate specialist for water resources, who manages the project at the UC ANR South Coast Research and Extension Center.
How plants earn a blue ribbon
Each trial year, the selection of new plants is based on research recommendations and donated submissions from the nursery industry. The landscape plants are trialed in full sun or 50% shade cover.
Irrigation treatments are based on the rate of evaporation and plant transpiration (evapotranspiration) measured through a local California Irrigation Management Information System (CIMIS) weather station that provides a reference evapotranspiration (ETo) rate.
Three levels of irrigation are provided to the plants equal to 20%, 50%, and 80% of ETo. The volume of water applied is the same at each irrigation based on soil characteristics, but the interval between applications varies with weather and the treatment. Using this method, irrigations for the 20% treatment are less frequent than the 80% treatment.
“The 20% treatment during the 2022 trial was irrigated an average of once per month while the 80% treatment was irrigated weekly,” explained Levy.
During the deficit irrigation trial, monthly height and width measurements are taken to determine the plant growth index. Monthly qualitative aesthetic ratings on a scale of 1 to 5 are determined for foliage appearance, flowering abundance, pest tolerance, disease resistance, vigor and overall appearance.
A second round of flowering abundance and overall appearance measurements are also taken to capture more of the blooming period. For example, UCLPIT identified in the 2020 trial at South Coast REC that the "Apricot Drift" rose had a mean overall appearance score of 3.5 out of 5, deeming it “acceptable to very nice” and a low water use plant within the Water Use Classification of Landscape Species or WUCOLS guide.
Project expands options for landscape planting
“(WUCOLS) only has 3,500 plants in it. There are guesses that there are close to 10,000 cultivars in urban landscapes in California, if not more,” said Oki. “WUCOLS also didn't have numerical ratings. Instead, you'll see verbal ratings like ‘low water use' or ‘high water use.'”
The UCLPIT project has not only developed numerical recommendations for irrigation, but it has also added new landscape plants that are compliant with California's Model Water Efficient Landscape Ordinance. In fact, UCLPIT's data is one of the few sources that can be used to supplement WUCOLS.
Geographic diversity of trial sites adds to knowledge base
In addition to UC Davis and South Coast REC in Irvine, the trials have expanded beyond California as the Climate-Ready Landscape Plants project and is in progress at Oregon State University, University of Washington, University of Arizona and Utah State University thanks to a USDA/CDFA grant awarded in 2020.
Lloyd Nackley, associate professor of nursery production and greenhouse management at Oregon State University, is the principal investigator of the trial in the Portland metro area, which is entering its third year.
“People know that there are drought tolerant plants, but there are many. We're trying to highlight lesser known or newer varieties. And even though the trial is three years, most gardeners would hope that their garden lasts longer than that,” said Nackley.
One of the observations that Nackley recalls is of the Hibiscus Purple Pillar plant. Unlike the trial at South Coast, the Purple Pillar did not perform well in Oregon in the spring.
“It wasn't until August that we saw the plant bloom and begin to look like what we saw from South Coast in April,” Nackley said.
Ursula Schuch, horticulture professor and principal investigator of the trial taking place at the University of Arizona, was also surprised at the range of performance among different plant types and the effects of irrigation, heat and temperature.
“This research will reassure green industry professionals that they can stretch their water budget to successfully cultivate more plants, watering them according to their needs instead of irrigating every plant according to the highest water-using plants,” said Schuch.
Although research is only conducted in the West, the hope is that there will be trials in other regions of U.S.
Doing so would yield comprehensive information about the plants and their performance in different climates. As extreme weather events persist in the U.S., disease pressure and risks do too. Trials throughout the country would provide location-specific data regarding disease susceptibility.
To learn more about the UCLPIT research project, visit https://ucanr.edu/sites/UCLPIT/
- Author: Kathy Keatley Garvey
The 12th annual UC Davis Biodiversity Museum Day, billed as "A Day to Celebrate Science," is set for Saturday, Feb. 18. Traditionally held during Presidents' Day Weekend, the event is free and family friendly. Parking is also free.
Biodiversity Museum Day chair Tabatha Yang, education and outreach coordinator for the Bohart Museum of Entomology, today announced that 11 museums or collections on campus will showcase their work:
- Anthropology Museum, 328 Young Hall and grounds, noon to 4 p.m.
- Arboretum and Public Garden, Shields Oak Grove, alongside the Vet School, Garrod Drive on campus, 9 a.m. to 1 p.m.
- Bohart Museum of Entomology, Room 1124 and Main Hall of the Academic Surge Building, Crocker Lane, 9 a.m. to noon and 1 to 4 p.m.
- Botanical Conservatory, the Greenhouses along Kleiber Hall Drive, 11 a.m. to 3 p.m.
- California Raptor Center, 340 Equine Lane, off Old Davis Road, 9 a.m. to 3 p.m. (tentative)
- Center for Plant Diversity, Sciences Laboratory Building, off Kleiber Hall Drive, 11 a.m. to 3 p.m.
- Nematode Collection, Sciences Laboratory Building, off Kleiber Hall Drive, 9 am. to 3 p.m.
- Marine Invertebrate Collection (Sciences Laboratory Building), noon to 3 p.m.
- Museum of Wildlife and Fish Biology, Room 1394, Academic Surge Building, Crocker Lane, 10 a.m. to 2 p.m.
- Paleontology Collection, Earth and Physical Sciences Building, 434 LaRue Road, to be determined
- Phaff Yeast Culture Collection, Robert Mondavi Institute Brewery, Winery and Food Processing facility, 10 a.m. to 2 p.m. (See news story)
Biodiversity Museum Day is considered a great opportunity to celebrate the diversity and variety of species on planet Earth and learn about the research being done at UC Davis. The event is also considered a great opportunity for scientists-to-be to consider their career options. Some of the museums and collections are open to the public only on Biodiversity Museum Day, Yang said.
- Author: Kathy Keatley Garvey
Scheduled Saturday, Feb. 18, is billed as a “free, family friendly educational event for the community where visitors get to meet and talk with UC Davis scientists and see amazing objects and organisms from the world around us,” according to Biodiversity Museum Day coordinator Tabatha Yang, education and outreach coordinator for the Bohart Museum of Entomology.
Yang today announced that 11 museums or collections on campus will showcase their work on Feb. 18:
- Anthropology Museum, 328 Young Hall and grounds, noon to 4 p.m.
- Arboretum and Public Garden, Habitat Gardens in the Environmental GATEway, adjacent to the Arboretum Teaching Nursery on Garrod Drive, 9 a.m. to 1 p.m.
- Bohart Museum of Entomology, Room 1124 and main hall of the Academic Surge Building, 455 Crocker Lane, 9 a.m. to noon and 1 to 4 p.m.
- Botanical Conservatory, the greenhouses along Kleiber Hall Drive, 11 a.m. to 3 p.m.
- California Raptor Center, 340 Equine Lane, off Old Davis Road, 9 a.m. to 3 p.m.
- Center for Plant Diversity, Sciences Laboratory Building/Esau Science Hall, off Kleiber Hall Drive, 11 a.m. to 3 p.m.
- Nematode Collection, Sciences Laboratory Building/Esau Science Hall, off Kleiber Hall Drive, 9 am. to 3 p.m.
- Marine Invertebrate Collection, Sciences Laboratory Building/Esau Science Hall, noon to 3 p.m.
- Museum of Wildlife and Fish Biology, Rooms 1394, 1371/1275, and main hallway, east end of first floor, Academic Surge Building, 455 Crocker Lane, 10 a.m. to 2 p.m.
- Paleontology Collection, 1309 Earth and Physical Sciences Building, 434 LaRue Road, 12 noon to 4 p.m.
- Phaff Yeast Culture Collection, Robert Mondavi Institute Brewery and Food Processing facility, 10 a.m. to 2 p.m. (See news story)
The UC Davis Biodiversity and Museum Day is traditionally held during Presidents' Day weekend. The 2022 event took place in the UC Davis Conference Center and drew some 1000 visitors. This year, it's back home to the individual departments where scientists will be on hand to greet visitors and answer questions.
All participating museums and collections have active education and outreach programs, Yang said, but the collections are not always accessible to the public.
Bohart Museum. The Bohart Museum, directed by Lynn Kimsey, UC Davis distinguished professor of entomology, is the home of a global collection of eight million insect specimens, as well as the live "petting zoo" and an insect-themed gift shop stocked with t-shirts, hoodies, books, posters, jewelry, collecting equipment and more. It was founded in 1946 and named for UC Davis professor and noted entomologist Richard Bohart.
Mulching Perennials
Trees and Shrubs
Trees and shrubs usually have an easier time getting through the winter if they are in good shape. However, if a freeze is forecasted, one of the most important things to do is to ensure they have been watered 2-3 days prior, especially if autumn has been dry. As with perennials, mulching with fallen leaves or other mulch will help protect the roots, but do not have mulch up against the tree trunk or plant stem, which could cause rot to occur.
Wrapping trunks of young trees with blankets, towels or piping insulation will provide added protection.
Bulbs
Wait until after the first frost, then gently dig up the bulbs or tubers. Cut away any leaves and brush off as much soil as possible. Let them dry out in a cool spot for about a week. Label them so you'll remember what they are! Pack them in a breathable box, such as a cardboard box, storing the bulbs so they don't touch each other, and cover them in sawdust or shredded newspapers. Keep them in a cool, dark location that is below 45°F, but doesn't freeze.
Citrus
Citrus plants can be protected by frost cloths which allow some light and air to penetrate and can stay on plants for a few days at a time. They can also lay directly on plant foliage. If you use other type of cloth such as burlap or cotton sheets, use stakes to hold the cloth away from the plant greenery. Remove it during daytime when temperatures are above freezing and sunny, and replace it each night prior to sunset. Whatever cloth you use, make sure the cloth goes all the way to the ground to capture radiant heat from the ground. If there is mulch around the plant, rake away during the day, if above freezing and sunny, to allow the soil to warm up.
Roses
Some roses are more sensitive to cold than others. As a group, hybrid tea roses are the most vulnerable. Make sure they are watered prior to predicted freezing temperatures, protect the root zone with mulch on the soil mound. You may also wish to cover your sensitive roses with frost cloths.
Container Plants
What do do if frost damages your plants? Wait!
Frost damage occurs when the water inside the cells of a plant freeze, causing damage to the cellular walls, which harms the overall health of the plant. Frost damaged vegetation will wilt, turning brown or black, as if they have been scorched. The bark may crack, or split. In severe or prolonged periods of frost the plant can die.
If you see what appears to be frost damage, wait until late spring until all chance of frost has passed. Plants are resilient and can often recover on its own, producing new growth. Pruning what seems to be damaged branches too soon can cause significantly more trauma, even death, to a vulnerable plant that might otherwise have recovered in the spring.
Resources
- https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=22929
- https://sacmg.ucanr.edu/Frost_Protection/
- https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=45517
- http://ipm.ucanr.edu/PMG/GARDEN/ENVIRON/frostdamage.html
Denise Godbout-Avant has been a UC Cooperative Extension Master Gardener in Stanislaus County since 2020.
Did you know? All cacti are succulents, but not all succulents are cacti?
This class will focus on the non-spiny succulent plants that can be grown in our area, especially those that use less water - and there are a lot to choose from! During class you'll learn the names of common succulent plants, their sun and water requirements, and how to care for them. Classes last approximately 90 minutes.
Stanislaus County Libraries – Gardening with Succulents Classes
Tuesday, October 4, 2022 at 6:00 p.m. – Salida Library
Saturday, October 15, 2022 at 2:00 p.m. – Riverbank Library
Monday, October 10, 2022 at 6:00 p.m. – Ceres Library
Tuesday, October 18, 2022 at 6:00 p.m. – Oakdale Library
Monday, October 24, 2022 at 6:15 p.m. – Modesto Library
Wednesday, October 26, 2022 at 6:00 p.m. – Turlock Library
Stanislaus County Agricultural Center, Harvest Hall, Gardening with Succulents Workshop
Cost: $25
Space is limited, register now at https://ucanr.edu/succulent/workshop/2022
Turlock Community Gardens – Drip Irrigation
Saturday, October 15, 2022 from 9:00-10:30 a.m.
Want to know more about how drip irrigation works? Come learn from our Master Gardener who will give you an overview. Bring your questions!
Patterson Library – Composting Basics
Wednesday, October 12, 2022 at 2:30 p.m.
If you missed our composting classes held at other libraries, you still have a chance to take this one! Learn the basics of composting, including the difference between “greens” and “browns,” what you can and can't compost, and simple tricks for being successful. Plus, one lucky person will take home a free compost bin!
*no need to register for Stanislaus County Library or Turlock Community Garden Classes. Just come. We look forward to meeting you!
