Since the 1992 United Nations Conference on Environment and Development (UNCED) in Rio de Janeiro, there has been international recognition that a change towards sustainable development requires a thorough change in awareness at all levels (UNCED, 1992, p. 329 f.). This conference marked the beginning of the official promotion of Education for Sustainable Development (ESD). In this study, we define ESD as a holistic, problem-solving, future-, and action-oriented approach. ESD addresses social, ecological, and economic aspects of different themes of sustainability and the local and global perspectives on these themes, the latter of which is particularly important in this research (Amariei et al., 2016, p. 3; Rieckmann, 2012, 2018; Scheunpflug, 2001, p. 87; Schreiber & Siege, 2016, p. 84). ESD responds to the global challenges that can be tackled through a new way of learning and teaching (Barth & Rieckmann, 2008; Scheunpflug, 2001, p. 87) and offers a significant contribution to the transformation of our society (Amariei et al., 2016, p. 3).

A core aim of ESD is to link local action with global thinking. This is exemplified in Virtual School Garden Exchanges (VSGE), which link local gardening initiatives in schools globally through virtual exchanges.

Virtual exchange ‘is a practice (…) that consists of sustained, technology-enabled, people-to-people education programmes or activities in which constructive communication and interaction takes place between individuals or groups who are geographically separated and/or from different cultural backgrounds, with the support of educators or facilitators’ (Evolve, 2018). VSGE is a special form of virtual exchanges: In a VSGE, learners from primary or secondary schools around the world who are engaged in school gardening can communicate in the virtual world about their garden experiences and related topics using media such as emails, photos, films, or video conferences.

The combination of virtual exchanges and school gardens is a relatively recent innovative development. To provide an overview of this area of research, to ‘describe and explain current knowledge’ (Fink, 2014, p. 7) and to identify gaps, we conducted a systematic literature review. We quantitatively and qualitatively analyzed a sample of 158 peer-reviewed articles on school gardening. As a direct search using VSGE and synonyms as search terms did not provide any results, we chose to approach it from three directions: the integration of the global perspective of ESD, the use of digital media, and the international exchanges/ partnerships in school gardens. As VSGE is embedded in the research landscape of school gardens, this was the starting point and focus of the systematic literature review. We addressed and responded the following research questions:

Which developments in school garden work have been documented in the scientific literature since 1992 regarding…

a)      …the embedding of the global perspective of ESD in school gardens?

b)      …the use of digital media in school gardens?

c)       …the establishment of international exchanges/partnerships between school gardens?

Has VSGE or a similar approach been analyzed in the scientific discourse on school gardening since 1992?

Our systematic literature review was inspired by Barth and Rieckmann’s (2015) research design and followed the systematic review approach outlined by Fink (2014). Our aim was to provide a systematic and replicable search and analysis strategy that was fully documented and transparent. Going through the steps of data collection, data processing and coding, and data analysis, we produced a bibliometric overview that combines quantitative analysis with qualitative content analysis. The literature search was conducted in two databases: Scopus and ERIC (Education Resource Information Centre). Using the following search terms: ('School garden' OR 'Learning garden' OR 'garden-based education'), the search produced 440 hits. The hits were screened using predefined criteria. 158 peer-reviewed paper formed the sample, their bibliometric variables were analyzed statistically. Based on the autocoding of the MAXQDA function 'MAXDictio', the frequency of the search items was analyzed. This was complemented by an analysis of word frequency within the keywords. Based on the quantitative analysis, 14 articles were identified as relevant for addressing the research questions. Then a qualitative content analysis of the selected articles was performed in accordance with Mayring (2000).

The systematic literature review provided us with a picture of school gardens as a diverse and heterogeneous field of research. We used three different angles to determine whether VSGE or a similar approach had been described in any of the articles. The first angle, regarding the embedding of the global perspective of ESD in school gardens, yielded eight articles. They provide examples of an integration of the global perspective of ESD into the school garden in the form of content, multicultural learning, the garden design, and school garden exchanges. The second angle refers to the use of digital media in school gardens and provides insights into different uses of digital media (e.g., photos, online courses, applications, blogs, sensors, video conferences) for teaching, documentation or reflection, providing information, monitoring of gardens and plants, and interacting with plants or other people. The use of digital media to communicate with other people described in five papers is particularly interesting because it is a core element of VSGE. For the third angle, we analyzed articles regarding international exchanges or partnerships between schools. The VSGE concept is described in only a single article but before the exchange actually took place. Our systematic literature review highlighted that no publications– at least not fulfilling our conditions – have been published on the experiences gathered during the implementation of VSGE.

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