- Author: Janet S Hartin
To date, over 2,000 climate-ready shade trees and tips on their planting and long-term care have been provided by UC Master Gardeners and over 20 partners to residents of low shade neighborhoods in San Bernardino and Riverside Counties through the “Trees for Tomorrow Start Today” project. Tree species given away are identified from research projects including the joint University of California/United States Forest Service (USFS) study at UC Riverside as well as from other research, local observations, and input from the green industry and academic colleagues.
Why is this project so important? 95% of Californians now reside in cities and suburban environments. Resulting urban heat islands created by built environments coupled with impacts of climate change can be mitigated through nature-based solutions. Planting climate-ready shade trees now will help ensure cooler urban areas in the next several decades as trees mature and maximize their urban ecosystem benefits. Fortunately, the shade from a single well-placed tree can decrease surface temperatures of black asphalt and artificial turf by more than 70 degrees F in hot inland and desert cities. Studies show that surrounding air temperatures can also be reduced through the transpiration process.
A major goal of the"Trees for Tomorrow Start Today" project is to enhance tree canopy cover in low shade neighborhoods also plagued with much higher than average levels of air pollution and pulmonary and cardiovascular disease incidence. Events over the past month have occurred in Fontana, San Bernardino, and the Salton Sea.
Thank you to all our partners and, especially, our tree recipients, for greening and cooling your yard and neighborhood!
- Author: Janet Hartin
1. Select drought-resistant plants that grow well in your climate zone and microclimate (sun, shade, etc.). Try these search engines:
SelecTree: A Tree Selection Guide (calpoly.edu) Plant Search Database
Plant Search Database - Water Use Classification of Landscape Species (WUCOLS IV) (ucanr.edu)
For inland San Bernardino County: Home - Inland Valley Garden Planner
2. ‘Hydrozone': Place plants with similar water needs (very low, low, medium, high) together and water the hydrozones on different valves (or, if hand watering, water plants requiring the most water longer but not necessarily more often than other plants).
3. Make sure your irrigation system is operating properly (pressure, spacing, no weeds around heads, no broken parts, etc.).
4. Irrigate based on species and seasonal water needs (highest in summer) and soil type (sandy loam, clay loam, etc.).
5. Irrigate slightly below the current root zone depth of your plants to encourage deep rooting into cooler soil: - 6”-8” for annuals, perennials, and turf - 8”- 1' for shrubs - 1' or deeper for trees
6. Water early in the morning when soil evaporation is minimal.
7. Control weeds. They compete with your garden plants for water.
8. Spread and maintain 2-4” of mulch around garden plants and trees (3-4” for wood chips, 2” for pebbles, decomposed gravel, etc.) keeping it a few inches away from tree trunks.
9. Avoid over-fertilizing. Too much nitrogen creates weak growth and the need for more water.
10. If you have a lawn and still want to keep it, water based on the UC ANR 'Lawn Watering Guide': http://ucanr.org/freepubs/docs/8044.pdf
Contact a trained University of California Cooperative Extension (UCCE) Master Gardener in San Bernardino County for more help! mgsanbern@ucanr.edu (fastest!) or: (909)387-2182 (leave a message for a return phone call)
Redlands trees
- Author: Janet Hartin
Many previously “welcomed” urban tree species have outlived their stay, becoming invasive and crowding out other plants in our Southern California landscapes. You can help by avoiding planting these trees identified by various sources (including the California Invasive Plant Council) to be too aggressive and habitat/resource-depleting for further planting.
Invasive Trees to Avoid Planting
Athel (Tamarix aphylla)
Black Locust (Robinia pseudoacacia)
Blackwood Acacia (Acacia melanoxylon)
Brazilian Pepper (Schinus terebinthifolius)
Chinaberry (Melia azedarach)
Chinese Tallow Tree (Triadica sebifera)
English Hawthorn (Crataegus monogyna)
Peruvian Pepper Tree (Schinus molle)
Red Gum (Eucalyptus camaldulensis)
Russian Olive (Elaeagnus angustifolia)
Saltcedar (Tamarix ramosissima, T. gallica, T. chinensis)
Silver Wattle (Acacia dealbata)
Smallflower Tamarisk (Tamarix parviflora)
Tasmanian Bluegum (Eucalyptus globulus)
Plant These Instead
They are drought/heat resistant, low maintenance, and have no known significant pest or disease problems and are not currently overplanted). Find other suggestions here: https://www.cal-ipc.org/solutions/prevention/landscaping/dpp/?region=socal
African Fern Pine (Afrocarpus falcatus) (formerly Podocarpus elatior)
Cascolote (Caesalpinia cacalaco Smoothie®)
Desert Willow ‘Bubba' (Chilopsis linearis)
Fringe Tree (Chionanthus virginicus)
Island Oak (Quercus tomentella)
‘Maverick' Mesquite (Prosopis glandulosa)
Mulga (Acacia aneura)
Netleaf Hackberry (Celtis reticulata)
Pink Chitalpa (x Chitalpa tashkentensis 'Pink Dawn')
‘Red Push' Pistache (Pistacia x ‘Red Push')
Thornless South American Mesquite (Prosopis x Phoenix)
/span>- Author: Janet Hartin
“To forget how to dig the earth and to tend the soil is to forget ourselves.” Mohandas K. Gandhi, World leader, political ethicist, lawyer
“Everything that slows us down and forces patience, everything that sets us back into the slow circles of nature, is a help. Gardening is an instrument of grace. ” May Sarton, Poet “
"May our heart's garden of awakening bloom with hundreds of flowers.” Thich Nhat Hanh, global spiritual leader and activist “If you have a garden and a library, you have everything you need.” Marcus Tullius Cicero, Roman philosopher
"The importance of encouraging our children in outdoor work with living plants is now recognized. It benefits the health, broadens the education, and gives a valuable training in industry and thrift. The great garden movement is sweeping over all America, and our present problem is to direct it and make it most profitable to the children in our schools and homes. — Van Evrie Kilpatrick, 1918, in “The Child's Food Garden”
As the above quotes so beautifully proclaim, interacting with nature, whether passively (viewing plants) or actively (gardening, etc.) offers many positive benefits. In fact, the link between horticulture and health and well-being has been scientifically documented for centuries. In 1812, psychiatrist, professor, and Declaration of Independence signer Dr. Benjamin Rush reported that patients participating in gardening activities had better mental health outcomes than non-gardening counterparts.
Many additional papers were published throughout the 1800's documenting benefits of active participation in gardening. More recently, positive links between simply viewing plants through a window or even on a television, movie, or exercise apparatus screen have been reported in peer-review journals. A groundbreaking study in this area was published in 1984 by environmental psychologist Robert Ulrich (Ulrich, 1984) who compared post-operative patients recovering from gall bladder surgery who had views of landscape plants to recovering patients who had the same surgery in the same facility with views of a brick wall. Patients with landscape views had fewer surgical complications, shorter hospital stays, required fewer analgesics, had better moods, and even fewer derogatory remarks by medical staff in their daily records.
Since 1984, dozens of other studies have documented similar positive outcomes resulting from both passive and active engagement with nature and plants. These include improved physical, mental and emotional health; environmental benefits; and community and societal benefits. Recent literature reviews that summarize these findings include:
- An overview of 77 peer-reviewed journal articles (Howarth, et. al., 2020) identified 35 positive outcomes linking physical and mental health and well-being to active and passive horticultural interactions. doi: https://10.1136/bmjopen-2020-036923
-A meta-analysis (Soga, 2016) of 22 studies identified several positive mental health outcomes related to gardening including mood, group cohesiveness, cooperation, pride, well-being, and more. https://doi.org/10.1016/j.pmedr.2016.11.007 -
An overview of 45 peer-review studies (Shepley, et. al., 2019) identified links between properly designed and maintained urban green spaces and crime, gun violence, and the overall safety and cohesiveness of low-wealth urban neighborhoods. https://doi.org/10.3390/ijerph16245119
- A review of 120 papers (Crus-Piedrahita, et. al., 2020) reported public health benefits from urban horticulture activities in the global North. Thirty-two papers had a specific focus on social cohesion and/or social capital. https://doi:10.1016/j.glt.2020.10.001
-Alizadeh (2019) synthesized research regarding the environmental benefits of urban plants, highlighting their vital roles in combating climate change, cooling urban heat islands, providing habitat, removing air and water pollutants, enhancing soil health, and more. https://www.researchgate.net/deref/https%3A%2F%2Fdoi.org%2F10.1108%2FIJCCSM-10-2017-0179
Enjoy your garden! Enjoy a day in nature.
- Author: Janet Hartin
an plants help cool our urban heat islands and mitigate impacts of climate change in our inland cities? I've been interested in measuring the temperatures of living and non-living surfaces for some time. Preliminary results are in! Use of dark asphalt, synthetic turf,
What can you do?
Take care of your trees, shrubs, groundcovers, and lawns to maximize their ability to cool the surrounding environment. In the same experiment described above, the coolest temperatures occurred in lawns growing in the shade of a mature tree. This is due to living plants cooling the environment during the process of transpiration. Non-living surfaces don't provide this natural air-conditioning. While many people believe lawns waste water, it's important to fully consider the alternative of replacing a water-efficient warm-season lawn like Bermuda or Buffalograss with either dark mulch or no living plants at all. The lawns are much cooler! Our previous UC studies determined that it's often not the lawns (and other sprinkler-irrigated plants like groundcovers) that waste the water, it's the uneven coverage (low distribution uniformity) of most sprinkler systems, coupled with not applying the right amount of water seasonally.
However, If you're tired of your high maintenance lawn and want to ditch your lawnmower, fertilizers, and pesticides, consider a low-maintenance drought-resistant groundcover that has similar cooling effects without the need for chemical inputs.
Plant drought-tolerant groundcovers
Here are just a few examples:
Peruvian Verbena (Verbena peruviana). This groundcover grows to only 1" tall and sports dark green leaves and white to pinkish (several hybrids available) blossoms that bloom from spring through fall. It spreads quickly and requires little water once established.
Dwarf Rosemary (Rosmarinus prostratus) This particular rosemary species is a low-growing groundcover. It is a great choice for rock gardens, reaching only 6 inches tall. It produces purple flowers in the summer and attracts pollinators and can be used for culinary purposes (bottom).
Gold Dalea (Dalea capitata). This semi-deciduous evergreen grows between 8" to 1' tall and has small yellow flowers that bloom in spring and fall and a pleasant scent. It is very heat tolerant and great for urban heat islands (parking lots, etc.) as well as planters and paths (lower right).
For more information on trees, groundcovers, shrubs, and vines suitable for your own home, contact a UC Cooperative Extension Master Gardener volunteer in your county using this link: https://mg.ucanr.edu/FindUs/