Anxiety, Depression, and the Power of Dirt

By Eric Levine, Ed.D with Becky Shipkosky

Can you remember the last time you dug in the dirt? About half of us might say, “Sure, I just planted some cabbage and spread mulch last weekend!” As for the other 50 percent, we might have to think back as far as childhood to recall our most recent dirt encounter.

Meanwhile, over 20 percent of people across the developed world experience depression or anxiety in their lifetimes, with widely varying durations, access to care, and outcomes. Therapy and medication are the best-known treatments, but many self-care methods have been found to mitigate the symptoms of these conditions, too.

What does dirt have to do with depression and anxiety? A slowly accumulating body of research has, over the past 15 years or so, begun to reveal a powerful healing mechanism just underneath our feet. That would be dirt! More specifically, growing things in it. Gardening.

Most of us probably have an auntie or neighbor who deeply loves their garden, and it’s easy to view this as a pastime for retired folks, or for those super wholesome types. But, if you ask your neighbor what the appeal is, you may be surprised to learn it’s doing something for him that even the busiest and most serious among us could use more of. He’ll likely mention time to himself, a calming or peaceful feeling, or the unique sense of purpose he gets from watching his plants grow. Spoiler: We all need time alone, peace, and purpose!

Neuroplasticity, in Sickness and in Health

The latest neuroscience around mental health conditions, including depression and anxiety, points to a physiological state, not a mental or emotional state. It would appear that when we inherit depression from a parent, for example, what we’ve actually inherited is a specific set of nervous system patterns. This, then, combined with our learning and experiences, is what “programs” the condition into the brain.

We are most vulnerable to becoming wired for mental illness early in life and later during times of prolonged stress. Via the autonomic nervous system (ANS), these triggering events “teach” the brain to feel unsafe, even when we are safe. Another way to think of this is that the ANS writes the code for the brain, using its experience of the world as its source.

The exceedingly good news here is that we stand a decent chance, even in adulthood, of teaching safety to the brain and writing code that allows us to readily and appropriately switch between “safe” mode and “unsafe” mode. We’ve covered these processes in more depth in a couple of previous posts about the wiring and the unwiring of depression and anxiety, plus the role of the vagus nerve.

Enter a “Dirty” Intervention

If you peeked at our toolkit for unwiring depression and anxiety (linked above), then you’ll know we can take our pick of methods for teaching the ANS to feel safe so it can write new, more versatile brain code. Gardening happens to be one with some compelling recent research establishing it as a full-body reset for an overworked, mis-calibrated, or traumatized nervous system. And, it may even be an especially powerful healing practice because of the way it combines several known anxiety- and depression-reducing elements.

Rhythm and Repetition

At a very basic level, we know that routine is good for mental well-being. Gardening offers a routine that is uniquely imposed. While many of us with dysregulated autonomic nervous systems struggle to create structure for ourselves or stick to routines, we may also resist or resent externally imposed routines.

The plants in our gardens do impose routine upon us, but in a gentle, nature-beckoning kind of way. If we don’t pull the weeds regularly, we see our cultivated plants begin to struggle. There is watering, deadheading, harvesting, and pruning that all must be done when the plants need it. We begin to find a yearly rhythm, too—seed catalog time, plant sale time, last frost date, dry season, blight time, harvest, fall planting. There’s the time of year when you have more zucchini than you can handle, and the time that those certain caterpillars kill all the squash, and “it feels about time to plant the zinnias.”

Depression Essential Reads

Exercise Alone Is Not an Effective Treatment for Depression

6 Ways to Hold Things Together When Your Spouse Is Depressed

This daily, weekly, and seasonal repetition may recondition the ANS in just the way that we need through predictable, sensory-safe repetition (Porges, 2017).

Green Time

Time spent in green space, whether a park, forest, meadow, or garden, reduces stress markers. At the higher level, we already know that time in green space reduces symptoms of depression and anxiety (Kotera et al., 2021). But how does that work? Researchers have found improvements in cortisol levels and blood pressure, as well as HRV (Shuda et al., 2020), a reliable proxy for ventral vagal activation—the body’s natural "calm down" button.

This all points to reduced sympathetic activity (fight or flight) or dorsal vagal activation (freeze), as the case may be, both major contributors to anxiety and depression. When we can do this for ourselves regularly, we begin to teach the brain how to feel safe and how to switch between sympathetic and parasympathetic states in alignment with present reality.

Nature’s Prozac

It seems soil may contain antidepressant and anti-anxiety microbes. Preclinical research indicates that some fungi and bacteria in our soil may influence neurotransmitter production. A bacterium of particular interest, Mycobacterium vaccae, has been found to stimulate serotonin production in mice, improving stress resilience, cognitive function, and more (Matthews et al., 2013; Juarez et al., 2022).

Fertile Soil for Neuroplasticity

When we exercise, receive sunlight, focus our minds, and engage in creativity, as we do in gardening, our neurons increase production of brain-derived neurotrophic factor (BDNF). This protein chemically increases neuroplasticity (Brunoni et al., 2008), creating a better environment for our humble ANS to teach the brain new pathways. We can think of gardening as fertilizer for the brain!

Connection and Community

Many gardeners work alone and benefit profoundly from this time to think through things, listen to their favorite podcast or music, or even meditate. Gardening with others, however, can add a different layer of benefit. Social connection is likely as essential to our mental health as anything else covered here (Porges, 2017), so your community garden may make your healing efforts that much more fruitful.

Beyond social benefits, horticultural therapy programs offer all of the above in a structured and intentional setting, often alongside other modalities. Residential programs with a gardening component can be especially powerful, placing the mental health benefits of communing with the dirt in a 24-hour therapeutic context with a safe environment, talk and group therapy, nutritious food, and medication.

Closing Thoughts

The idea of being able to rewire an anxious or depressed brain is relatively new and may even be hard to conceive of. However, if we visualize our emotional landscape itself as a garden bed, it’s not hard to imagine planting what we want, nurturing it, and plucking or crowding out what we don’t want. Those “weeds” are beneficial perhaps along the roadside or creek bed, but this is your garden, and you get to choose what thrives here. It takes regular, repetitive effort, but there is peace in this work.