Soil Microbes and Health: Natural Gardening Anti-Depressants

You may have heard of the mental health benefits of gardening, but did you know that soil is scientifically proven to reduce depression and anxiety? Former organic farmer Logan Hailey digs into the research and explains how you can enjoy better mental health while growing plants.

Written by Logan Hailey Horticulture review by Lorin Nielsen Last updated: January 9, 2024 | 9 min read

A person gently repots cheerful yellow flowers, complemented by a vibrant pink blossom in the background. The delicate petals are carefully transferred from an old pot to a new one filled with fresh soil. A small shovel is gently employed to secure the plant's roots, ensuring its proper support.

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Soil microorganisms are the key to a thriving garden: they break down compost, build soil structure, fix nitrogen, prevent plant diseases, improve crop productivity, and make food more nutrient-dense for humans.

But wait, there’s more! Scientists have recently uncovered that these invisible soil bacteria and fungi directly impact our brains via the same pathways as antidepressants, and specific gardening activities can improve these effects.

If you’re wondering why you feel so dang good after a day in the garden, it may be because soil microbes boost your serotonin and dopamine levels while lowering stress and anxiety. Let’s dig into the research of soil-powered antidepressants and how you can enjoy more mental health benefits as a gardener.

Can Gardening and Dirt Bacteria be Antidepressants?

A close-up view of a hand, with its fingers caked with rich, dark soil, gently arranging the soil around a succulent plant in a pot. The slightly damped scattered soil hints at the hands' recent gardening activities. — Gardening’s serotonin-boosting soil effects are scientifically linked to improved mental health as a natural mood enhancer.

There is a clear link between healthy soil, gardening activities, and improved mental health. Soil microorganisms like Mycobacterium vaccae are scientifically proven to activate the same serotonin-producing neurons as antidepressant medications like Prozac. Serotonin is a key “happy chemical” neurotransmitter that directly impacts mood and emotions.

Research shows that cancer patients exposed to the bacterium had significantly less pain, better cognition, and higher reports of happiness. Moreover, dozens of studies about gardening and mental health prove that gardening is a highly beneficial intervention for depression and anxiety.

Sunshine, fresh air, and healthy homegrown food are obvious benefits for happy gardeners, but it’s exciting to know that more is happening beneath the surface! A fascinating complexity of neuroscience and soil microbial interactions awaits to be studied more deeply. Ancient civilizations have heralded the healing benefits of gardening, and we don’t necessarily need scientific studies to understand that nature makes us feel good. Still, modern advancements and research into therapeutic horticulture offer a breakthrough for medically valid treatments for depression and other psychological disorders.

8 Mental Health Benefits of Gardening, Proven by Science

Just an hour in the garden on a summer day can brighten your mood and help conquer the blues. But this mental boost is far more than a placebo effect! The mental health benefits of gardening are an increasingly popular area of research with tremendous potential for healing the mind and body.

In a society burdened by chronic stress, depression, anxiety, social isolation, and substance abuse, the science of gardening therapy offers hope in all of these realms and more. Reconnecting with the soil may be a vital piece of the puzzle for helping lift our spirits through hard times.

1. Is Dirt the New Prozac? Proven Antidepressant Effects

A close-up photo of a hand holding a handful of rich, dark soil. The crumbly texture of the soil suggests a healthy balance of sand, silt, and clay, allowing for optimal drainage and aeration. — Planting in the morning or evening, avoiding midday sun, protects roots from stress during transplanting.

Dubbed “soil’s Prozac,” Mycobacterium vaccae is the most well-studied soil bacteria that mimics the effects of antidepressant drugs. Studies in humans and mice show that the bacteria triggers a serotonin release, creating an overall sense of well-being and reduced anxiety.

This association was first discovered in 2004 by an oncologist trying to reduce cancer symptoms in lung cancer patients. Researchers injected patients with a killed strain of M. vaccae bacteria and found that they reported “significantly improved quality of life.” While the bacteria did not ease cancer outcomes, it did improve brain function and feelings of happiness.

The antidepressant effects of this soil bacteria were later proven to activate the same neural pathways as Prozac. Mice inoculated with M. vaccae experienced activation of specific serotonin-producing neurons in their brains. They also showed positive behavioral responses like increased excitement and reduced anxiety.

While both of these studies injected the soil bacteria in a lab setting, you don’t need to use any medical devices to reap these benefits. Simply smelling, inhaling, or holding healthy soil in your bare hands can offer just as much of a positive impact on your serotonin levels.

2. Improved Mood

A close-up of a gloved hand, adorned with a floral design, uprooting a plant from a pot. Soil is still clinging to the roots, suggesting that the plant was recently uprooted. The hand's grip on the plant is firm, but gentle, suggesting that the person is careful not to damage the plant. — Gardening and getting your hands in the soil boosts mood and reduces stress.

It’s hard to have a bad day in the garden. Even if it’s muddy and gloomy or you’re pulling weeds, there is something so peaceful about spending time with your hands in the soil. Turns out that this also has a scientific backing in communities worldwide.

A study in Japan found that community-based garden programs improve mood and reduce stress, but only under certain conditions! The group that only observed a community garden did not experience the mood boost. Only the group that participated in planting flowers experienced a dramatic mood increase.

We don’t know if it was the skin-to-soil contact or the physical activity that made the activity so effective, but it’s clear that simply sitting in the garden isn’t as beneficial as doing garden work. I hypothesize that people who want the greatest daily mood boost should get their hands dirty whenever possible!

In a UK study of allotment gardening, mood and self-esteem were significantly improved in gardeners compared to non-gardens. The growers experienced less depression, more confidence, more vigor, and less mood disturbance throughout the day. Perhaps getting out in your garden before or after a stressful day could help you sustain a balanced, peaceful mind state long after the garden work is done.

3. Stress Reduction

A booted foot firmly pressing down on one side of a shovel, plowing rich, dark, and fibrous soil that easily yields to the pressure. A variety of plants in the background flourish under the warm sunlight. — Gardening reduces cortisol levels and can improve your mood in just 30 minutes.

Chronic stress is practically synonymous with the modern Westernized lifestyle. Whether it’s the mental stress of work, finances, world news, or the physical stress of sedentary living, environmental toxins, and poor diet, continuous stress hinders our ability to enjoy life as the happiest, healthiest version of ourselves. Fortunately, gardening can help with this, too!

Our bodies are designed to withstand sudden, acute stressors like being chased by a lion or finding shelter from a storm. However, living in a prolonged state of stress is extremely harmful. Chronic stress is linked to many modern diseases, from anxiety to obesity to heart disease and beyond.

When your body is stuck in a stressed-out “fight or flight” mode, it activates the sympathetic nervous system. This temporarily diverts energy, blood, and oxygen to help you escape danger. A hormone called cortisol is also released in large amounts. Also known as the “stress hormone,” high cortisol levels increase your risk for other health problems. It also just makes you feel more tense and anxious.

Our lovely gardens offer respite. One study found that just 30 minutes of gardening significantly dropped participants’ cortisol levels and improved their moods. Another study showed that gardening helps to distract us from the stressors of our lives, alleviating depression and stopping us from ruminating for too long about the bad stuff.

Next time you’re feeling overwhelmed, grab your shovel!

4. Improved Cognition

A man gently touches the leaves of their plants, feeling their delicate textures under the warm glow of the golden sunlight. The gardener's hands move with care and tenderness as if inspecting each leaf for signs of health and vitality. — Soil microbes enhance learning and reduce anxiety, making it beneficial to bring kids into the garden.

So soil makes us happier and less stressed, but it can also make us… smarter? The science says yes! Of course, we’ve known all along that our plant-growing communities are full of garden geniuses!

Therapeutic research with dementia patients found that sensory gardens and basic activities like digging in the soil or touching plants improved well-being, sleep, and mental alertness. If you have an elderly parent or grandparent, consider bringing them into the garden a couple of days per week. This precious bonding time creates positive memories and may even help their brains. A tall raised bed is especially useful for ensuring accessibility.

In 2010, another study of the popular “soil Prozac” Mycobacterium vaccae revealed another surprising benefit: faster learning! Instead of injecting the bacteria like some other studies did, researchers simply sprinkled the bacteria onto little peanut butter sandwiches fed to mice. Clearly, there is a much more reasonable way we’d be exposed to this soil bacteria regularly in our gardens!

The mice who ate the bacteria excelled at a maze learning task and showed less anxiety-related behavior. They completed the maze twice as fast as mice who didn’t eat the bacteria. They even had fewer errors, which suggests that exposure to beneficial soil microbes could help with cognition and learning. Researchers concluded that M. vaccae has a beneficial effect on brain function and may reduce anxiety.

What is the moral of the story? Gardening helps your brain, and soil microbes can improve learning. Get your kids out in the garden!

5. Reduced Anxiety

A gardener's hands, clad in white and gray gloves, holding a pair of gardening shears and a freshly cut branch laden with ripe, red tomatoes. A wooden crate overflowing with plump tomatoes sits beside the gardener, hinting at a bountiful harvest. — Gardening, even briefly, each week reduces anxiety by grounding individuals in the present moment.

You know that stomach-churning, restless feeling of not knowing what will happen with a certain situation or person? Yeah, me too! Anxiety is an intense feeling of worry, fear, or uneasiness about the future. While this can be a serious mental health concern that requires professional help, many of us experience varying levels of anxiety regularly. Luckily, just a short time spent gardening every week can reduce anxious feelings.

Interestingly, the anxiety-reduction effects of dirt and roots span across a variety of circumstances and demographics. Gardening significantly lowered anxiety during the 2020 pandemic. In breast cancer patients, interactions with plants enhanced spiritual well-being, reduced cancer-related fatigue, and improved natural killer cell activity. Gardens also serve as safe havens for teenagers facing stress and anxiety in high school.

While anxiety tricks our brains into obsessing over potential bad scenarios in the future, gardening blasts us into the present moment. Somehow, when you’re harvesting tomatoes, watching bumble bees, pruning fruit trees, or sowing flower seeds, the worries of the future just drift away. Slowing down and being present with the natural world is the perfect antidote for a worried, fast-moving mind feeling anxious about the future.

6. Enhanced Self-Esteem and Self-Efficacy

Two gardeners collaborate to plant a new sapling. One gardener, meticulously presses it down around the sapling's base, while the other carefully digs a hole in the soil using a small shovel, providing a supportive foundation for the sapling's growth. The sunlight casts a warm glow on the scene of harmonious collaboration. — Success in planting or harvesting contributes to increased confidence in various life aspects.

Media and pop culture bombard us with ideas of what we should look like or how to act to be accepted. If we don’t live up to those unrealistic expectations, it can often leave us feeling insecure, unimportant, or unworthy.

Low self-esteem is a hidden epidemic most notable among adolescents, but it can affect everyone at any age. Boosting confidence and self-esteem requires a lot of inner work and often the assistance of a mental health professional. Still, gardening activities may provide an extra boost of self-love and a feeling of competency.

In one community college study, psychologists found that a 16-week gardening program dramatically improved students’ self-esteem and academic work. As they experienced more gardening “wins,” like a successful tree planting or a big harvest of peppers, they also felt more confident applying themselves in other areas of life.

A study with older adults showed that membership in a gardening group improved people’s self-perception around aging. Whether observing or participating, they experienced more self-acceptance and connection with like-minded communities! Gardens offer a beautiful place to reminisce about the past and evoke nostalgic memories of childhood gardening and cooking experiences.

Dopamine is the neurotransmitter linked to motivation, pleasure, and satisfaction. Fascinatingly, research shows that dopamine stimulation enhances confidence! So, every little garden task you complete is like a stepping stone toward greater self-belief. When you start growing more things and achieving more goals, your brain starts to register that you are capable, worthy, and more powerful than you think!

7. Social Connection

A bountiful harvest awaits as a gardener gleefully gathers a variety of fresh, vibrant vegetables from their garden. A sturdy wooden crate overflows with an assortment of crisp leafy greens and earthy root vegetables. The healthy produce shimmers under the warm sunlight, promising an abundance of nutritious meals. — Community gardens foster social bonds and cultivate a sense of belonging.

The internet has made us increasingly socially isolated from real-world connections. Community gardening is more important than ever to help us unplug and deepen bonds with our fellow growers.

It’s also helpful to learn from each other’s mistakes, collaborate on big projects (I don’t want to build a greenhouse by myself!), and share the fruits of your labor! Sometimes, you even learn masterful tricks from old-timers or enjoy free plants and cuttings from your neighbors.

Research shows that community gardens create social cohesion. Social cohesion enables people to feel accepted and valued in their community. Growing fruits and vegetables somehow allows us to transcend our differences. In the garden, your age, education, life experiences, religious or political beliefs, income, and skill level don’t really matter.

Even if you garden in your own backyard plot, it is always helpful to strike up plant conversations with your neighbors or join a gardening club. If you feel awkward or don’t know what to say, try one of these easy conversation starters:

Your rose bushes look incredible this year! What’s your secret?
How long have you been growing vegetables? Your kale looks amazing!
What’s your favorite summer garden recipe?
Want to swap cuttings? I have a thriving rosemary bush, and your lavender looks gorgeous.
What is your favorite tomato variety? I’m new to this region, and my favorite heirlooms keep having issues.

8. Mindfulness

A woman gently tends to her potted ornamental plant, lovingly spraying its vibrant green leaves with a handheld sprayer. The plant's lush foliage cascades over the pot, creating a verdant centerpiece amidst a backdrop of other plants. — Cultivate mindfulness in your garden, breathe, and appreciate the sensory moments for tranquility.

If you’re not into meditation, mindful gardening can provide almost the same benefits without requiring that you sit in one place for too long. Mindfulness is the art of being focused and aware of your sensory experience in a given moment without judging or interpreting it. In other words, all you have to do is breathe and exist in your garden while you let your mind relax.

Practicing mindfulness in the garden is another profound way to melt away stress, anxiety, and depression while helping you connect to your inner world. A 48-week-long study of a holistic gardening program in prison found that meditative garden work tremendously improved the mental health and trauma responses of prisoners.

Another study found that mindful indoor gardening with houseplants improved mental well-being among older adults. The positive effects increased with more hours, plants, and years spent caring for houseplants. What a great excuse to add another houseplant to your collection!

Whether indoors or outdoors, you can be more mindful while gardening by using a 5-sense check-in. Pause between tasks and notice what you feel, smell, taste, hear, and see. Tuning into the sound of a bird song and the sensation of roots between your fingers can help bring you into the present moment for a peaceful escape from a wandering mind.

Final Thoughts

The human mind is a fascinating place for creativity and innovation, but it can also become a dark space when we get lost in negative thoughts or worries. Psychological science clearly shows that gardening brightens our mood and helps with various mental health conditions.

Remember, this is not meant to be taken as medical advice or a substitution for professional treatment. We want to inspire you to spend more time with your garden and community so we can all be happier together! If you are struggling with your mental health, please reach out to a licensed professional.

Soil Microbes and Health: Natural Gardening Anti-Depressants

Can Gardening and Dirt Bacteria be Antidepressants?

8 Mental Health Benefits of Gardening, Proven by Science