Plants are crucial parts of ecosystems but are traditionally considered boring and difficult by students. It is therefore not clear whether factual knowledge about plants contributes to building positive attitudes and interest in botany. We investigated whether factual knowledge about monocotyledonous plants is associated with secondary students' attitudes toward and interest in plants. Furthermore, we examined whether self-reported plant cultivation experiences and gender differences exist in attitudes toward plants. Factual knowledge about monocotyledonous plants significantly correlated with attitudes toward plants and these attitudes were greatly influenced by interest in botany, ecology, evolution, and zoology, but not with other, more distant biological disciplines (e.g. microbiology, or health and nutrition). Females received better scores in knowledge and attitudes toward plants, but interest in plants was similar between males and females. We suggest that (1) factual knowledge in botany is essential in building positive attitudes toward plants and that (2) inter-connections between botany with zoology, ecology and evolution may help with elimination of plant blindness and building positive attitudes toward plants.