This article maps out existing research regarding the effectiveness of subject-integrated school garden teaching. The school subjects of interest are mathematics, languages and science, and subject integration is defined as a link between these subjects and school garden teaching. The article is based on an integrative review and is derived from existing research, which claims that teaching in school gardens has a predominantly positive influence on students' academic learning outcome. However, experimental studies indicate that some programmes are less effective than more traditional teaching in the subjects concerned. The review extracts and discusses factors that are consistently regarded as vital to ensure the effectiveness of school garden teaching in terms of the integration of mathematics, languages and science. It is concluded that developing a school garden curriculum is essential with a view to planning, carrying out and evaluating subject-integrated school garden teaching. The teaching should include experiential learning and hands-on activities as teaching methods, making the subject content less abstract, stimulating the students' senses, and increasing the feeling of meaningfulness. Furthermore, collaboration across subjects and links between indoor and outdoor teaching are central factors in ensuring the effectiveness of subject-integrated school garden teaching.