Indoor Gardening Could Help Boost Immune Systems, Study Finds

While you may get noticeable joy from feeling the soil outside on your fingers or seeing your first tomatoes pop up on the vine, even indoor gardening can bring some helpful benefits for your well-being, according to a new study.

Researchers from the University of Helsinki, Natural Resources Institute Finland and Tampere University have uncovered the benefits of microbial exposure that happens during urban indoor gardening.

Previous studies have unearthed the benefits of exposure to natural materials rich in microbes, like soil, on the human microbiota, but the researchers in this study looked specifically at whether urban, indoor gardening could have any similar impacts.

When using a microbially rich gardening soil for their indoor gardens, the study participants experienced an increase in microbiota diversity on the skin, plus some anti-inflammatory benefits. The findings were published in the journal Environment International.

“One month of urban indoor gardening boosted the diversity of bacteria on the skin of the subjects and was associated with higher levels of anti-inflammatory cytokines in the blood,” Mika Saarenpää, doctoral researcher from the University of Helsinki’s Faculty of Biological and Environmental Sciences, said in a statement.

As Saarenpää explained, these benefits were found in a trial using a growing medium similar to soil found in a forest. 

But some participants were given a microbially poor soil made with peat, which is a common type of growing medium that has become controversial. That’s because harvesting peat means destroying peatland ecosystems, an important carbon sink, as reported by the International Union for Conservation of Nature (IUCN).

For the gardeners using a peat-based soil, there were no changes to skin microbiota or anti-inflammatory blood molecules.

Participants used flower boxes and store-bought peas, lettuces, beans, mustard, garlic and ginger plants (in a variety of forms, such as seeds, rhizomes and bulbs). Participants using the microbially rich soil experienced the benefits within only about a month of indoor gardening.

^{Gardening equipment provided for the participants consisted of a plastic planter, lamp, bulb, spray bottle, crop species and growing medium. Environment International}

The increased diversity in skin microbiota is important, as the researchers noted this can contribute to immunoregulation.

“We know that urbanisation leads to reduction of microbial exposure, changes in the human microbiota and an increase in the risk of immune-mediated diseases,” Saarenpää said. “This is the first time we can demonstrate that meaningful and natural human activity can increase the diversity of the microbiota of healthy adults and, at the same time, contribute to the regulation of the immune system.”

As a bonus, the indoor garden required little money or space to start, and many of the participants expressed interest in continuing with their gardens after the experiments ended, with some even planning to switch to outdoor gardening.

“We don’t yet know how long the changes observed in the skin microbiota and anti-inflammatory cytokines persist, but if gardening turns into a hobby, it can be assumed that the regulation of the immune system becomes increasingly continuous,” Saarenpää said.