Do young children think that plants deserve morally-based respect or, on the contrary, do they feel that respect for plant life is nothing more than another behavioural norm similar to, for instance, one that states that you should not pick your nose in public? This study examines how dilemmas involving environmental, moral and socio-conventional situations are comprehended in early childhood so as to investigate the issue of whether young children attach a significant degree of severity to transgressions against plant life in comparison with disregarding socially accepted rules. Additionally, young children’s judgements are put into perspective alongside their understanding of the concept of living things in order to shed light on the role that grasping essential biological notions might play in the emergence of young children’s assessments of actions that pose a threat to the environment. The sample of the study consists of 328 children (162 girls and 166 boys) who attend Early Years Education or Primary Education and the data examined comes from the individual interviews conducted with the children. The results are discussed in connection with the current understanding of the source of ethical judgements which emphasises the importance that emotions seem to play in the construction of moral thinking.