Garden-based learning settings can reveal a profound interplay of global citizenship education (GCED) and scientific literacy. The implementation of Agency in the Anthropocene in the PISA 2025 Science Framework has made this ground even more fertile. It can be cultivated when science topics are developed within language and cultural contexts. Content and language integrated learning (CLIL) nurtures prerequisites for language acquisition as well as deep content comprehension. The respective conditions do not have to be artificially constructed, but organically arise from the experiences and activities inherent to garden settings. For language learning, active engagement, opportunities for autonomy, and the authentic learning environment fostered by the scientific work play pivotal roles. Deep content comprehension can result from merely noticing and talking about linguistic phenomena: language(s) can enhance comprehension by addressing the challenges posed by overlapping terminology and concepts in everyday and specialized contexts. Language investigation can bridge comprehension gaps, as learners navigate diverse linguistic landscapes that reveal new perspectives and interpretations. Examples from the classroom and international student projects demonstrate that the integration of languages and cultures provides a fertile ground for a profound exploration of concepts through multiple lenses, creating the conditions necessary to achieve the goals of sustainable GCED.