FM is widespread, with a worldwide prevalence ranging between 2% and 8% depending on the region. While there is some discrepancy in the literature, FM predominates among women. It tends to peak in people aged between 50 and 60 years of age [6].

The worldwide prevalence of FM increased substantially following the COVID-19 pandemic and continues to rise [6]. Part of the rising prevalence is related to increased awareness of a syndrome that is not easily diagnosed by an objective diagnostic test. Moreover, updated diagnostic criteria from the American College of Rheumatology have made it easier for general practitioners to confirm a diagnosis [7]. Other contributing factors are likely related to heightened psychological stress and technological shifts that both promote social isolation and have elevated rates of unemployment.

FM imposes a tremendous socioeconomic burden worldwide, partially a result of the high frequency of comorbid mental illness [4]. Reduced performance both in the work and household is well-documented. Per one study, an average of more than 5 days of work were lost over three months, with household productivity reduced by days over the same period of time [8]. Moreover, FM has resulted in increased healthcare utilization and increased disability claims. Accordingly, a systematic review published in 2022 analyzing data from 10 different countries estimated direct annual costs that range from $1,250 to $35,920 per patient [9].

HT is a structured therapeutic intervention that uses engagement with plants and natural environments to achieve designated health-related goals. Activities include gardening, cultivation, flower arranging, guided interaction within natural settings, and nature-oriented mindfulness practices. Interventions are typically led by trained horticultural therapists or multidisciplinary teams that may include occupational therapists, psychologists, and rehabilitation specialists [14]. Underlying therapeutic mechanisms are primarily grounded in neuroendocrine stress regulation and biopsychosocial behavioral interventions [15].

Stretching back to ancient times, records indicate that Hippocrates promoted the healing power of nature. Likewise, medieval monasteries integrated farming into care for the sick. In the 1800s, farming was integrated into hospitals and asylums treating mental health patients. During the early 1900s, agricultural work was more systematically woven into the therapeutic programs offered in hospitals and sanatoria. Especially with the onset of World War, horticulture was recognized as a crucial element in the treatment of patients with physical or mental problems [16].

The first book describing HT was published in 1961. Subsequently, the granting of awards and the founding of a formal association for HT-affiliated work crystallized its place within the field of medical treatment. Over the next couple of decades, concepts of green care and care farming gained increased traction as a therapeutic modality for a wide range of conditions, including for patients with physical disabilities and histories of substance abuse. In parallel, increased research related to the field ushered in a large rise in the creation of care farms in many parts of the world around the turn of the 21st century [17].

To date, clinicians have largely focused on the use of HT in the management of psychiatric disorders and conditions of cognitive impairment. Recent evidence shows that integrating structured HT into the rehabilitation of patients with schizophrenia significantly enhances personal competence, mental well-being and participation in daily activity [18]. Others have illustrated the efficacy of HT in reducing levels of anxiety in diverse populations [19]. HT also has been shown to modulate stress, improve quality of life and enhance indices related to post-traumatic stress disorder (PTSD) in a group of veterans [20].

Multiple studies have also looked at the benefits of including such therapies in the treatment of elderly people. One group showed that HT resulted in weight loss, lower levels of stress-related hormones, increased flexibility, improved diet, and enhanced social interactions among seniors [21]. Other papers have described enhanced physical function, quality of life, and mood in older adults. Similarly, horticulture has been demonstrated to improve measures related to cognitive function and agitation among the aged [22].

Despite a growing body of evidence exploring the psychological benefits of HT, relatively little has been written about its role in reducing pain. Nonetheless, one study found that the addition of HT to a program of pain management improved physical health and the ability to cope with chronic pain [23]. Moreover, a palliative care study demonstrated improved indices of pain in hospice patients who engaged in a long-term horticulture intervention [24].

Another group found that in patients with chronic low back pain, an HT intervention improved measures of spine flexion and the perception of pain [25]. Furthermore, a brief course of HT improved several parameters of wellness in a group of veterans, including a military-specific measure of pain’s interference in daily life [26]. A systematic review evaluating adults with persistent pain found that nature-based mindfulness leads to reduced self-reported pain and depression and elevated indicators of quality of life [27].

Despite the overwhelmingly high prevalence of FM and a well-established understanding of the importance of a multidisciplinary approach, few papers could be retrieved specifically exploring the role of some form of HT in the management of FM. In one publication, a large cohort of women with a mean age of 51 with FM participated in a floristry course. Significant persistent improvements were found in assessments of global physical and mental health, standardized surveys evaluating depression and anxiety, and an FM impact questionnaire. The effect was partly attributed to relief from stress, a triggering of positive emotions, and decreased attention fatigue [28].

Moreover, performing exercise in a forest resulted in less perceived pain and insomnia and more frequent wellness in people with FM [29]. Similarly, another researcher evaluated women with FM following an intervention involving engagement with flowers, stones, and soil organic matter. They found that the intervention resulted in reduced pain intensity and an elevated threshold to pain [30].

One paper found that in addition to better ratings of pain, depression, anxiety, and insomnia, a guided forest hike boosted affect, mood state, friendliness, and mindfulness in patients with FM and related conditions [31]. Another study performed by some of the same authors found similar results in patients who participated in multi-component nature-related activities over a three-month course. The authors also showed that the intervention improved measures of kinesiophobia and physical activity; cognitive emotional regulation and coping; perceived competence, dominance and self-efficacy; and state of arousal [32]. A summary of the studies evaluating nature-based interventions in FM is provided in Table 1.

Although papers report favorable outcomes, the overall quality of evidence remains limited. Most FM-specific studies included relatively small sample sizes, heterogeneous interventions, and short follow-up periods. Several studies lacked control groups to account for other factors such as social engagement, increased physical activity, or the mere effect of study participation in a study. In addition, outcome measures varied substantially across studies, limiting comparability. Consequently, the available evidence suggests the potential utility of HT but does not permit definitive conclusions regarding its efficacy or superiority over other non-pharmacologic interventions. The major strengths and weaknesses of the current literature are summarized in Table 2.

Although the complex interweaving biological processes underlying the potential benefits of HT remain incompletely understood, several pathways have been proposed. These include stress reduction, autonomic regulation, physical activity, sensory stimulation, neuroendocrine modulation, and neuroimmune alterations. These biochemical changes are hypothesized to interact to influence pain perception, psychological well-being, sleep quality, and functional capacity [15, 33–36].

In a study demonstrating better sleep and less anxiety in subjects who participate in horticultural activities, the authors describe some of the ways plant exposure may benefit human health, including engaging sensory-rich material which activates visual, tactile, and olfactory perception, potentially resulting in an unconscious calming response and a state of greater well-being [33]. Furthermore, the chemical basis of particular plants is suggested to elicit stronger effects. For instance, some plants release volatile organic compounds associated with reductions in stress and depressed mood [37]. Others are thought to promote sedation and enhance sleep quality [38].

Another group showed HT-induced brain changes associated with calmness as evidenced by characteristic electroencephalogram (EEG) patterns [39]. Exposure to nature was also associated with improved memory, attention restoration, and wakefulness. Such findings are supported by preliminary evidence showing that immersion in biodiverse environments may modulate neuroimmune pathways. While direct central NT mechanisms remain complex, exposure to biogenic organic compounds has been correlated with significant reductions in systemic cortisol, which has been linked with cognitive and emotional restoration [40, 41]. These effects could be at least partly explained by the enhanced electrical activity in the occipital lobe, signs suggestive of brain comfort and clear wakefulness [42].

Researchers also propose that dampened stress following HT may be tied to modulated levels of glutamate, an NT linked with excitability and implicated in the pathophysiology of FM and related mood disorders. They have found evidence indicating that these outcomes may correlate with cerebral activity changes within pain-related neural networks. Moreover, it is theorized that pain-associated neuroendocrine pathways could result in a diminished release of stress-related cortisol and norepinephrine [34].

Related works reveal that HT may be associated with increased parasympathetic activity and corresponding reduced physiological markers of stress [35]. This potential shift in the balance in favor of a more tranquil state is illustrated by a decrease in both systolic and diastolic blood pressure and a drop in pulse rate in participants of Shiniri-yoku, the Japanese term for forest bathing. This suggested homeostatic resetting was reflected by a more positive emotional state, improved physiological activity levels, and sustained attention [43].

Some papers have also reported decreases in inflammatory biomarkers following HT interventions. In particular, trends toward reduced interleukin (IL)-6 levels, a cytokine associated with chronic age-related inflammation, have been observed [44]. Moreover, preliminary data showing downregulated cellular immunosenescence markers suggest that HT could protect immune surveillance starting as early as middle age [45]. Nonetheless, these findings remain highly inconclusive and warrant rigorous replication.

Likewise, researchers have postulated that exposure to diverse microbiota during HT could influence immune regulation, potentially regulating autoimmune pathways [36]. Analogously, it is proposed that HT may attenuate the neuroimmune axis, theoretically dampening the secretion of pro-inflammatory cytokines and reducing levels of circulating oxidative stress [34]. While the evidence is conflicting and somewhat controversial, in repeated studies, FM has been linked with dysregulated inflammation, underscoring a currently unverified yet putative therapeutic interface for HT based on these hypothesized pathways [46]. The primary proposed mechanisms are summarized in Table 3.