The way in which most cities have grown, characterized by heavy air and water pollution, lack of green spaces, large energy consumption, unsustainable waste production, long distance industrialized food chains and an overall disproportionate footprint has led to a number of public health issues.1 As such, measures ensuring improved urban environmental management have become imperative.2

The importance of appropriate urban green spaces was formally recognized for the first time at European level in 1990, when the European Commission published the Green Paper on the Urban Environment.3 In this report the main environmental problems are pointed out and strategies outlined for the achievement of urban sustainability. Since then several agreements and documents (such as the United Nations’ Agenda 21, the Aalborg Commitments and the Leipzig Charter) have advanced social reflection, particularly with regard to urban sustainability –where the planning of attractive and multifunctional public spaces takes center stage.4,5

Nevertheless, despite some progress, the much sought after urban sustainability is far from guaranteed.6 Urban agriculture is one of the pieces in that puzzle that must not be underestimated, being a source of nearby healthy and diversified food.7 In addition, it doubles as a green zone, contributing to the broader environmental and social balance. Green spaces help regulate greenhouse gases, promote noise reduction, balance rainwater drainage (preventing floods), lessen the organic waste going to landfills, preserve soil and biodiversity, regulate the local temperature and even impart cultural and green values.8

On another level, local agriculture brings additional food security to urban deserts where poverty, economic crisis or social instability lead to hunger or at least little access to fresh fruits and vegetables. Self-production can make the difference between life and death. Organic urban gardens can also increase the availability of fresh and natural food. This increase could be beneficial to public health since it naturally favors its consumption.9,10

This type of agriculture also has a pedagogical role in enabling the urban population to make contact with the basis of its survival influencing its practitioners to a greater importance of preserving the environment like carrying out practices more environmental friendly.11

In short, urban gardening enhances both the human and the ecological dimensions of cities across the world.7 Recent projects across Europe are aiming at improving urban spaces by striking a balance between urban needs and sustainability, building bridges from food deserts to biodiversity through the green economy.12,13

Further, urban horticulture is a recent phenomenon in Portugal and its impact in different dimensions was not yet studied. In fact, this is the first study that aims to evaluate the impact of organic urban gardens in environmental practices and consumption of vegetables, fruit and organic food in the country. Research elsewhere shows promising results regarding the influence of urban gardens on several issues related with health, quality of life, education and environmental sustainability.14–20 Promising results in Portugal would contribute to the reinforcement of the role these structures play in public health decisions and to their expansion along the urban territory.

The objectives of this study were to characterize the environmental practices of participants of an urban organic community garden at the beginning of their gardening experience, as well as to evaluate the impacts of the gardening activity on those dimensions and on opinions towards organic food and fruit and vegetables consumption after a six-month involvement.

The present study suggests that the practice of urban organic community gardening is associated with improvement in personal environmental behaviors and overall environmental awareness. Participant's consumption of organic food and fruits and vegetables also showed improvement. Interestingly, extra gardening time was not associated with better outcomes for most of the angles considered.

The study was carried out in an urban organic community garden where the majority participants were professionally active, educated, middle-aged women. This specific profile can be understood through the criteria used for allocating plots, which gives priority to those working at the hospital on whose grounds the garden is located. This proximity allows for increased presence and gardening effort.

The questionnaire focused on environmental practices commonly available in cities (such as sorting domestic waste for recycling). This approach proved effective as remarkably positive changes could be measured. To the best of the authors’ knowledge this is the first time that urban gardening exposure has been shown to influence specific green practices of an adult sample.

Previous research suggests that “improving the environment” is a crucial aspect of participants towards horticultural activities, particularly as regards aesthetic and ecological values. Hence horticultural activities are beneficial not only for the participants but also for the environment.15 Our research goes one step further, uncovering the positive impact on specific environmental practices such as recycling and trying to have friends or family recycle, compost leftovers or choose to walk/bike to save gas. It's also important to note that the production of organic food in community gardens increases its consumption among participants, which can positively impact on health of the population and the environment, due to the reduction in the use of pesticides.

A correlation between an increased connection with nature by environmental volunteers and improved green practices, environmental awareness and responsibility was previously described in the literature. Participants reported that they had not incorporated these practices previously mostly because of “never really having thought about it”.22 Gardening being one way of (re)discovering nature, it is to be expected at least some level of influence. Our research shows the connection is in fact broad and encouraging. These results open new paths for public health since exposure to urban organic community gardens could boost citizen engagement in more environmental friendly practices.

From a public health perspective, it is equally noteworthy that research shows urban gardening seems to complement not just environmental education and conservation objectives but also health and wellbeing goals. The potential of urban and community biological gardens as an educational tool has been studied in children in a school environment and, similar to the present research, has registered positive results. Researchers have found an increase in consumption of fruits and vegetables as well as changes in behaviors and attitudes towards these foods in children exposed to gardening.14,23 Other studies have associated the practice of horticulture by children with improvements in social interaction with interesting results. Gardening could promote positive outcomes in social inclusion with respect to gender, social class, race and ability and improve self-understanding, interpersonal and cooperative skills.24,25 In addition, other studies have shown that children exposed to horticulture also improve their academic performance, exhibiting a more positive attitude towards learning and education.26 Despite the differences in sociodemographic profile, these results also point to the fact that exposure to urban community gardening is an excellent multilevel educational tool.

Adult samples also show encouraging results. Several studies have detected improved outcomes in physical activity, food and nutrition intake, mental and physical health, social skills, pain and smoking habits.16–20,27 In a world with so many physically and mentally debilitating chronic diseases, the active inclusion of organic gardens into urban planning could become part of the solution. The implications for public health are promising and profound. Urban organic gardens could provide availability and influence the consumption of healthy food, more green space in cities and be part of the answer to counter negative trends imposed by urbanization.

During our face to face interviews one dimension that emerged clearly was the constant exchange of knowledge among participants, who discussed among themselves the most diverse aspects of the trade –from the preparation of the soil to the productivity of each species and variety. The lack of prior gardening knowledge of the participants ended up promoting their socialization, in addition to the horizontal transfer of know-how and experience. Hence a new community is created that likely elevates the group's environmental awareness level through contamination. Further research should explore the actual dynamics.

Environmental awareness has proven to be one of the hallmarks of the horticultural experience. Recycling practices clearly showed improvement. Also, a drastic improvement in composting practices could be measured –a trend most likely prompted by the fact that a composter was made available for each plot free of charge. Solid waste management it's a big public health concern, in fact the by-products of an urban lifestyle are increasing even faster than urbanization.28 The last report from the World Bank Group says that world cities generate about 1.3 billion tons of solid waste/year and by the year 2025 this volume is expected to increase to 2.2 billion tonnes.28 The same happens with organic waste with an estimated volume of 38 billion metric tons produced worldwide.29 Since waste growth is an inevitable consequence of human urbanization there's a need to find solutions to counter such environmental and public health concerns. As we show in this investigation urban organic gardening could really be a big part of the answer by influencing recycling practices and given the opportunity to compost leftovers.

The influence of vegetable gardening on political optics and action could not be established as there were no elections in the year preceding the first evaluation. This parameter is not always easy to evaluate due to the time in between elections (usually 4 years). However social intervention (as in volunteering) was clearly improved. It is possible the horizontal transfer of knowledge among the garden colleagues encouraged such changes.

Some methodological aspects in this study contribute to data reliability. Both assessments were carried out during gardening appropriate months: the first during summer/early fall and the second at springtime. Also, there were very few losses: almost all gardeners initially registered were available at follow-up as well. And because the questionnaire was prepared specifically for this study (and there was a single researcher collecting data) the before and after comparison was made that much easier.

Nevertheless, the possibility that some of these results may be slanted due to information bias cannot be ruled out, since the participants, knowing the objectives of the study, may have tried to fit in with the researcher's expectations. In addition, the evaluation period was short. It could happen that the gardening commitment decreases in the long term, at least with some people. It should also be noted that the sample studied, because of its profile, is not necessarily representative of other community gardens. These characteristics will certainly influence levels of motivation, expectations and the ability to improve self-behaviors.

Study results reinforce the hypothesis that an organic community vegetable garden can induce significant positive behavioral changes among its users. In particular this research suggests horticulture is associated with positive improvements in personal environmental behaviors, awareness of the environment's high social priority and increased organic food, fruit and vegetables consumption.

Carlos Álvarez-Dardet.

The corresponding author on behalf of the other authors guarantee the accuracy, transparency and honesty of the data and information contained in the study, that no relevant information has been omitted and that all discrepancies between authors have been adequately resolved and described.

P. Nova: collection, analysis and interpretation of data; design and study conception; writing of the manuscript. E. Pinto: design and study conception; critical revision of the study and approval of the final version of the article; study coordination; writing of the manuscript. M. Silva: design and study conception; critical revision of the study and approval of the final version of the article; study coordination; writing of the manuscript. B. Chaves: critical revision of the study and approval of the final version of the article.

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