Integrating Horticulture into 21st-Century Urban Landscapes

1. Introduction

Urbanization has long been recognized as a significant challenge to achieving sustainable urban development [1]. One of its key impacts is the reduction in green spaces per capita, driving the need for innovative approaches to integrating green infrastructure into cities. Urban horticulture, encompassing practices such as community and allotment gardening, vertical and rooftop greening, and similar strategies, has emerged as a promising solution [2,3]. This trend reflects an inevitable shift toward nature, with increasing interest in designing urban gardens that incorporate edible ornamental and utilitarian plants. Given the limited space in urban areas, there is a growing emphasis on combining esthetic appeal with utility, necessitating creative approaches to urban gardening. However, urban gardening and fruit cultivation face notable challenges. Space constraints require the use of compact tree forms, such as dwarf, columnar, or narrow-pyramidal shapes, often grown in containers. These adaptations are typically achieved through genetic mutations affecting growth habits or by grafting onto low-vigor rootstocks. Additionally, the proximity of urban gardens to residences restricts the use of conventional pesticides, highlighting the importance of disease- and pest-resistant varieties or biopesticide usage [4].

According to the available literature, interest in the narrow ‘urban horticulture’ topic among researchers grew significantly, from initial low numbers in the range of 0–8 in the period 2001–2009, to 4–17 in 2010–2018, and finally to 15–24 in 2019–2023, as can be noted from Figure 1. Although alterations are present, there are specific peaks in publication frequency that followed two major ISHS conferences ‘II International Conference on Landscape and Urban Horticulture’ [5] (held in 2009 and published in 2010) and ‘International Symposium on Urban and Peri-Urban Horticulture in The Century of Cities: Lessons, Challenges, Opportunities’ [6] (held in 2010 and published in 2014). Those conferences attracted 182 and 41 papers in total, respectively, but not all of them listed ‘urban horticulture’ as the main topic. Nevertheless, noted interest and peaks can be understood in a broader time-span and associated with crises that humanity faced in the early 21st century. As stated by Calvet-Mir et al. [7], urban gardening in central and northern Europe, as well as North America, attracted significant academic attention, with the influence of the economic crisis of 2007–2008 present but not fully understood, urging future investigations. The prominent peak of 15 publications in 2010 reflects this raised interest, since the previous nine years only yielded 23 publications in total. The next peak appeared in 2014, reflecting results from efforts in crisis recovery in several different countries throughout Europe, most recently evaluated for Spain [8], Greece [9], Slovenia [10], and Portugal [11].

Finally, the period 2019–2023 steadily resulted in 15–25 publications annually, which can be associated with the ‘XXXI International Horticultural Congress, IHC2022: International Symposium on Urban Horticulture for Sustainable Food Security (URBANFOOD2022)’ [12] as well as the COVID-19 crisis. The COVID-19 pandemic has profoundly affected the availability of sustainable fresh food, causing significant disruptions to both supply chains and market prices. In response, urban horticulture and crop cultivation have gained prominence as viable strategies for extending food production into new spaces by leveraging urban green infrastructure [13,14,15,16]. The available literature on ‘urban horticulture’ suggests that this field achieved its maturity in 2023, when publications were mainly associated with scientific journals [17,18,19,20] rather than conference proceedings.

This topic is also valued for its contribution towards long-awaited resilience. When observed and established in a sustainable manner, urban horticulture contributes to multiple Sustainable Development Goals, providing numerous ecosystem services.

Table 1. Connection between Sustainable Development Goals and sustainable urban horticulture.

SDG	Contribution Examples	Reference
No poverty	Reduced purchasing	[21,22]
Zero hunger	Food production	[21,23]
Good health and well-being	Superfood, organic concept	[22,24]
Quality education	Public educational gardens	[21,25]
Gender equality	Women’s self-employment	[21,26]
Industry, innovation, and infrastructure	Green infrastructure increase	[21,27]
Reduced inequalities	No gender, race, or age restrictions	[27,28]
Sustainable cities and communities	Environmental resilience/Waste recycling practices	[21]
Responsible consumption and production	Short food supply chain	[29,30]
Climate action	Greenery climate adaptation	[21,31]
Life on land	Wildlife habitat and feed	[21,32]
Partnerships for the goals	Intertwined mutually	[21,33]

presents urban horticulture’s alignment with SDGs regardless of type (direct/indirect), strength (low, medium, or strong), or effectiveness (short-, medium-, or long-term).

From the Guest Editor’s point of view, thanks to the experience created for more than a decade in urban agriculture, in a broader sense, urban horticulture can meet SDGs through social, environmental, and economic benefits. Their own ornamental and/or edible gardening and food production provides income-generating opportunities for urban farmers and small-scale entrepreneurs through the sale of fruits, vegetables, flowers, and other horticultural products, concomitantly reducing household expenses by enabling self-sufficiency in food production (SDG1). Furthermore, this kind of activity diversifies diets and improves access to fresh, nutritious food for urban populations, especially in food-insecure areas, in difficult times like economic and health crises (SDG2). Individual or collective urban gardening encourages physical activity through required managing practices and promotes mental health by connecting people mutually and with nature (SDG3). Joining efforts with academia, NGOs, or relevant enterprises, urban gardening serves as a hands-on learning platform in schools and communities, teaching skills related to horticulture, nutrition, and sustainability (SDG4). Teaching and education further fortifies gender equality, involving school-aged girls, women, and elderly people, providing them with economic opportunities, and giving them a voice in household and community decision-making (SDG5). All these listed benefits can be regarded as directly social since their main contribution is oriented towards the improvement of quality of life.

Sustainable urban food production encourages the use of rainwater harvesting, water recycling, and efficient irrigation techniques with minimal inputs (SDG6), and is coupled with the use of renewable energy sources like solar pumps for irrigation and energy-efficient greenhouse operations (SDG7). Such an approach creates new jobs and supports employment in urban farming, plant nurseries, and related sectors like food processing and distribution, encouraging eco-friendly and small-scale entrepreneurship (SDG8). All these are prerequisites for SDG9, where the integration of green spaces into urban planning contributes to smart city initiatives, increasing areas under vertical farming, rooftop gardening, and hydroponic/aeroponic/aquaponic technologies.

In relation to SDG5, urban horticulture fortifies gender equality, and aligning with SDG10, it provides economic and nutritional benefits to marginalized communities in urban and peri-urban settings, calls for community engagement, and strengthens social cohesion through community gardening initiatives. Taken all together, urban horticulture thus increases urban resilience to food crises by localizing food production and contributes toward sustainable cities and communities (SDG11), since edible green spaces enhance urban biodiversity and wildlife, concomitantly mitigating urban heat islands and improving air, soil, and water quality. Such bonding with nature-based principles supports awareness-raising towards waste reduction, promoting the recycling of organic waste into compost, closing the loop in food production, encouraging the sustainable consumption of seasonal, local produce, and shortening the food supply chain, leading to zero miles transportation (SDG12).

If conducted on integrated and organic principles, urban horticulture can positively impact SDG13-15, by acting as a carbon sink that reduces greenhouse gasses, as a runoff controller of fertilizers and pesticides including organic fertilizers and biopesticides, preventing waterway contamination, and as a biodiversity promoter by providing habitats for pollinators and other species.

Although with a weaker influence on SDG16, food and overall plant production (individual or collective, public or private) creates shared spaces for collaboration, reducing social tensions and fostering community harmony, all while involving citizens in urban planning and decision-making processes. And finally this partnership between people and nature, people and Government, people and industry, as well as people and people, supports the achievement of SDG 17, ‘Partnerships for the goals’.

2. Overview of Published Articles

Urban residents perceive urban food production from different points of view; thus, Narandžić et al. (contribution 1) investigated basic requirements for gardening practicing, the public awareness of urban horticulture, and the attitudes toward the design of urban gardens. Questionnaire responses revealed significant differences between the two periods regarding respondents’ attitudes toward the impact of urban horticulture on food security, socialization, and personal health and development, before and after the COVID-19 pandemic. Most respondents grew vegetables, typically in household yards and gardens. The primary motivations for engaging in community urban gardens were growing food for personal consumption and making charitable contributions, followed by the desire to socialize and relax. To raise awareness and gardening habits, the study presented several exemplary designs for an urban pocket, kindergarten yard, and atrium courtyard, offering valuable insights into various landscaping possibilities and providing an exhausting list of various species for edible landscaping purposes.

Furthermore, Kafle et al. (contribution 2) tackled the economic viability of practicing urban agriculture. With the critical assessment of the sustainable urban agriculture (UA) viability, this study examined three common UA practices (vacant lot, backyard/rooftop, and discretionary labor) under the assumption that UA has expanded to the point where competitive market rates must be paid for land, labor, and the distribution of produce. The study compared these dynamics within the contrasting developmental contexts of Adelaide, South Australia, and Kathmandu Valley, Nepal, to understand how local economic and infrastructural conditions influence the feasibility of scaling up urban agriculture. The analysis revealed that the economic viability of UA is primarily driven by the profitability of specific practices, with crop selection playing a critical role in determining the potential for sustainable income. Thus, choosing the right crops is essential for the long-term success of UA in urban settings. Ideally, UA should serve as a local food production system that contributes to food security by providing competitively priced food compared to traditional market rates.

Focusing on a more specific and narrow topic, Elshaer et al. (contribution 3) provided insight into how sustainable gardening practices (SGPs) in hotels influence the prediction of tourists’ intention to revisit, with tourist attitudes toward green hotels serving as an indicator. Additionally, it explored the role of environmental gardening identity (EGID) as a moderator in this relationship. Results from 286 respondents suggested that, due to heightened environmental awareness, customers assess green practices based on their authentic altruism toward the environment, and that sustainable gardening practices positively and significantly enhance tourist revisit intentions.

No matter the scale and character of the green space, plant material seems to play a crucial role in the establishment and success of edible urban landscapes, fitting the space and meeting expectations. In this regard, Istrate et al. (contribution 4) investigated the organic production of numerous vegetable species and cultivars in raised beds formed in home gardens. This study provided useful recommendations on optimizing crop production, nutritional value, and sustainable gardening practices, mentioning some limitations and the need for future research to evaluate the effects of different bed heights on the performances and edibility of various plant species.

While the mentioned study investigated different vegetable species and their compositions, three studies focused on only one major fruit crop (apple), followed by two studies focused on one true ‘edible ornamental’ (rose). Unlike conventional apple production, urban-related growing needs to be adjusted to organic principles. With this aim, Vlad et al. (contribution 5) presented a detailed life cycle cost assessment, indicating that the main costs are related to the use of agricultural machinery, certain pesticides and insecticides, anti-hail nets, plastic boxes, and labor costs, accompanied by transport and storage additional costs, all of which are completely avoided when apple is produced in the nearest proximity for immediate consumption by residents. In the next study, Vlad et al. (contribution 6) provided insight into preferences of apple consumption in Romania, indicating the significant influence of age, consumers’ education, and specific regions’ dependence on choosing Romanian over imported apples. According to Iordănescu et al. (contribution 7), urban apple production in Romania can rely on the old varieties ‘Domnesc’, ‘Mustoase’, ‘Pătul’, ‘Jonathan de Munte’, and ‘Botu Oii’ due to their taste and appearance, which are improved by grafting and size reduction. In particular, the ‘Botu Oii’ variety achieved low vigor, strong resistance to diseases and pests, large tasty fruits, and an attractive appearance, meeting the requirements of urban gardening. Furthermore, the disease- and pest-resistant varieties ‘Jonathan de Munte’ and ‘Pătul’ can be valuable edible landscaping elements.

Observed from the same perspective, six new edible rose genotypes were examined as functional food sources, suitable for both urban and rural gardening. Specifically, Simin et al. (contribution 8) conducted research on the morphological and chemical properties of ‘Olivera Frayla’, ‘Lavender Vaza’ ‘Pear’, ‘Eveline Wild’, ‘Theo Clevers’, and ‘Marija Frayla’ roses. With a pronounced number of flowering shoots, double red purple flowers, a large number of petals, the highest level of total phenolic compounds, and the strongest antioxidant activity, the ‘Marija Frayla’ cultivar can be promoted for the production of novel functional food products and dietary supplements, while all six cultivars can contribute to urban food production. When considering urban food delivery from roses, emphasis can also be placed on the feed. Notable amounts of pollen/nectar production and pollinator attraction were noted in another group of rose genotypes, investigated by Božanić-Tanjga et al. (contribution 9). This study concluded that due to the esthetic appearance, disease tolerance, and pollinator visitations, ‘Mella’ roses ‘Barbie’, ‘Ruby’, ‘Ducat’, and ‘Exotic’ can be an element of semi-natural urban gardens/landscapes that deliver important ecosystem services to both humans and wildlife.

A critical issue surrounding urban gardening is the safety of its produce, particularly given the heightened health risks associated with urban horticulture. Unlike rural cultivation, crops grown in urban environments are frequently subjected to elevated pollutant levels, raising concerns about their suitability for consumption. A significant contribution to this Special Issue is thus the study on heavy metals in lychee fruit samples carried out by AL-Huqail et al. (contribution 10). Even though heavy metal concentrations (with the following trend: Pb < Cd < Zn < Cu < Ni < Fe < Cr < Mn) in lychee fruit samples remained within acceptable limits, the findings revealed that samples collected from urban and industrial areas exhibited higher levels of heavy metals compared to those from agricultural or rural regions, urging further studies on different locations and fruit species exposed to pollutants.

3. Concluding Remarks and Future Prospects

Urban horticulture is no longer a niche activity but a crucial component of 21st-century urban sustainability. By transforming vacant urban spaces, rooftops, and walls into productive green areas, urban horticulture has the potential to enhance food systems, foster community resilience, and promote healthier, greener cities. By coining this philosophy and practice as ‘horticulturalization’, as well as launching a Special Issue with the same term, the intention was to call for urban horticulture implementation, integrating it into urban planning as well as everyday life. Since urban areas are projected to house over two-thirds of the global population by 2050, urban horticulture might emerge as a vital strategy for sustainable development. Its integration into urban landscapes provides not only economic and nutritional benefits but also environmental and psychological advantages. It bridges the gap between cities and nature, reducing the ecological footprint of urban living while improving quality of life for residents.

The future of urban horticulture depends on its inclusion in urban planning as a mainstream element rather than a historically present element. Green roofs, vertical gardens, allotments, and community farms should become standard features in modern cities, contributing to food systems and ecosystem services.

Planners, landscape architects, and infrastructure engineers should collaborate with horticulturists to design multi-functional urban spaces that combine esthetics, productivity, and sustainability. Rapidly developing high-tech vertical farms, rooftop greenhouses, and edible urban forests can transform cities into self-reliant ecosystems that mitigate the urban heat island effect, improve air quality, and enhance residents’ well-being.

By prioritizing urban horticulture, cities can support the circular economy and evolve into regenerative ecosystems that not only sustain human life but also restore natural systems. The integration of horticulture into urban landscapes offers a vision of cities that are not only places to live and work but also places to thrive in harmony with nature. This transformation will define sustainable urban living in the 21st century.