Outdoor educational programmes are generally believed to be a suitable alternative to conventional biology settings that improve participants' environmental attitudes and knowledge. Here we examine whether outdoor educational programmes focused solely on practical work with plants influence participants' knowledge of and attitudes towards plants. It was found that mean scores of participants' attitudes towards and knowledge of plants significantly increased after the outdoor programme. These effects remained significant even after three months' post-testing. No similar patterns were found in the control group. Interestingly, the proportion of participants who liked biology as a school subject also significantly increased after the outdoor programme in the experimental group. Females showed better knowledge of plants than males, but attitudes towards plants were similar between genders. Having a garden at home was not associated with better knowledge or attitudes towards plants. Our results reveal that outdoor programmes significantly relieve "plant blindness" and make biology more attractive to pupils. (Contains 1 table and 1 figure.)