Is Gardening Good for Your Mental Health? What the Evidence Shows
- The largest pooled analysis, published in Preventive Medicine Reports in 2017, combined 22 studies and found a consistent positive effect of gardening on health, with the caveat that cause and effect are hard to separate.
- In the one sizeable randomised trial, gardeners visited their plot for a median of 90 minutes a week, and most went at least twice a week.
- An RHS and University of Sheffield study put planted containers in 38 bare front gardens in Salford, and the share of residents with a healthy daily cortisol pattern rose from 24% to 53%, but only 16 people gave complete cortisol samples.
- The claim that a soil bacterium works like an antidepressant rests on experiments in which mice were injected with it. Nobody has shown that handling compost does the same for people.
- Low mood or anxiety most days for more than two weeks is a reason to speak to a GP or doctor, whatever is growing on the windowsill.
Articles about gardening and mood tend to say that "studies show" it lowers cortisol, lifts depression and sharpens focus, and then decline to name a single study. This one names them, says how big they were and says what they could not prove. The short version is that the evidence is encouraging and thinner than the headlines suggest.
It also matters what kind of gardening was tested. Nearly all of the research involved outdoor plots, therapy programmes or front gardens. Nobody has run a proper trial on three pots of herbs in a flat, so the small-space plan further down is an honest extrapolation and is labelled as one.
What does the research on gardening and mental health show?
Four pieces of work come up most often. They are worth knowing individually, because they differ a great deal in how much weight they can bear.
| Study | What was done | What was found | How much weight it bears |
|---|---|---|---|
| Soga, Gaston and Yamaura, 2017 | Meta-analysis of 22 studies from the US, Europe, Asia and the Middle East: 12 of horticultural therapy, 7 of everyday gardening, 3 short experiments | A significant positive effect across outcomes including depression, anxiety, life satisfaction and quality of life | Moderate. Many of the included studies were not randomised, and before-and-after designs reported larger effects |
| Litt and colleagues, 2023 (the CAPS trial) | 291 adults in Denver who did not garden were randomly given a community garden plot, seeds, seedlings and a beginners' course, or no plot | Greater reductions in perceived stress and anxiety among gardeners, plus about 1.4 g more fibre a day and about 6 more minutes of moderate-to-vigorous activity a day | The strongest design available. The stress and anxiety results were secondary outcomes, and the margins of error on the fibre and activity differences were wide |
| Chalmin-Pui and colleagues, 2021 (RHS and University of Sheffield) | Planted containers added to 38 bare front gardens of about 10 m² in Salford, with stress measured before and three months after | Perceived stress fell significantly. Healthy daily cortisol patterns rose from 24% to 53% of residents | Limited. 28 people completed the stress questionnaire, 16 gave full cortisol data and there was no control group |
| Green social prescribing pilots, England | 8,339 people with mental health needs referred to nature-based activities, including community gardening, at seven sites | Statistically significant improvement on all four ONS wellbeing questions. Happiness and anxiety moved from worse than the national average to in line with it | Limited. A before-and-after evaluation with no comparison group, and gardening was one activity among several |
The 2017 meta-analysis is the paper behind most "gardening is good for you" headlines. Its authors were careful. They wrote that "untangling the causal relationships between gardening and improved health outcomes is not an easy task", which is a polite way of saying that people who already feel well may be the ones with the energy to garden.
They also detected publication bias, the tendency for positive results to get published and null ones to stay in a drawer, though the overall result held after they adjusted for it. Treat the paper as a consistent signal, not proof.
The Denver trial in The Lancet Planetary Health answers that objection better than anything else so far, because nobody chose which group they landed in. People who started out most stressed improved most. The researchers themselves pointed to the company as much as the plants: the plots were in shared gardens, with classes and neighbours attached.
The Salford front-garden study is the most relevant to small spaces, since the whole intervention was a few containers outside a front door. It is also the smallest. A jump from 24% to 53% sounds dramatic until you remember it describes 16 people.
How much gardening did the studies involve?
Less than you might expect. In the Denver trial, a follow-up analysis in Scientific Reports found that 97 of the 145 people given plots gardened for the whole season. They visited for a median of 90 minutes a week. Some 78% went at least twice a week, and over half stayed 30 minutes or more each time.
In Salford the residents did not have to garden at all in any energetic sense. They received containers already planted with a small tree, shrubs, climbers and bedding, and the job was to water them and look at them. The study ran for three months.
The meta-analysis covered everything from a few hours of experimental gardening to weekly therapy sessions over months to people who gardened daily for years. Its authors could not name a right amount and listed dose as a research priority. Anyone quoting a precise number of minutes for a precise benefit is ahead of the evidence.
What the better studies share is regularity and a reason to go outside. Two or three short sessions a week, kept up for a season, is the pattern with the most support behind it.
Is there really an antidepressant in soil?
Be most sceptical about this claim. It traces back to a 2007 paper in Neuroscience by Christopher Lowry's group, who gave mice a heat-killed preparation of the soil bacterium Mycobacterium vaccae. It was delivered into the windpipe or injected under the skin. The treated mice showed activity in serotonin-producing brain cells and behaved differently in a stress test.
That is interesting immunology. It is a long way from "getting your hands dirty releases serotonin". The mice were dosed with a measured laboratory preparation, not potting compost, and they were mice.
Lowry's group at the University of Colorado Boulder has continued the work, with the stated hope of one day developing a vaccine-style preparation. That tells you they do not regard a bag of compost as the delivery method.
I could find no trial showing that handling soil changes mood in people through this route. If gardening helps, the better-supported explanations are duller: light physical activity, daylight, a task with a visible result and, in community plots, other people.
What does a realistic small-space version look like?
No trial has tested a windowsill, so treat this as a sensible guess built from what the studies had in common: something living that needs you two or three times a week, some of it outdoors if possible, kept up for at least three months. The table shows one way to arrange it.
| What | How often | Time |
|---|---|---|
| Check three to five pots: push a finger into the compost, water only the dry ones, pick off dead leaves | Daily, ideally in the morning | 5 minutes |
| A longer session: sow a tray of salad leaves, pot something on, feed, tidy, harvest | Twice a week | 25 to 30 minutes |
| Something with other people in it: a community garden work morning, a plant swap, a visit to a public garden | Once a month | 1 to 2 hours |
That adds up to about 85 to 95 minutes a week, close to the 90-minute median in the trial. For the pots, the Salford approach is a fair model: one structural plant such as a bay or a dwarf conifer, two or three long-lasting fillers, and one thing you can eat.
On a windowsill, swap the structure for a pot of chives and a tray of cut-and-come-again salad. Our small-space growing guide covers containers and light in detail.
Two cautions. If a dead plant is going to feel like a personal failing, start with the unkillable: mint, chives, a spider plant. And keep the project small enough that a bad fortnight does not wreck it. A balcony that needs an hour a day in July has stopped being restful.
When is gardening not enough?
Gardening is not a treatment for depression or anxiety
The studies above measured stress and wellbeing scores, mostly in people without a diagnosis. None of them tested gardening as a replacement for talking therapy or medication. If you have felt low, anxious or unable to enjoy things most days for more than two weeks, speak to your GP in the UK or your doctor in the US.
In England you can also refer yourself to NHS talking therapies without seeing a GP first. In the US, the National Institute of Mental Health explains how to find a provider.
If you feel unable to keep yourself safe, call 999 in the UK or 911 in the US. Samaritans answer on 116 123 at any hour in the UK, and the 988 Suicide & Crisis Lifeline takes calls and texts in the US.
Do not stop or reduce a prescribed medicine because a hobby is going well. That is a conversation for whoever prescribed it.
Questions readers ask
Do houseplants count, or does it have to be outdoors?
The main studies all involved outdoor growing, so the evidence for houseplants alone is weaker. Indoor plants still give you a regular task and something to watch change, which is part of what the outdoor studies offered. With no outdoor space at all, a monthly community garden session covers the daylight and company that a windowsill cannot.
Does gardening lower cortisol?
One small UK study found that more residents had a healthy daily cortisol pattern three months after planted containers were added to their front gardens: 53%, up from 24%. Only 16 people provided complete samples and there was no control group. It is a promising finding that needs repeating in a larger trial before anyone states it as fact.
How long before you notice a difference?
The Salford study measured change at three months and the Denver trial ran across a full growing season, roughly spring to autumn. Neither tested shorter periods. Give a new growing habit at least a season before judging it, partly because the first few weeks are mostly bare compost.
Is community gardening better than gardening alone?
Nobody has compared the two head to head. The only large randomised trial used shared community plots, and its lead author credited part of the benefit to being outdoors with other people. If isolation is part of what you are dealing with, a shared plot or a volunteering group is the better-evidenced choice.
Sources
- Soga M, Gaston KJ, Yamaura Y. Gardening is beneficial for health: A meta-analysis. Preventive Medicine Reports. 2017;5:92–99.
- Litt JS, Alaimo K, Harrall KK, et al. Effects of a community gardening intervention on diet, physical activity, and anthropometry outcomes in the USA (CAPS): an observer-blind, randomised controlled trial. The Lancet Planetary Health. 2023;7(1):e23–e32.
- Scientific Reports. A process evaluation of a randomized-controlled trial of community gardening to improve health behaviors and reduce stress and anxiety. 2024.
- Chalmin-Pui LS, Roe J, Griffiths A, et al. "It made me feel brighter in myself": the health and well-being impacts of a residential front garden horticultural intervention. Landscape and Urban Planning. 2021.
- NHS England. Green social prescribing.
- Beyond Greenspace, University of Exeter. Green Social Prescribing Test and Learn pilots: national evaluation final report published. 4 September 2024.
- Lowry CA, et al. Identification of an immune-responsive mesolimbocortical serotonergic system: potential role in regulation of emotional behavior. Neuroscience. 2007;146(2):756–772.
- University of Colorado Boulder. Why dirt may be nature's original stress-buster. 9 May 2019.
- NHS. Find NHS talking therapies for anxiety and depression; National Institute of Mental Health. Help for mental illnesses.
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Can a doctor prescribe gardening?
In England, in a sense. Green social prescribing is NHS England's term for a link worker at a GP practice connecting someone to nature-based activities such as walking schemes, community gardening and food-growing projects. A cross-government programme worth £5.77 million tested it at seven sites.
The national evaluation, summarised by University of Exeter researchers involved in it, reported that 8,339 people with mental health needs took part, at an average cost of £507 each. Wellbeing scores improved on every measure. There was no comparison group, so the evaluation cannot show how much of that improvement came from the activity and how much would have happened anyway.
If you are in England and interested, ask your GP surgery whether it has a social prescribing link worker. There is no national equivalent in the US. Community gardens there are usually run by city parks departments or non-profits, and your county extension office can usually point you to one.