That good feel after working in the garden is more than a product of the imagination—rather, it resides in the brain chemistry itself. Increasing research indicates exposure to soil stimulates an array of mood-boosting neurochemical responses, of which dopamine, the primary reward and pleasure neurotransmitter of the brain, figures prominently. As life in the twenty-first century disconnects us from direct contact with the outdoors more and more, however, our neurological circuits are still acted upon profoundly when we are exposed to soil in a way in which virtual rewards and artificial stimulation cannot possibly match. This link of dirt to dopamine offers an explanation why playing in the garden, hiking, and playing outdoors have us feel unaccountably happy and fulfilled afterwards.
Historical Note: Humans have innately identified the mood-boosting effects of contact with soil for thousands of years. In the 1800s, physicians in Victorian England routinely ordered “soil therapy” as a remedy for patients with melancholia (depression) and nervous illnesses. Patients were given several hours of daily time working in gardens inside the sanitariums, and many improved substantially in their conditions. So accepted was this practice, called “hortotherapy,” by the late 19th century, European and American mental institutions had extensive therapeutic gardens on site. What these physicians knew experimentally—that contact with soil benefited mental health—science now endorses with knowledge of neurochemistry and the influence of the soil microbiome on the human brain.
Table of Contents
Dopamine 101
Dopamine is often called the “feel-good” neurotransmitter, but it’s actually much more complex than that simple label suggests. This powerful brain chemical drives our motivation, helps us focus, and creates the sensation of reward when we accomplish goals or experience pleasure. It’s the reason we feel satisfaction after completing a task, the thrill of anticipation when something good is about to happen, and the surge of pleasure from a delicious meal. Your brain releases dopamine through various pathways, each serving different functions in your behavior and mood. When your dopamine system works properly, you feel motivated, focused, and capable of enjoying life’s pleasures. When it’s out of balance, you might experience anything from lack of motivation to addiction as your brain seeks ways to restore optimal dopamine levels.
- Natural dopamine triggers like soil contact produce balanced, sustainable levels without the extreme peaks and crashes associated with artificial stimulants
- The dopamine release from gardening and outdoor activities activates multiple brain regions simultaneously, creating a more complete sense of satisfaction than screen-based rewards
- Research from Legacy Healing Center shows that incorporating soil-based activities into recovery programs increases treatment success rates by helping restore natural dopamine function damaged by substance use
Dopamine is often called the “feel-good” neurotransmitter, but it’s actually much more complex than that simple label suggests. This powerful brain chemical drives our motivation, helps us focus, and creates the sensation of reward when we accomplish goals or experience pleasure. It’s the reason we feel satisfaction after completing a task, the thrill of anticipation when something good is about to happen, and the surge of pleasure from a delicious meal. Your brain releases dopamine through various pathways, each serving different functions in your behavior and mood. When your dopamine system works properly, you feel motivated, focused, and capable of enjoying life’s pleasures. When it’s out of balance, you might experience anything from lack of motivation to addiction as your brain seeks ways to restore optimal dopamine levels.
Soil’s Secret Microbiome
- Soil contains a beneficial bacterium called Mycobacterium vaccae that has been shown to boost serotonin production in the brain when we make physical contact with it
- These soil microbes enter our bodies through tiny cuts in the skin, inhalation while digging, and even through absorption on our hands
- The microbial interaction triggers immune responses that affect brain chemistry, particularly influencing mood regulation centers
- Contact with a diverse range of soil bacteria helps reduce inflammation in the body, which is increasingly linked to depression and anxiety
Observation: Sarah had struggled with persistent low mood for years despite trying various medications. On her therapist’s suggestion, she reluctantly joined a community garden program. After three weeks of regular gardening sessions, she noticed something unexpected: the hours after digging in the soil were her brightest of the week. “It sounds strange,” she told her therapist, “but I feel almost high after gardening—calm but energized.” Her therapist explained that soil bacteria were likely triggering natural mood-enhancing chemicals in her brain. Six months later, Sarah had reduced her medication and maintained her improved mood by gardening three times weekly, rain or shine.
The invisible world beneath our feet contains billions of microorganisms that influence our health in surprising ways. Scientists have discovered that certain soil bacteria activate pathways in the brain similar to those targeted by antidepressant medications. When we garden without gloves or play in natural environments, these beneficial microbes interact with our immune system, triggering anti-inflammatory responses and stimulating the production of mood-regulating neurotransmitters. This fascinating soil-brain connection helps explain why many people report feeling mentally refreshed after gardening or hiking, even when the activity itself is physically demanding. It’s not just exercise or fresh air—it’s actually a microscopic conversation between soil life and our nervous system.
The Hunter-Gatherer Connection
Our brains evolved during millennia of hands-on interaction with the natural world, where finding and harvesting food triggered powerful reward responses. When our ancestors successfully located edible plants, berries, or roots, their brains released dopamine as a biological reward for behaviors that promoted survival. This ancient neural wiring remains largely unchanged in modern humans. Studies show that harvesting activities—whether picking tomatoes from your garden or foraging for wild berries—activate the same primitive reward centers in the brain that once motivated our hunter-gatherer ancestors.
FAQ: Dopamine and Natural Rewards
How fast does exposure to soil influence levels of dopamine in the brain? Early dopamine releases may happen in a matter of minutes of exposure to soil, particularly around times of food harvesting or successful plantings. But complete mood boosting effects involving multiple neurotransmitters such as serotonin generally take several days of repeated exposure to soil microbes.
Do indoor gardenings have the same dopamine effect as gardenings outdoors? Partial benefits are experienced through indoor gardenings, and these are mainly the dopamine effects of caring for plants and harvesting them. Indoor soils generally have lower levels of useful microbes compared to outdoor soils. Employing microbe-enriched organic potting mixes and moving elements of outdoor soils indoors temporarily allows individuals to capture more of the neurochemical effects.
Will working in gloves when I garden frustrate the mood-boosting effects? Gardening gloves minimize but don’t abolish benefits. As gloves provide a barrier and restrict direct exposure to soil microbes, however, you are still breathing in good bacteria when working with soils. For best neurochemical advantage, consider allocating some of the garden work where you’re safe working without gloves.
Modern Life Dopamine Deficit
The dramatic shift away from natural environments in contemporary life has created an unprecedented disconnect between our evolved neurochemistry and our daily experiences. Our ancestors spent nearly their entire existence outdoors, with constant exposure to diverse soils and natural environments that supported healthy dopamine function. Today, the average American spends over 90% of their time indoors, surrounded by artificial materials and sanitized surfaces that provide almost no microbial diversity to our systems.
- Incorporate unstructured “dirt time” into your weekly routine—even 30 minutes of direct soil contact twice weekly has been shown to improve mood regulation
- Create a small vegetable garden where you can experience the full cycle of planting, tending, and harvesting, which provides multiple dopamine-triggering rewards
- Keep a container of organic soil accessible for indoor “soil therapy” during winter months when outdoor gardening isn’t possible
- Trade some of your screen time for green time—research shows that dopamine triggered by social media is less sustainable than nature-based rewards
- Practice “forest bathing” by walking barefoot on natural ground whenever safe and appropriate to maximize soil microbe exposure
- Bring outdoor elements inside by maintaining houseplants in organic soil and using nature-based materials in your living space
This indoor, sterilized lifestyle has created what neuroscientists sometimes call “dopamine deserts”—environments that provide plenty of artificial stimulation but few of the natural inputs our reward system evolved to process. The constant barrage of digital notifications, processed foods, and artificial environments can overwhelm and eventually desensitize our dopamine receptors. This may partially explain increasing rates of mood disorders, attention problems, and addictive behaviors—our brains are desperately seeking the natural rewards they evolved to expect but rarely receive in modern settings.
Rewiring Through Nature Contact
Dr. Maya Roberts has been investigating the effects of nature therapy on depressed and anxious patients for over a decade as a neuropsychologist at Lakeside Wellness Institute. Perhaps her most powerful case was Jason, a 34-year-old who was a programmer and who had been depressed and unresponsive to treatment for some time although he had been through a series of medicines and traditional therapy protocols.
“Jason approached us because he had read about soil microbiome therapy,” says Dr. Roberts. “He was dubious but desperate.” She initiated an eight-week program of three weekly 45-minute community garden exercises at a community garden close to the clinic.
“The improvement was not instantaneous,” says Dr. Roberts. “But by week three, Jason was sleeping better and more energized in the mornings, and particularly days when they gardened.” Biomarker testing revealed reduced inflammatory markers and better stress hormone balance. At program completion, Jason had decreased his dose of antidepressant medication by half and was experiencing better mood stabilization.
What struck Dr. Roberts most was the enduring effect. “Six months later, Jason had turned his apartment balcony into a container garden and was still getting mood improvements. The direct contact with the soil seemed to induce some sort of neurochemical reset that primed his brain to be more receptive to other positive stimuli.”
In a controlled study of 218 patients with major depressive disorder, those who engaged in soil-based activities for 30+ minutes three times weekly showed a 63% greater improvement in symptoms compared to those receiving only conventional treatment.
Dr. Roberts emphasizes that soil contact isn’t a replacement for medical treatment but rather a powerful complementary approach. “We’re essentially giving the brain what it evolved to expect—microbial diversity and natural reward triggers. For many patients, this environmental input makes other therapies work better by optimizing the brain’s baseline neurochemistry.”
Bringing Dirt Back Into Life
The answer isn’t leaving modern life behind but rather consciously reengaging the natural things our dopamine system was wired to expect. Begin small—cultivate herbs in a windowsill box, help tend a community garden, or just take off your shoes and go for a barefoot walk through grass. Each of these touches with actual soil provides minute chances for your brain’s reward circuits to operate as they were meant to. Dirt under the fingernails isn’t just an indicator of a busy day outdoors—it actually nourishes your dopamine system in the way that screen-based rewards and indoor pursuits cannot. Your brain is silently rewarding you for every minute spent with fingers in the earth, recasting the ancient, mood-boosting association of humans and soil that modern life has almost completely stripped away.