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An Update of the Literature Supporting the Well-Being Benefits of Plants: A Review of the Emotional and Mental Health Benefits of Plants



Consumers have historically shown an inclination to purchase plants that enhance their quality of life, meaning they will purchase items that positively influence their social, physical, psychological, cognitive, environmental, and spiritual well-being. Plants in native and improved landscapes (and interiorscapes) have been documented to influence each of six quality of life constructs. This paper summarizes publications regarding the emotional and mental health benefits associated with plants, addressing reduced anxiety and stress, attention deficit recovery, fractals and visual response, decreased depression, enhanced memory retention, greater happiness and life satisfaction, mitigation of post-traumatic stress disorder (PTSD), increased creativity, enhanced productivity and attention, reduced effects of dementia, and improved self-esteem. This research should be strategically incorporated into both industry-wide and firm-specific marketing messages that highlight the quality of life value proposition in order to maintain the industry's sense of value and relevance to consumers of the future. Index words: benefits of plants, emotional health, mental health.
An Update of the Literature Supporting the Well-Being
Bene¢ts of Plants: A Review of the Emotional and Mental
Health Bene¢ts of Plants
Charles Hall and Melinda Knuth
Consumers have historically shown an inclination to purchase plants that enhance their quality of life, meaning they will purchase
items that positively influence their social, physical, psychological, cognitive, environmental, and spiritual well-being. Plants in
native and improved landscapes (and interiorscapes) have been documented to influence each of six quality of life constructs. This
paper summarizes publications regarding the emotional and mental health benefits associated with plants, addressing reduced anxiety
and stress, attention deficit recovery, fractals and visual response, decreased depression, enhanced memory retention, greater
happiness and life satisfaction, mitigation of post-traumatic stress disorder (PTSD), increased creativity, enhanced productivity and
attention, reduced effects of dementia, and improved self-esteem. This research should be strategically incorporated into both
industry-wide and firm-specific marketing messages that highlight the quality of life value proposition in order to maintain the
industry’s sense of value and relevance to consumers of the future.
Index words: benefits of plants, emotional health, mental health.
Significance to the Horticulture Industry
This paper is the first of a four-part series that provides a
review of the substantial body of peer-reviewed research
that has been conducted regarding the economic, environ-
mental, and health and well-being benefits of green
industry products and services. This article focuses
specifically on the health and well-being benefits. This
research should be strategically incorporated into both
industry-wide and firm-specific marketing messages that
highlight these quality of life dimensions in order to
enhance the perceived value and relevance of green
industry products for gardening and landscaping consumers
in the future.
In 2011, Hall and Dickson published a forum article in
the Journal of Environmental Horticulture (JEH) that
summarized the economic, environmental, and health and
well-being benefits associated with people-plant interac-
tions. The proposition put forth in that article was that
green industry firms needed to focus on these types of
functional benefits in their marketing messages to con-
sumers rather than simply base their value proposition on
the features and benefits of the plants themselves (e.g.
aesthetic aspects, disease resistance, cold/heat tolerance,
salt tolerance, etc.). By doing so, the end consumer would
see the inherent ways in which plants improve the quality
of their lives and begin perceiving plants to be a necessity
in their lives rather than a mere luxury they could cast aside
during economic downturns, as they did during the ‘‘Great
Recession’’ of 2008-2009.
Since 2011, there has been a plethora of additional
research conducted regarding these functional plant
benefits and these voluminous studies provide compelling
evidence that warrants further attention. Thus, this new
series of forum articles attempts to update the findings
summarized in the original article by Hall and Dickson by
presenting a summary of the research on plant benefits that
has been conducted since 2011. By doing so, this new
information provides the basis for future innovative green
industry marketing efforts, which may, in turn, positively
influence the elasticity of demand for plants in general.
The first topic in the four-part series, Emotional and
Mental Health Benefits of Plants, is one that has been
shown to resonate with consumers of all demographic
segments (Hall and Dickson, 2011). These benefits are
segmented and discussed using the following categories:
anxiety and stress reduction, attention deficit recovery,
fractals and visual responses, decreased depression,
enhanced memory retention, greater happiness and life
satisfaction, mitigation of PTSD, increased creativity,
enhanced productivity and attention, reduced effects of
dementia, and improved self-esteem.
Reduced anxiety and stress
Significant correlations have been found between the use
of open spaces and reduced stress. Time spent in natural
settings can help reduce mental fatigue recovery time and
improve concentration levels (Entrix 2010, Keniger et al.
2013, Kjellgren and Buhrkall 2010, White et al. 2017, Wolf
and Housley 2014). Increased access to green spaces also
reduces psychological distress, depression symptoms,
clinical anxiety, and mood disorders in adults (Astell-Burt
et al. 2013, Beyer et al. 2014, Brown et al. 2013, de Vries
et al. 2013, Fan et al. 2011, Nutsford et al. 2013, Stigsdotter
2015, Triguero-Mas et al. 2015, White et al. 2013).
The term ‘‘stress recovery theory’’ was coined by van
den Berg and Custers (2011) and includes the benefits
derived when individuals immerse in nature, including
Received for publication January 17, 2019; in revised form April 8,
Professor and Graduate Student, respectively, Texas A&M University,
College Station, Texas 77843-2133. Corresponding author: Charles
30 Copyright 2019 Horticultural Research Institute J. Environ. Hort. 37(1):30–38. March 2019
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decreased anxiety, lower heart rates, skin conductance
recovery, lower concentrates of cortisol, and positive
changes in nerve activity (Alvarsson et al. 2010, Bowler
et al. 2010, Park et al. 2010, Park et al. 2017, Russell et al.
2013). Controlling for socio-economic and demographic
characteristics, positive relationships between green space
and overall health and stress reduction have been reported
(de Vries et al. 2003) and the effects are transcendent to
viewing images of nature (Ryan et al. 2014). For patients in
hospitals, exposure to real plants or even posters of plants,
resulted in lower levels of experienced stress (Beukeboom
et al. 2012). Exposure to natural scenes mediates the
negative effects of stress; one can recover faster from the
decrease of cognitive performance associated with stress,
especially reflected in attention tasks. (Berto 2014).
Stress reduction and mental restoration occur when
individuals live near green areas, have a view of
vegetation, or spend time in natural settings (Abraham et
al. 2010, Carrus et al. 2015, Watts 2017, Wolf and Housley
2014). The amount of green space in the neighborhood, and
in particular access to a garden or allotment, were
significant predictors of stress (Thompson et al. 2016). In
fact, the amount of green space in residential areas is
positively related to resident overall health (Groenewegen
et al. 2012). White et al. (2013) also found that individuals
have both lower mental distress and higher well-being
when living in urban areas with more green space.
Women also seem to experience more stress than men do
when away from nature. Roe et al. (2013b) found that there
was a significant inverse relationship between green spaces
and stress levels with higher levels of green space resulting
in lower stress levels. Women were found to display higher
stress levels than men when exposed to the same amount of
(or less) green space. Coincidently, the percentage of green
space effects showed a positive outcome on women by
decreasing the mean cortisol concentration. Women who
lived more than 1 km away from green spaces reported
higher stress levels and perceived poorer health and quality
of life than those who lived near of green spaces
(Stigsdotter et al. 2010). Beil and Hanes 2013 also found
there is greater benefit from exposure to natural settings as
measured by pre-and-post changes in salivary alpha-
amylase and self-reported stress with more of a significant
reduction in females than in males.
Thompson (2012) found that those who lived in green
spaces experienced less stress and participated in more
physical activity. Thompson also found self-reported
decreases in stress, diurnal patterns of cortisol secretion,
and quantity of relative green space in the living
environment to all be positively correlated.
Another study found that when comparing a group of
elderly women who spent 15 sessions outside participating
in gardening activities versus staying inside, those who had
gone outside had improved muscle mass and hand
dexterity, and decreased waist circumference, whereas the
women who spent the same time indoors had decreased
muscle mass and agility and increased symptoms of
depression (Park et al. 2016).
Stress reduction through green environments has been
achieved in office settings as well. When employees were
exposed to roses in the workplace, they had significantly
less heart rate variability than those who weren’t exposed
to roses (Callaghan and Mallory-Hill 2016, Ikei et al. 2014,
Ikei et al. 2013, Smith and Pitt 2011). Interior plants can
lead to healthy, productive workplaces through enhanced
attention capacity, lower stress levels, and higher job
satisfaction from viewing plants (Gilchrist et al. 2015,
Hartig et al. 2014, Raanaas et al. 2011). This concept also
carries over to break areas within the workplace (Berto
Biophilia is defined as humans’ innate tendency to seek
connections with nature and other forms of life. Biophilic
design is the incorporation of biophilia into the built
environment. There is a growing body of literature
documenting the benefits of implementing plants on a
large scale to capture the positive psychophysiological and
cognitive benefits afforded by biophilia in architecture
(Ryan et al. 2014). This type of architecture can reduce
stress, enhance creativity and clarity of thought, and
improve well-being in urbanized communities (Browning
et al. 2016). This theory is also backed by Pouya (2016),
who found that if these concepts were applied more widely,
we would see more of a positive impact. The perceptual
and physiological stress responses are correlated to the
complexity of fractals in nature, art and architecture, and
the predictability of the occurrence of design flows and
patterns in nature (Bejan and Zane 2012, Salingaros 2012).
When young people, particularly students, have a view
of green spaces during school, students exhibit significantly
better performance on attention tests and stress recovery
(Li and Sullivan 2016). Kelz et al. (2015) validated Li and
Sullivan’s findings by having children play on different
types of playgrounds with varied levels of green space. The
playground with high green space significantly reduced
students’ physiological stress levels and enhanced their
psychological well-being. They also perceived the envi-
ronment as being more restorative.
Lee et al. (2014) studied forest activities of Japanese
citizens and found significant differences between the
responses of the subjects in forest settings compared with
those in urban environments in salivary cortisol concen-
tration (an index of stress response), diastolic blood
pressure, and pulse rate. Further, subjects felt more
comfortable, soothed and refreshed when viewing a forest
landscape than an urban landscape.
Mennis (2018) found urban green spaces are associated
with lower stress when subjects are away from home,
which is speculated to be due to the properties of stress
reduction and attention restoration associated with expo-
sure to natural areas, and to the influence of other family
dynamics affecting stress levels within the home. Subjects
may also seek out urban greenspaces at times of lower
stress or explicitly for purposes of stress reduction.
Tree cover is also associated with stress reduction. Jiang
et al. (2016) found a positive correlation between urban
street tree density and self-reported stress recovery. Song
(2015) also found that physiological effects of a forest
environment can differ depending on a subject’s initial
levels of stress and that subjects with high initial blood
pressure and pulse rate showed a decrease in these values
J. Environ. Hort. 37(1):30–38. March 2019 31
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after walking in a forested area, whereas those with low
initial values showed an increase. There was no physio-
logical adjustment effect observed in an urban area; thus,
these effects are specific to a forest environment.
Aspinall et al. (2015) also documents that forest-bathing
can cause stress reduction by using an EEG headset to
measure brain waves by amplitude and frequency.
Participants were asked to walk through an urban shopping
center to a 25-ha (62 acres) green space and a busy
commercial district with heavy traffic. The walk took
participants approximately 25 minutes each. When com-
paring the urban shopping center to the green space,
frustration, engagement, and arousal all decreased which is
consistent with restoration theory but meditation increased,
which was novel. When participants moved from the
greenspace to the busy commercial district, their arousal/
engagement increased, indicating that stress/fear also
Horiuchi et al. (2014) took another approach and used
real viewings of forests and non-forested areas and
compared near-infrared spectroscopy (NIRS) as well as
mood state scores, heart-rate, blood pressure, and sAMY
concentration (marker for stress). They found that the
NIRS signal, cerebral oxygenation levels, and mood state
levels were lower in forest settings than in non-forest
conditions, but blood pressure, heart rate variability, and
salivary amylase levels were similar. Interestedly, being in
the forest also caused a spike in cerebral activity.
This is reinforced by results of Im et al. (2016), who
looked at the effects of spending two hours in a forest in
Japan. To test neurological effects, they collected blood
and saliva samples and found that there was a significant
change in the level of cytokines that contributing to the
hyperactivity of the inflammatory response which is
physiological reaction of a stress response.
Joung et al. (2015) showed through NIRS that total Hb
(hemoglobin) concentration was significantly lower of
forest scenery over urban scenery. A lower concentration
of total Hb and oxy-Hb indicates that the quantity of
oxygen transmitted to the prefrontal cortex tissue is small.
In other words, the prefrontal cortex activity in a forest area
is more stabilized than in an urban area.
Vedder et al. (2015) took a different approach. They
used fMRI and asked individuals to imagine beautiful and
non-beautiful environments. Functional magnetic reso-
nance imaging (fMRI) showed significantly more cortical
activations when subjects imagined non-pleasant environ-
ments than when they imagined pleasant environments.
The results of this study show that a positive and a negative
frame of reference elicit distinct neural patterns of
environmental cognition. This means that non-beautiful
and non-pleasant environments demand more mental
processing than beautiful and pleasant environments. The
results correlate with previous propositions to explain the
experience of negative environments as characterized by
the demand on more mental resources than the experience
of positive environments. In other words, interacting with a
negative environment requires an additional investment in
emotion processing, cognitive control, and motor function.
These results support Aspinall et al. (2015), Horiuchi et al.
(2014), and Joung et al. (2015) with their claims of
reduction in delta waves (brainwaves for agitation and
excitement). Kim et al. (2010) found similar results when
looking at stress reactions using fMRI.
Students were recruited from Edinburgh University by
Roe et al. (2013a) to undergo an EEG study on natural
settings (fields, forests, and parks) versus urban sceneries
(buildings, roads, and walls). To control the effect of
people and animals, both were withheld from being
included in the pictures presented to the subjects. Subjects
were asked to rate each slide on four criteria based on how
attractive they found the scene, how likely are they to visit
the scene, how the scene made them feel from sad to happy
and also from calm to excited. The results for the ranking
questions showed that the landscape scenes were perceived
as more attractive, more inviting (willingness-to-visit), and
greater valence. Arousal was strongly correlated to the
urban scenes while interest was correlated to landscape
scenes. This confirms restorative theory, indicating a
positive psychological effect of natural scenes.
Rosenbaum used electroencephalogram (EEG) in a
replication-type study with eye-tracking. Given the lack
of neuroscience data in previous studies on consumer
responses and biophilic design in retail settings, they had
participants watch a video of a retail mall or lifestyle center
(e.g. an upscale shopping center or mixed-use commercial
development) with and without plants (biophilic and non-
biophilic). Those participants who viewed the biophilic
video were more enthused and interested and experienced a
higher state of mental relaxation than participants who
viewed the non-biophilic video. Participants who viewed
the biophilic video also reported lower levels of stress,
more attractiveness/focus, and were more emotionally
involved. This finding confirms previous results that
suggest that shoppers are becoming bored in their
excursions to enclosed malls while lifestyle centers
continue to proliferate.
Attention Deficit Recovery (Attention Restoration
Theory or ART)
Natural landscapes, such as beaches, waters, forests,
parks, and mountains, and availability of public open
spaces used for public entertainment and sports reduce
attention deficit disorders (ADD/ADHD) (Coutts and Hahn
2015, Frumkin 2013, Keniger et al. 2013). Green
restoration improved preschooler spatial working memory
(Schutte 2017) and cognitive functioning improved when
participants walked in nature (Berman et al. 2008).
Children with ADHD concentrated better after a walk in
a park than after a downtown neighborhood walk (Taylor
and Kuo 2009). Wilson (2015) showed that children who
play in greenspace for 30 minutes had increased sustained
mental ability and found greenspace to be restorative.
Taking micro-breaks to view nature can help with attention
restoration (Lee et al. 2015).
Fractals & Visual Response
We are so separated from nature that we make up for its
lack by imbuing our surroundings with those geometric
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qualities found in nature (Salingaros 2012). We try to shape
our immediate vicinity so that those qualities reproduce our
response to natural environments. From biophilia, natural
forms have inherent qualities, reducible to a mathematical
description, that induce a healing effect. Complex biophilic
environments dramatically increase brain size and perfor-
mance on intelligence tests (Salingaros 2012).
Decreased Depression
Being immersed in nature and vegetation were used as
active components in a therapeutic horticulture interven-
tion for clinical depression (Beute and de Kort 2018,
Gonzalez et al. 2010). Garden walking and reflective
journaling decreased depression scores in older adults
(McCaffrey et al. 2010). With patients who have major
depressive disorder (MDD), those who walked in nature
exhibited significant increases in memory span after the
nature walk relative to the urban walk. Green spaces also
reduced stress and pain, and increased attention perfor-
mance (McCaffrey et al. 2010). Participants also showed
increases in mood, but the mood effects did not correlate
with the memory effects, suggesting separable mechanisms
(Berman et al. 2012). Bezold (2018) put extensive numbers
to this idea, with a 6% lower incidence of high depressive
symptoms associated with greenness and found this
relationship to be stronger with highly populated areas.
Comparing household medical records and natural ameni-
ties, those residents with only 10% green space within
about half a mile had a 25% greater risk of depression and
a 30% greater risk of anxiety disorders versus those with
the highest degree of green space near the home (Wolf and
Housley 2014).
In a Korean study involving patients with moderate to
severe depression, participants were assigned to cognitive-
behavioral therapy in either a hospital setting or a forest
setting (arboretum), while a third group acted as a control
and were treated using standard outpatient care in the
community (Wolf and Housley 2014). Overall, depressive
symptoms were reduced most significantly in the forest
group, and the odds of complete remission were 20-30%
higher than typically observed from medication alone.
Moreover, the forest therapy group had more pronounced
reductions in physiological markers of stress, including
lower levels of the stress hormone cortisol and improve-
ments in heart rate variability, a marker of adequate
circulatory system response to stress. It appears that the
settings where psychotherapy is conducted can actually
become part of the therapy (Wolf and Housley 2014).
Enhanced Memory Retention
A 2012 experiment in Michigan found that people were
better able to perform a test of working memory (which
measures one’s ability to focus or concentrate) after
walking through a green arboretum, compared to those
who walked on traffic-heavy urban streets (Berman et al.
2012). Subjects who walked through the arboretum had a
20% improvement in working memory. Another study
determined that people who went for a 50-minute walk in
nature, compared to those who went for a similar length
walk in an urban environment, experienced less anxiety
and rumination, along with increased working memory
performance (Berman et al. 2012).
Being in nature and greenspace can also help improve
memory retention of patients suffering from strokes and
dementia (Detweiler and Warf 2005). In children, nature
exposure can influence cognitive development through
improved working memory and a reduction in inattentive-
ness (Dadvand et al. 2015).
Greater Happiness/Life Satisfaction
Interacting with nature, especially with the presence of
water, can increase self-esteem and mood, reduce anger,
and improve general psychological well-being with
positive effects on emotions or behavior (Barton and
Pretty 2010, Keniger et al. 2013, Mensah et al. 2016,
Windhager et al. 2011, Wolf and Housley 2014). In fact,
moving to homes with greener areas positively influences
mental health even after three years post-move (Alcock et
al. 2014). Moving to a less-green area significantly worsens
mental health within one year post-move, but returns to
pre-move mental health status thereafter (Alcock et al.
2014).This is true for public green spaces as well. City park
area quantity and accessibility is a strong predictor of
physical and community well-being (Larson et al. 2016).
Similarly, studies in Perth, Australia found that people in
neighborhoods with high-quality public open spaces had
better mental health than those with low-quality public
open space (Francis et al. 2012a). Features that made an
open space ‘‘high quality’’ included irrigated lawns,
walking paths, lighting, water features, playgrounds, and
birdlife. Mental health was assessed based on symptoms of
psychological distress such as nervousness and feelings of
hopelessness (Francis et al. 2012b). Findings were not
affected by the quantity of open space in the neighborhood,
nor by how frequently residents used the open space
(Francis et al. 2012a).
Pro-environmental behavior and subjective well-being
are positively associated. Those who are more connected to
nature and exhibit environmentally-conscious behaviors
tend to experience more positive vitality and life
satisfaction compared to those less connected to nature
(Capaldi et al. 2014).
Van Dillen (2012) determined, through meta-analysis,
that quality and quantity of green space was correlated to
good health. Greater species diversity positively affects
personal well-being (Dallimer et al. 2012) and neighbor-
hood well-being (Luck et al., 2009). Visiting protected
natural sites (e.g. state parks) improves perceptions of
psychological, emotional, and social benefits (Lemieux et
al. 2012). Results from a meta-analysis in Toronto, Canada
suggest that people who live in neighborhoods with a
higher density of trees on their streets report significantly
less cardio-metabolic conditions. Having 10 or more trees
in a city block, on average, improves personal health
perceptions in ways comparable to a $10,000 increase in
annual personal income or being 7 years younger (Kardan
et al. 2015). The study also found that having 11 more trees
in a city block, on average, decreases cardio-metabolic
conditions in ways comparable to an increase in annual
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personal income of $20,000 and moving to a neighborhood
with $20,000 higher median income or being 1.4 years
younger (Kardan et al. 2015).
Park et al. (2017) found that when subjects observed
plants, Oxy-Hb (oxyhemoglobin) concentrations in the
right prefrontal cortex were significantly lower, indicating
a physiological state of relaxation. Subjects also reported
more positive emotions (feeling more comfortable and
relaxed) when viewing foliage plants.
Mitigation of PTSD
Veterans with PTS (post-traumatic stress) treated with
Nature Adventure Rehabilitation (NAR) experienced an
improvement in emotional and social quality of life, post-
traumatic cognitive inventory, and hope and functioning
(Gelkopf et al. 2013). NAR seems to work through a
process of behavioral activation, desensitization, gradual
exposure to anxiety evoking situations, and gaining control
over symptomatology.
When victims of natural disasters, who are at a high risk
of PTSD, participated in horticulture therapy (HT)
programs, they showed an increase in regional gray matter
volume (rGMV) of the left subgenual anterior cingulate
cortex and left superior frontal gyrus compared with the
stress education (SE) group (Kotozaki et al. 2015,
Sekiguchi et al. 2015). They showed greater salivary
cortisol and alpha amylase levels, which are all signifi-
cantly reduced in individuals experiencing PTSD (Koto-
zaki 2014, Kotozaki et al. 2015, Sekiguchi et al. 2015). The
HT group also showed improvement on PTSD reactions,
post-traumatic growth, and positive states of mind
(Kotozaki et al. 2015). Post-traumatic growth refers to
the positive outcome of people who have experienced
traumatic events through recovering their quality of life.
People identified themselves with plant growth and gaining
a chance to be happy once more (Kotozaki et al. 2015).
Increased Creativity
Ling and Dale (2011) found a link between landscape
plants and creativity and considered how this may reflect
the potential for cultural diversity and thus sustainable
community development. Taking short walks in attractive
green environments can boost creativity and vitality
(Tyrvainen et al. 2014). These same areas can also be
used for ‘walking meetings’ which help boost creativity
(Oppezzo and Schwartz 2014).
Enhanced Productivity and Attention
Biophilic workplaces with views of nature and daylight
can lead to higher productivity and attention with
employees (Elzeyadi 2011, Windhager et al. 2011).
Workers in offices with poor light quality and views used
more sick leave hours and this effect contributes as much
as 6.5% to sick leave use. Moisture released into the air by
plants helps with a dry atmosphere, reducing headaches
and improving concentration. Visible greenery, both
indoors and out, reduces stress and increases the ability
to concentrate (Alker et al. 2014, van Duijin et al. 2011). In
one such concentration test, employees who had a view of
plants completed the test 19% faster than employees in a
room without a view of plants (Nieuwenhuis et al. 2014).
Offices in the Netherlands and Great Britain experienced a
15% increase in worker productivity when plants were
included in office space (Korpela et al. 2017, Nieuwenhuis
et al. 2014).
The Heschong-Mahone Group studied productivity at
the Sacramento Municipal Utility District Call Center
where employees were either seated with views of
vegetation through large windows or were excluded from
the vegetation view. Employees who had a vegetation view
made 6-7% more calls per hour than those with no view.
The initial investment of installing the windows was
recovered in 4 months by improved productivity (Alker et
al. 2014).
Jumeno and Matsumoto (2013), however, did not find
that plants in the workplace had a significant effect on
productivity or attention but found a significant difference
in the employee perceptions of friendliness, comfort,
freshness, and cleanliness of the workplace. Erzsebet et
al. (2014) suggests that improved employee productivity
and attention can be positively affected by the air-
purifying qualities of plants in the workplace by reducing
various allergies, irritations, hypersensitivity, asthma,
drowsiness, and eye problems, while also improving mood.
Jumeno and Matsumoto (2016) sought to quantify the
number of plants in a room that it would take to generate
positive results and found the more plants in a room, the
better the mood of the subjects. Their study also found that
the number and the size of plants affected the perceived air
quality and reaction times and as few as three small-to-
medium sized plants can make a positive difference. Even
a brief view of a green roof can have positive effects on
mood and productivity (Lee and Maheswaran 2011).
When asked about plants in the workplace, 97% of
employees would like to have more plants (Husti et al.
2015) because they perceive plants provide a sense of
relaxation, make the work environment more similar to
space at home, cheer up the image of the office, give a
sense of relief, and improve work motivations. Employees
without an outdoor view from their desk are five times
more likely to put a plant in their office than those with an
outdoor view (Bringslimark et al. 2011). Office employees
with an outdoor green view were happier and had
positively associated higher productivity and job satisfac-
tion levels (Lottrup et al. 2015).
In elementary-level classrooms, green walls (described
as a wall with green plants) can provide restorative impacts
to school children. Results show that children in class-
rooms where a green wall was placed scored better on tests
for selective attention (van den Berg et al. 2017). The green
wall also positively influenced children’s classroom
evaluations. When integrating a school garden into the
curriculum, children’s physical activity was increased and
sedentary behavior decreased (van den Berg et al. 2017).
Children who received breaks and time outside exhibited
improved concentration (Duvall and Sullivan 2016). Just
placing plants in the classroom improved performance,
with children progressing through school curriculum 20-
26% faster (van Duijin et al. 2011).
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Reduced effects of dementia
Participants in outside horticultural therapy activities
such as gardening or landscaping are more actively
engaged, have reduced incidents of aggressive behavior,
and improved cognitive capacity (Gigliotti and Jarrott
Improved Self-Esteem
Natural green space has long been used in the promotion
of human well-being through green exercise (exercise in a
greenspace or outdoors) for improvements on mental
health and self-esteem (Townsend and Weerasuriya
2010). A multi-study analysis assessed the best regime of
green exercise that is needed to improve self-esteem and
mood (Barton and Pretty 2010). Dose responses for both
intensity and duration showed large benefits from short
engagements in green exercise, and then diminishing but
still positive returns (Barton and Pretty 2010). Every green
environment improved both self-esteem and mood and the
presence of water generated greater effects. Both men and
women exhibited similar improvements in self-esteem after
green exercise, though men showed a more positive
difference in mood.
Consumers have historically shown an inclination to
purchase products that enhance their quality of life (Hall
and Dickson 2011), meaning they will purchase items that
positively influence their social, physical, psychological,
cognitive, environmental, and spiritual well-being. Plants
in native and improved landscapes (and interiorscapes)
have been documented to influence each of six quality of
life constructs. This paper focused on providing evidence
from the literature regarding the emotional and mental
health benefits associated with plants, thereby influencing
the psychological and cognitive well-being constructs of
quality of life. This research should be strategically
incorporated into both industry-wide and firm-specific
marketing messages that highlight the quality of life value
proposition in order to maintain the industry’s sense of
value and relevance to consumers of the future.
Literature Cited
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... Substantial literature supports the multitude of health and wellness benefits plants provide to people. Hall and Knuth [10][11][12][13] assimilated and categorized the many plant benefits into emotional and mental health [10], physiological health [11], and social benefits [12,13]. Emotional and mental health benefits include enhanced memory and reduced depression, reduction in anxiety, and greater life satisfaction [10]. ...
... Substantial literature supports the multitude of health and wellness benefits plants provide to people. Hall and Knuth [10][11][12][13] assimilated and categorized the many plant benefits into emotional and mental health [10], physiological health [11], and social benefits [12,13]. Emotional and mental health benefits include enhanced memory and reduced depression, reduction in anxiety, and greater life satisfaction [10]. ...
... Hall and Knuth [10][11][12][13] assimilated and categorized the many plant benefits into emotional and mental health [10], physiological health [11], and social benefits [12,13]. Emotional and mental health benefits include enhanced memory and reduced depression, reduction in anxiety, and greater life satisfaction [10]. Psychological health benefits include better sleep, reduced diabetes, enhanced immunity, and decreased mortality [11]. ...
Full-text available
Ornamental plants provide many benefits to humans, including those that affect emotional/mental health, physiological health, social interactions, and economic/financial conditions. However, research related to consumers’ perceived value of ornamental plants has focused primarily on production methods that were used to produce plants, while consumers’ perceived intrinsic value of postpurchase benefits has not been addressed. There is potential for benefit information to generate value for consumers. Knowing consumers’ value for different plant benefits serves to inform green industry stakeholders as they consider their marketing strategies and whether to include benefit information as a part of their plant promotions. An online survey was conducted to elicit U.S. consumers’ willingness to pay (WTP) for lavender plants while displaying different plant benefit information. Participants randomly viewed one of eight plant benefit messages and indicated the maximum they were willing to pay for a lavender plant displaying that benefit. The benefits messages were categorized as cognitive, social, physical, emotional, environmental, aesthetic, educational, and economic based on prior literature. Tobit models were used to analyze the data. Compared to economic benefit information, the social benefit generated the largest premium (USD 6.75). Plant spending in 2020 and household income increased participants’ WTP for the lavender plants. Age had a negative impact on WTP.
... Some hormones and neurotransmitters include dopamine, serotonin, endorphins, oxytocin, gamma-aminobutyric acid (GABA), melatonin, dopamine, etc., each of which has the ability to create positive emotions [1][2][3][4]. Serotonin, for example, is responsible for a variety of functions, including elevating mood and reducing symptoms of depression [5]. ...
... Plants may have a variety of beneficial impacts on pain, sleep, anxiety, and mood. For instance, the scents of certain plants, such as lavender, chamomile, rose, and orange oil, have been known to have calming effects [5][6][7][8][9][10]. Additionally, some plants are capable of producing essential oils that have demonstrated the capacity to exert beneficial effects on an individual's mental well-being [6,[8][9][10]. ...
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Diverse chemical messengers are responsible for maintaining homeostasis in the human body, for example, hormones and neurotransmitters. Various Hawaiian plant species produce compounds that exert effects on these messengers and the systems of which they are a part. The main purpose of this review article is to evaluate the potential effects of Hawaiian plants on reducing pain and anxiety and improving sleep and mood. A comprehensive literature search was conducted in SciFinder, PubMed, Science Direct, Scopus, Google Scholar, and Scientific Information Database between 2019 and 2023 to identify related articles. Results indicate that several Hawaiian plant species, such as M. citrifolia and P. methysticum, have medicinal properties associated with these effects. These plants have been used in traditional Hawaiian cultural practices for centuries, suggesting their potential to benefit human health and well-being. This review presents a comprehensive analysis of the available evidence concerning the potential impacts of Hawaiian plants on sleep, anxiety, mood, and pain.
... The evidence of health and general wellbeing benefits of time spent with plants is now well established (Leavell et al 2019, Hall &Knuth 2019a andb). Since the work on faster recovery time in hospital when patients had a view of a tree (Ulrich 1984) there is now a huge number of studies examining something that, too many, seems obviously to be the case. ...
... With mental health benefits there are sometimes elements of self-reporting, interviews or questionnaires, but again biological markers are also used. For example, the type of biological markers used for measuring reduction in stress and anxiety include: heart rate, skin conductance recovery, concentrates of cortisol, changes in nerve activity, EEG brainwave amplitude and frequency, EEG plus eye tracking, cerebral oxygenation levels, salivary amylase levels, cytokines in blood samples, near infrared spectroscopy, and functional magnetic resonance imaging (Hall & Knuth 2019a). ...
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This handbook is currently in development, with individual articles publishing online in advance of print publication. At this time, we cannot add information about unpublished articles in this handbook, however the table of contents will continue to grow as additional articles pass through the review process and are added to the site. Please note that the online publication date for this handbook is the date that the first article in the title was published online. For more information, please read the site FAQs.
... In the vast, subsequent literature on biophilia, the main prediction that is tested is the idea that biophilia can increase individual meaning and personal fulfillment (see Bratman et al., 2012;Wells & Rollings, 2012;Hartig et al., 2014;Capaldi et al., 2015;Chawla, 2015;Hall & Knuth, 2019a, 2019b, 2019c, 2020. However, for this prediction, and in some cases, for all five predictions, biophilia is defined (either directly or indirectly) as an attraction to nature. ...
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E.O. Wilson proposed the concept of biophilia as “the innately emotional affiliation of human beings with other living organisms.” While the idea has gained traction in diverse fields, including architecture and horticulture, the few empirical tests of the biophilia hypothesis are either inconclusive or fail to provide support. This paper reviews fundamental flaws in Wilson's biophilia hypothesis and proposes “the Biophilia Reactivity Hypothesis”: biophilia as a temperament trait, a theory that offers a falsifiable version of Wilson’s original concept.
... Moreover, our research supports the notion that patients with plants in their rooms experience reduced stress and anxiety, improved pain tolerance, and overall satisfaction with their hospital stay. These results are consistent with those of previous studies conducted in a hospital setting that indicated that the presence of indoor plants can have a holistic positive impact on patient well-being (Hall and Knuth 2019). ...
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Patient recovery and well-being in healthcare settings can be influenced by various factors, including the stress induced by hospitalization and medical care. This study investigated the impact of indoor plants on patient recovery in dental clinics using state-of-the-art techniques to address the limited evidence supporting the claim that nature can alleviate stress and pain in hospitals. Thirty patients were randomly assigned to either a room with indoor plants or a control room without plants for a duration of 5 minutes after their treatment. Physiological responses were assessed using electroencephalography (EEG), heart rate variability, and skin conductance, whereas psychological responses were evaluated using the State-Trait Anxiety Inventory (STAI) and a visual analogue scale (VAS). The results revealed a significant increase in alpha wave power in the frontal region, indicating enhanced relaxation, as well as a significant increase in parasympathetic activity, suggesting improved autonomic balance. Furthermore, a significant decrease in skin conductance was observed when indoor plants were present compared with their absence, indicating reduced physiological arousal. Psychological assessments using the STAI demonstrated lower levels of stress and anxiety, whereas the VAS indicated reduced pain intensity among participants. Overall, these findings suggest that the presence of indoor plants contributes to patients’ relaxation and improved coping mechanisms during the recovery process. This study highlights the significance of incorporating indoor plants into healthcare settings to enhance patients’ overall well-being and promote positive recovery outcomes.
... Photosynthesis of forest and grassland in spaces with high rates of greening may promote the local production of a high-concentration "oxygen bar" environment [60], similar to a business place, but for people to breathe oxygen. When residents walk and rest in such a high-oxygen environment, their cerebral cortex and brain activities are strengthened, which may promote the absorption of oxygen, accelerate blood circulation, invigorate the spirit, eliminate fatigue, and improve immunity [61,62]. Second, it improves the comfort of leisure and improves mood [63,64]. ...
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The greening of land plays a meaningful role in improving human settlements by regulating ecosystem functions in the central coast region of China. However, research on the spatiotemporal heterogeneity of green land changes in different urbanized regions and the cooling temperature effect of the different green land densities are still lacking in this region, which limits the understanding of the effect of greening of land on land thermal properties. To address this issue, we integrated several approaches to establish a comprehensive way of ‘human–computer interactive interpretation method—urban interior mixed pixel model—surface radiation energy balance model’ using data from remote sensing images and the national land use/cover database of China, focusing on Rizhao city. The conclusions are as follows: The total greening of land from 2000 to 2022 was monitored, and it was found that its cover improved within the built-up area of the city, with the proportion of green land increasing from 25.34% in 2000 to 42.98% in 2022. Differences in the amount of green spaces in different urbanized regions were first observed, namely, the urban greening rate was 37.78% in the old urban area in 2022, while it was as high as 46.43% in the newly expanded urban area in 2022, showing that more attention should be given to the construction of urban green spaces during urban expansion. Thermal comfort indicators in the study area were evaluated in terms of latent heat flux (0–457.83 W/m2), sensible heat flux (0–645.09 W/m2), and total available energy (254.07–659.42 W/m2). We also found that the cooling temperature effect in the middle- and high-density green land regions were 1.05 °C and 2.12 °C higher than those in the low-density region, and the established comfort/discomfort zones in terms of land surface temperature were depicted. These results provide a new practical reference for exploring the spatiotemporal heterogeneity change in green land and its impact on land-surface thermal properties in coastal regions.
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Maintaining and caring for residential landscapes is a crucial aspect of homeownership in the United States. For homeowners in the United States, residential lawns represent a significant economic investment, signal their social commitments, and reflect their personal characters. To investigate the differences in Florida homeowners’ priorities regarding residential landscape features, an online survey of 1220 homeowners was conducted. Four different groups of homeowners were identified based on their perceived importance of the four landscape features, namely, environmental, financial, aesthetic, and psychological benefits. Factors such as environmental and financial attitudes and social norms influencing homeowners’ decision-making were examined. The findings revealed that homeowners’ knowledge of landscaping practices and environmental attitudes impact their prioritization regarding landscape features.
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During the Covid-19 pandemic, people experienced many changes in their daily lives. These changes trigger stress and lead to depression in the community, especially among young adults, which is the main axis that leads to low subjective well-being. Various studies have shown that raising pets (dogs and cats) and plants (gardening) can improve an individual's subjective well-being. The study used a qualitative descriptive method with 10 subjects divided into three groups, namely the group of pets, the group of plants (gardening), and the group of pets and plants (gardening). All subjects in the three groups showed high subjective well-being through raising pets and plants (gardening) during the Covid-19 pandemic. All subjects show positive emotions and enjoyed raising pets and plants (gardening). In addition, most of the subjects also felt satisfied with their lives during the Covid-19 pandemic with the presence of pets and plants (gardening). All subjects felt the presence of pets as entertainers to provide motivation. For the subjects, plants (gardening) play a similar role, through the beauty and growth of the plants.
The goal in this chapter is to examine the differences (and points of confluence) between the worldviews of the Global North and Global South on the ecology of cities and their ecosystem services. The chapter is hinged on the distinctions between biophilia and spiritualisation of urban nature in the two global regions, respectively. This is in view of modernisation, westernalisation, and globalisation that tend to universalize urban nature. These ideologies framed the hitherto subsistent planning and building regulations in many former colonies in the Global South, including the Yoruba cities that form the South-west of Nigeria. While both biophilia and spiritualisation of nature lead to human wellbeing through apparently similar experiences of nature, the pathways of their mechanisms are different, with some points of confluence on biophilia. The chapter is structured to achieve the following objectives: (1) evaluate biophilia in Yoruba cities to underpin the significance of urban ecosystem services to human wellbeing in ecological urbanism; (2) assess the cultural practises of horticultural gardening in private and public spaces of Yoruba cities; (3) analyze dialogues on spirit ontologies and mysticism as cultural ecosystem services in Yoruba urbanism. Accordingly, the chapter is replete with discussions on biocentric indigenous lifestyles of Yoruba people on strategies of shaping the natural environment for human wellbeing. It showcases biophilia as a major portion of ecological urbanism within cultural context where respondents cited their innate connection with the nonhuman nature as the authority of God. Ecosystem services of horticultural plants in urban settings discovered in the study include security, safety, aesthetic appreciation, medicinal purposes, and mysticism, among others emerge. Large commercial horticultural gardens in the cities are described as healing gardens in view of the therapeutic ecosystem services of the richly colourful plants and aromatic fragrance of their flowers. The chapter concludes with recommendations on means of achieving balance between biophilic goals and spiritualisation of nature in Yoruba ecological urbanism. The next chapter of the book focuses on the formulation of evidence-based design and planning strategies for translating the indigenous knowledge system of Yoruba people on urban ecosystem services into policy tools.KeywordsBiophiliaSacralisation of natureUrban natureMysticismUrban horticulture and agricultureHuman-nonhuman connectedness
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The purpose of this study was to investigate the effect of two-hour exposure to a forest environment on cytokine, anti-oxidant and stress levels among university students and to compare the results to those measured in urban environments. Forty-one subjects were recruited. For our crossover design, subjects were divided into two groups based on similar demographic characteristics. Group A remained in the urban environment and was asked to perform regular breathing for 2 h. Blood samples were collected and the serum levels of cytokines including interleukin-6 (IL-6), IL-8, tumor necrosis factor-α (TNF-α), and glutathione peroxidase (GPx) were examined. Subjects were moved to a small town in a rural area for an equal amount of time to exclude carryover effects, and then remained for another 2 h in a forest environment. The second set of blood samples was collected to assess the effect of exposure to the forest environment. Using the same method, Group B was first exposed to the forest environment, followed by exposure to the urban environment. Blood samples collected after the subjects were exposed to the forest environment showed significantly lower levels of IL-8 and TNF-α compared to those in samples collected after urban environment exposure (10.76 vs. 9.21, t = 4.559, p < 0.001, and 0.97 vs. 0.87, t = 4.130, p < 0.001). The GPx concentration increased significantly after exposure to the forest environment (LnGPx = 5.09 vs. LnGPx = 5.21, t = −2.039, p < 0.05).
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The objective of this study was to compare physiological and psychological relaxation by assessing heart rate variability (HRV), prefrontal cortex activity, and subjective indexes while subjects performed a task with and without foliage plants. In a crossover experimental design, 24 university students performed a task transferring pots with and without a foliage plant for 3 min. HRV and oxyhemoglobin (oxy-Hb) concentration in the prefrontal cortex were continuously measured. Immediately thereafter, subjective evaluation of emotions was performed using a modified semantic differential (SD) method and a profile of mood state questionnaire (POMS). Results showed that the natural logarithmic (ln) ratio of low frequency/high frequency, as an estimate of sympathetic nerve activity, was significantly lower while performing the task with foliage plants for the average 3 min measurement interval. Oxy-Hb concentration in the left prefrontal cortex showed a tendency to decrease in the 2–3 min interval in the task with foliage plants compared to the task without plants. Moreover, significant psychological relaxation according to POMS score and SD was demonstrated when the task involved foliage plants. In conclusion, the task involving foliage plants led to more physiological and psychological relaxation compared with the task without foliage plants.
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The stress and disorders of the urban life and the pollutions in the large cities such as Istanbul, have made the social and individual health decrease, and therefore it is necessary that some tact be considered in order to diminish these negative effects. The aim of this study is to examine whether there is a relation between restorative gardens in the city and stress. In other words, can restorative gardens surrounding residential homes in cities help to create a less stressful everyday environment? This paper will begin with a cursory overview of a broad concept of stress, health and wellness and proceed to examine in detail Ulrich's Theory of Restorative Garden Design and its implications for gardens in cities. Research shows that benefits would accrue to society as a whole if these design features were implemented on a wide scale.
Green industry firms have competed for decades on the basis of quality and service. While these competitive dimensions are still important, the industry has continued along its path of maturation and firms must incorporate other factors into their value proposition in order to be successful in this hypercompetitive market. Given the recent economic downturn of 2008–2009, consumers are more value-conscious than ever, but are still willing to consume, and pay premiums for, products and services that enhance their quality of life. This paper summarizes the peer-reviewed research regarding the economic benefits, environmental benefits (eco-systems services), and health/well-being benefits of green industry products and services that serve to enhance the quality of life for consumers.
This study investigates the momentary association between urban greenspace, captured using Normalized Difference Vegetation Index (NDVI) derived from Landsat imagery, and psychological stress, captured using Geographic Ecological Momentary Assessment (GEMA), in the activity spaces of a sample of primarily African American adolescents residing in Richmond, Virginia. We employ generalized estimating equations (GEE) to estimate the effect of exposure to urban greenspace on stress and test for moderation by sex, emotional dysregulation, season, neighborhood disadvantage, and whether the observation occurs at home or elsewhere. Results indicate that urban greenspace is associated with lower stress when subjects are away from home, which we speculate is due to the properties of stress reduction and attention restoration associated with exposure to natural areas, and to the primacy of other family dynamics mechanisms of stress within the home. Subjects may also seek out urban greenspaces at times of lower stress or explicitly for purposes of stress reduction. The greenspace-stress association away from home did not differ by sex, emotional dysregulation, neighborhood disadvantage, or season, the latter of which suggests that the observed greenspace-stress relationship is associated with being in a natural environment rather than strictly exposure to abundant green vegetation. Given the association of urban greenspace with lower stress found here and in other studies, future research should address the mediated pathways between greenspace, stress, and stress-related negative health outcomes for different population subgroups as a means toward understanding and addressing health disparities.
Purpose: Exposure to nature and natural environments may be beneficial for mental health; however, most population-based studies have been conducted among adults whereas few have focused on adolescents. We aimed to investigate the relationship between both greenness (vegetation) and blue space (water), and depressive symptoms among teenagers in the United States. Methods: The study population included 9,385 participants ages 12-18 in the 1999 wave of the Growing Up Today Study. We characterized greenness exposure using the Normalized Difference Vegetation Index at a 250-m and 1,250-m radius around a subject's residence using data from the moderate-resolution imaging spectroradiometer onboard the National Aeronautics and Space Administration's Terra satellite. Exposure to blue space was defined as the presence of blue space within a 250-m and 1,250-m radius and distance to the nearest blue space. We used logistic regression models to examine associations with high depressive symptoms, measured using self-reported responses to the McKnight Risk Factor Survey. Results: An interquartile range higher peak greenness in the 1,250-m buffer was associated with 11% lower odds of high depressive symptoms (95% confidence interval .79-.99). Although not statistically significant, this association was stronger in middle school students than in high school students. No such association was seen for blue spaces. Conclusions: Surrounding greenness, but not blue space, was associated with lower odds of high depressive symptoms in this population of more than 9,000 U.S. adolescents. This association was stronger in middle school students than in high school students. Incorporating vegetation into residential areas may be beneficial for mental health.
This paper explores how everyday encounters with two natural phenomena -natural elements and daylight- influence affect and stress levels for people differing in mental health. Nature and daylight exposure both have well-documented beneficial effects on mental health and affect but to what extent their exposure has beneficial effects in daily life is currently under investigated, as is the question whether lower mental health would make one more, or instead, less responsive. To this end, an ecological momentary assessment protocol was employed for a period of 6 days. Fifty-nine participants varying in level of depressive symptoms from none to clinical completed momentary assessments of affect, stress, and their physical environment. Results indicate beneficial effects of nature and daylight on affect and some effects on stress and stress-related outcomes. For nature exposure, but not for daylight exposure, effects were stronger for those in higher need of restoration, stressing the importance of our everyday environment for mental wellbeing.
Tranquil environments can provide relief from stresses of everyday of life and can be considered restorative environments. This paper considers the effects of “greening” urban environments to enhance tranquillity and ultimately well-being and health benefits. A number of studies have been conducted at the Bradford Centre for Sustainable Environments at the University of Bradford which have examined the effects of natural features on ratings of tranquillity. These include quantifying the effects of the percentage of natural and contextual features and soundscape quality on rated tranquillity. Recently the resulting prediction equation TRAPT (Tranquillity Rating Prediction Tool) has been used to examine a number of scenarios including city parks and squares, country parks and moorland areas and validated using tranquillity ratings made by visitors to these green spaces and their reported levels of relaxation. In this paper TRAPT is used for predicting tranquillity in city squares of different sizes, to examine rated tranquillity behind natural (green) and manufactured noise barriers and to predict changes in urban streets of introducing avenues of trees, hedges and grass verges. Using such scenarios this paper demonstrates how the application of TRAPT can enable changes in tranquillity to be estimated. This can provide planners, environmentalists, civic leaders and concerned citizens with a further tool to guide improvements in the urban environment by “greening” measures and noise reduction of various kinds and to help counter threats such as over development, tree removal or traffic densification that might threaten existing benefits.