- Author: Janet Hartin
Benefits of Plants to People, Communities and Urban Ecosystems: Part 1:
The link between horticulture and health and well-being and to urban ecosystems has been scientifically documented for centuries. In 1812, psychiatrist, professor, and Declaration of Independence signer Dr. Benjamin Rush reported in his book “Medical Inquiries and Observations, Upon the Diseases of the Mind” (Rush 1812) that patients “digging in the dirt”
Benefits related to cognitive functioning, societal and community health, and mental health are summarized below. Ecosystem and physical health benefits from interacting with nature will be discussed in next month's blog.
Improved Cognitive Functioning
Several studies link participation in gardening activities to enhanced cognitive functioning (Bratman et al. 2012; Dadvand et al. 2015; Kuo et al. 2021; Ohly et al. 2016; Park et al. 2019; Stevenson et al. 2018; Wells 2000. Research conducted by Kuo and Sullivan (2001) and Mayer et al. (2009) found that exposure to nature in urban settings can enhance attention span, working memory, and concentration. Both youth and adults who participate in greening and gardening projects were also found to have higher cognitive functioning in the areas of short and long term memory, focus and concentration (Dadvand et al. 2015; Markevych et al. 2019; Matsuoka 2010; Meuwese et al. 2021; Park et al. 2019; Stevenson et al. 2018) and reduced symptoms of ADHD (Faber Taylor and Kuo (2011).
Other studies summarized in a literature review (Williams and Dixon 2013) found that kindergarten and middle school students who participated in school gardening activities linked to classroom learning in biology, nutrition, mathematics, and other subjects earned higher grades and attained greater academic achievement than non-participants. A recent study linked high tree canopy coverage on school grounds with higher achievement scores in math and reading in middle school students across a wide range of socioeconomic and ethnic backgrounds (Kuo et al. 2021). The experiential (hands-on) learning elements of school gardens can also bridge the gap between traditional and non-traditional learners due to its multi-sensory nature (Kolb and Kolb 2005). School gardens play an especially important academic role among elementary-aged youth from low-wealth inner city communities exposed to outdoor experiential learning that was previously lacking (Dyg et al. 2020; Kuo et al. 2021; Ray et al. 2016; Williams et al. 2013). However, Hoover et al. (2021) found that successful, sustainable school gardens require strong administrative and district support in addition to enthusiasm and support from parents and teachers.
Enhancement of Societal and Community Health
Urban greening projects that remediate vacant land, landscape streets and neighborhoods, create community gardens, and improve the health of wetlands and undeveloped natural environments can build community cohesiveness, neighborhood bonding, and mutual community pride (Diamant and Waterhouse 2010; Draper 2010; Glover et al. 2005; Hartwig and Mason 2016; Kuo and Sullivan 2001; Moyer et al. 2019; Neo and Chua 2017; Saldivar-Tanaka and Krasny 2004). With blighted uncared-for vacant lots comprising nearly 15% of total land area of U.S. cities (Branas et al. 2018) these opportunities are substantial. Results also indicate that gardening and urban greening projects unite people from different cultural and ethnic backgrounds who enjoy growing and sharing produce from their native regions (Agustina and Beilin 2012; Baker 2004; Cruz-Piedrahita et al. 2020; Dyg et al. 2016; Hartwig and Mason 2016; Teig 2009). Building a sense of community through social engagement, celebrations, and communal meals has also been found to benefit both gardeners and non-gardener participants (Ober et al. 2008).
Well-designed and maintained urban green spaces not only bring people together, but can reduce crime, gun violence and enhance the safety and cohesiveness of urban neighborhoods, as summarized in several literature reviews (Bogar and Byer 2016: Mancus and Campbell 2018; Shepley et al. 2019). Some of the strongest links reported in the literature involve crime reduction in vegetated and well maintained urban neighborhoods and walkways (Branas et al. 2018; Demotto 2006; Garvin et al. 2013; Locke et al. 2017) and a reduction in gun violence in neighborhoods with green spaces including trees (Branas et al. 2018; Kondo 2017; Schertz et al. 2021; Wolfe et al. 2012). One study found that community-based greening projects that vegetated vacant lots was an effective strategy to improve neighborhood safety, resulting in a nearly 40% decrease in violent crime (Heinze et al. 2018). It should be noted that other researchers (Groff and McCord 2012) found a higher incidence of opportunistic crime in high tree canopy covered areas, perhaps due to concealed illegal activities. Another study found that actively participating in community greening projects from design through implementation and maintenance can result in a sense of accomplishment and satisfaction (Murphy-Dunning 2009). Neighbors caring for urban green spaces together also tend to spend more time conversing and building important social relationships than do non-participants (Peters et al. 2010).
Improved Mental Health
Multiple literature reviews link interactions with nature to improved mental health in both youth and adults (Bowler et al. 2010; Clatworthy et al. 2013; Coventry et al. 2021; Cruz-Piedrahita et. al. 2020; De Vries et al. 2003; Tillmann et al. 2018) in studies conducted in parks, gardens, urban green spaces, and even shopping malls. The restorative impact of simply viewing plants has also been widely studied. Walking through a park and even viewing a natural scene through a window can lead to a sense of well-being, restfulness, reflection, and reduced mental fatigue (Shanahan et al. 2019). More recently, Dzhambov et al. (2020) found lower rates of depression in students homebound for long periods of time during the COVID-19 pandemic with views of plants (indoors and out) compared to students who lacked plant interactions. Bowler's (2010) literature review also highlighted strong associations for self-reported positive emotions and lower levels of anger and sadness in natural settings compared to non-natural settings. Interactions with nature can also reduce symptoms of depression and anxiety (Beyer et al. 2014; Gonzalez et al. 2010; Lee and Maheswaran 2011; Van den Berg and Custers 2011; Wilson and Christensen (2011).
Thompson Coon et al. (2011) reported that exercising outdoors in natural settings led to greater feelings of positivity and revitalization, less tension, anger, and depression compared to the same amount of exercise indoors. Other studies link gardening to feelings of peace and contentment (Meuwese et al. 2021; Shanahan et al. 2015; Shanahan et al. 2019). MacKerron and Mourato (2013) reported that individuals who interact with nature are often happier than those lacking this interaction and Ambrose et al. (2020) reported that home gardeners growing food crops experienced particularly high levels of happiness and meaningfulness. Bakolis et al. (2018) linked two elements of mental well-being (optimism and energy) to interactions with nature while Van den Berg and Clusters (2011) and Wood et al. (2016) found a link between engagement with nature and a reduction in stress. While White et al. (2019) determined that these benefits are maximized when individuals spend 120 minutes a week or more interacting with nature, shorter periods of exposure are also beneficial (Shanahan et al. 2016; Shanahan et al. 2019; White et al. 2019).
Other studies reported a link between growing food and a deepened sense of purpose (Tzoulas 2007; Wiesinger 2006). Digging in the soil can be a welcome distraction from busy lives laden with deadlines, traffic jams, and other everyday stressors. Focusing on the needs of plants, whether it be watering, fertilizing, harvesting or other tasks, can prove pleasantly distracting, providing time for reflection and even problem resolution (Capaldi et al. 2015; Meuwese et al. 2021; Stevenson et al. 2018). Several research papers report important positive roles that plants play related to mental health as impacts of climate change increase (Cryder et al. 2006; Dillman-Hasso et al. 2021; Doherty 2018; Fernandez et al. 2015) related to posttraumatic stress disorder (PTSD), major depressive disorder, stress, anxiety and others.
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- 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
What do more than a dozen community and school garden organizers, members and directors of 15 non-profit boards, several K-12 teachers, a department chair from Loma Linda University a, retired USDA senior marketing manager, a sociologist, an anthropologist, a handful of IT and human resource managers, a structural engineer with a second career as a public health educator and 40 other San Bernardino County residents have in common? They all have a desire to give back to their communities and were recently accepted into our UC Cooperative Extension San Bernardino County Master Gardener program.
The Master Gardener 'class of 2021' hails from all parts of the county including Yucca Valley, Victorville, 29 Palms, Running Springs, San Bernardino, Redlands, Chino, Montclair, Chino Hills, Running Springs, Pinion Pines, Colton, Rancho Cucamonga, Rialto, and Ontario. They will be brought together for the first time ever in the history of the program entirely via Zoom! In exchange for the horticulture knowledge they receive during the 18-week training class, each has agreed to volunteer 50 or more hours helping county residents landscape more sustainably and grow fruits and vegetables in home, community, and school gardens.
Please help Master Gardener Coordinator Maggie O'Neill, our 150+ current Master Gardeners, and me welcome these new students into our program. I am excited to get to know them and inspired already by their passion and giving spirit. Besides helping residents landscape more sustainably, this year the Master Gardener program will focus heavily on helping county residents develop home, school, and community gardens. This closely aligns with the increased interest county residents have in growing food and adopting healthier lifestyles. Master Gardeners are in the process of developing vegetable planting guides for our three main climate zones (valley, high desert and mountains), ‘how to' videos on planting, growing, and harvesting cool and warm season vegetables, and conducting workshops (via zoom for the time being) to help current and new home, community and school gardeners become even more successful. And, of course, Master Gardeners will continue to staff our email and telephone helplines and hope to resume staffing their Farmers' Markets booths as soon as it is safe to do so!
I'm looking forward to another great year!



- Author: Janet Hartin
Watch out for these insects! Invasive shot hole borers (ISHB) represent two related species of beetles (polyphagous and Kuroshio) in the genus Euwallacea. Both spread fusarium dieback, a disease that restricts the flow of water and nutrients in the tree, resulting in dead branches, dropped limbs, and even death. Over 60 species of native and non-native ornamental trees and avocados in Southern California are susceptible the ISHB/fusarium dieback complex.Examples of known hosts of the ISHB/fusarium dieback complex include: Box Elder (Acer negundo), Avocado (Persea americana), English Oak (Quercus robur), Valley Oak (Quercus lobata), California coast live oak (Quercus agrifolia), Big leaf maple (Acer macrophyhllum) silk tree (Albizia julibrissin) Liquidambar (Liquidambar styraciflua), Coral tree (Erythrina coralladendron), California sycamore (Platanus racemose), Blue Palo Verde (Cercidium floridum), Purple orchid tree (Bauhinia variegate), Kurrajong (Brachychiton populneus); and many species of Acacia.
The beetles are native to Southeast Asia and were likely introduced into California in shipped goods, wood products, or packaging. While tiny (about the size of a sesame seed), they are prolific, tunneling into host trees and living and reproducing in galleries while feasting on the disease-causing fungus they spread from tree to tree. Females are black and much more common than the small wingless brown males, which are rarely found.
While the initial infestation occurred in Los Angeles County in 2003, beetles travel about 12 miles a year and have now spread fusarium dieback into Orange, San Diego, Riverside, San Bernardino, Ventura, and Santa Barbara Counties. Orange County alone has spent millions of dollars removing infested trees and managing the spread of the ISHB/fusarium dieback complex.
Identifying ISHB in a timely way is essential to reduce damage and slow its spread. Look for round borer entry holes about the size of the tip of a medium ballpoint pen. Staining, gumming, discoloration of wood beneath the bark, and/or frass (sawdust-like material) are other common signs and symptoms. There may also be white powdery exudate around beetle entry holes. Keep in mind that there are many other disorders that have similar symptoms. For example, other fungal diseases produce exudate and staining and other types of borers leave entry holes of various shapes and sizes.
To date, no effective control measures have been found once trees are infested, although entomologists and plant pathologists from the University of California, The USDA Forest Service and other agencies continue to research viable integrated pest management options including biological control.
To prevent and/or reduce spread of ISHB/fusarium dieback:
- Bring only ISHB-free greenwaste (used for mulch and soil amendments) and firewood onsite. Both products can harbor ISHB which can persist for months.
- Treat infected wood onsite whenever possible. Wrap or completely cover wood that cannot be immediately treated and wood that is moved offsite for treatment elsewhere.
- Chipping infested wood to 1 inch or less can kill 95% of the beetles, while solarizing it using a clear tarp eliminates both ISHB and spores produced by the fungus. Logs can also be solarized. Composting is another option that, when done correctly, can kill both beetles and fungal spores.
- Untreated logs, branches, or woodchips infested with ISHB should not be used for firewood or mulch.
- Remove stumps as well as dead trees.
- Follow International Society of Arboriculture pruning standards and never top or flush cut trees which leave open wounds.
- Spray a 70% ethanol solution on equipment and tools since fusarium fungi can adhere to both.
- Keep trees healthy (water mature trees deeply and infrequently, avoid over or under-fertilization, etc.).
- Monitor susceptible tree species often to identify damage as early as possible. Useful detection and reporting tools and more detailed information on the ISHB/fusarium dieback complex can be found here: ucanr.edu/sites/pshb
For more detailed information on the ISHB/fusarium dieback complex, please visit these websites: https://ucanr.edu/sites/pshb/ https://www2.ipm.ucanr.edu/agriculture/avocado/polyphagous-shot-hole-borer-and-kuroshio-shot-hole-borer/ https://cisr.ucr.edu/invasive-species/polyphagous-shot-hole-borer https://californiareleaf.org/pests/