- 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
It's only right that our University of California Cooperative Extension (UCCE) San Bernardino County Master Gardener ‘Trees for Tomorrow' team of volunteers are our featured ‘Spotlight' Master Gardeners for September, 2021. They provided vital education to Redlands residents receiving gratis trees through a multi-partnership grant obtained by Inland Empire Resource Conservation District Manager Mandy Parkes. 
It's an honor and privilege to recognize UCCE San Bernardino County Master Gardener Project Leader Debbie LeDoux and her dedicated team of 'Trees for Tomorrow' volunteers: Zhibo (Sandy) Anderson; Consuelo (Connie) Davis (pictured); Pam O'Connell; Gail Sefl; and Husam Yousef. These dedicated Master Gardeners were tasked with helping residents select, plant and care for drought, heat, and pest tolerant trees. (Species including Chilopsis linearis 'Bubba', and Pistacia x 'Red Push' were selected due to their excellent performance in our University of California/United States Forest Service research project as 'climate-ready' trees able to withstand harsh conditions related to our changing climate.) Working with a team of California Climate Action Corps volunteers, civic leaders, Common Vision Coalition, and other groups, nearly 100 trees were planted in yards and parks lacking the preferred 25% tree canopy cover.
Trees can cool urban heat islands by 50 degrees Fahrenheit or more during spring and summer, creating welcome oases in hot inland communities. With spring 2021 temperatures so high they broke previous records on multiple dates, the project is especially timely and necessary.
In addition to proper tree selection, trees require the right long-term care. Master Gardeners will continue to provide advice on irrigation, pruning, fertilizing and pest control to residents receiving trees long after the trees are planted. This is critical since an average urban tree lives less than 20% of its potential lifespan due largely to poor care. The long-term engagement of Master Gardeners with residents is as important as is selecting the right species.
UCCE Master Gardeners are all volunteers, giving of their time and talents to enhance the quality of life for individuals and families who call San Bernardino County their home. Each Master Gardener is required to complete a rigorous 18-week training class complete with exams, class projects, and lots of participation! Due to COVID-19, volunteers had to master key horticultural concepts during the first ever all on-line training class. Only recently have they been able to meet fellow Master Gardener graduates and, in some cases, the Redlands residents they mentored through the tree canopy enhancement project. They truly exemplify community spirit and all it takes to successfully work together under adverse conditions. Kudos to each and every one of you from Master Gardener Coordinator Maggie O'Neil and myself! You are creating a cooler, greener and healthier environment for our children's children.
I asked the honored Master Gardeners their thoughts on the project. Here's what they had to say:
“The Redlands tree canopy project was the best volunteer project ever. In the midst of Covid-19, horrific politics and way too many good byes, it was a truly joyous experience. The legacy of being a part of the group that promoted healthy sustainable trees, knowledge of how to plant and care for them, tips on maintaining their health and beauty was the absolute best. For me as a Master Gardener, it was so much fun. I loved the site walks and getting to help our participants select the perfect sustainable trees for their properties. What started as a one-on-one visit often expanded to an enlarged group of neighbors and extended family. I got to give out many handouts and publications and promote our excellent Master Gardener program. I got to share our helpline email and phone numbers. I love the fact that I have been asked to revisit sites to see how great they are doing (once to make sure the tree did not look funny!). I receive emails every now and then asking me questions and showing me pictures of "Our Trees.” So much fun, Janet. Thank you. By far the coolest project ever! Pam O'Connell
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There are a few things that really made an impact on me.1) It was rewarding to attend the Zoom presentation you developed that provided education to various professionals on the importance of planting sustainable trees. I found it to be open and inclusive allowing for good interchange of ideas and concerns.2) There are many beautiful trees that are sustainable.3) Reaching out to the community to offer beautiful, sustainable trees was a worthwhile way to show how various organizations can work together to benefit the community while trying to improve our environment.4) When dealing with homeowners that belong to an HOA, additional time and communication may be needed to assist them in obtaining approval for trees from their HOA's. Connie Davis
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"I see tree planting efforts similar to what a trend of the future is to combat climate change and increase awareness of the importance of trees and tree canopies in our neighborhoods. Not only that but I see this project expanded to other cities in the county of San Bernardino. The continuity of this project is so valuable so that we can see the positive impact on the environment and the well-being of San Bernardino residents in the coming decades. I see this important work being organized and well-coordinated by involving the appropriate stakeholders at all stages of the planning project. It is about time to give back what we have taken for tens of years!" Husam Yousef 
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It was rewarding to see local homeowners excited about planting trees and grateful for the program providing them. Gail Sefl
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THANK YOU ALL! Janet Hartin and Maggie O'Neill
- 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/
- Author: Janet Hartin
In your landscape, your trees and edibles should come first under drought and water restrictions! If there just isn't enough water to go around, your lawn and flowers should be sacrificed instead. Trees are our most valuable landscape resource and take years to maximize their benefits (shade, cooling, habitat/ecosystem enhancement, carbon dioxide storage, energy conservation, pollution filters, etc.). 
Just a few slow, deep waterings with a garden hose away from the trunk and slightly beyond the drip line will keep established trees alive, even during summer. Remember to keep trunks dry!
Here are some other tips:
• 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. (Note: dark colored dyed mulches should be avoided in inland and desert areas due to their high surface temperatures that can > 60 degrees F hotter than living plants and lighter colored mulches.)
• Water early in the morning when soil evaporation is minimal.
• Control weeds. They compete with other plants for water.
• Avoid fertilizing. Nitrogen increases growth and the need for more water.
• Don't plant new plants during the summer when temperatures are highest. Even drought-resistant native and non-native plants need regular watering their first season.
