The paper analyzes the emergence of transformative agency and the evolution of a new concept of integrated pest management in a Change Laboratory intervention among Finnish greenhouse tomato growers fighting whiteflies that challenge their traditional individualist modes of working. Transformative agency was analyzed with the help of six types of discursive manifestations, ranging from resisting and criticizing to envisioning and taking actions to change the situation. The data consists of 13 h 28 min discourse recorded in the six Change Laboratory sessions. 947 expressions of transformative agency were identified and analyzed. The germ cell of the new concept was found to reside at the intersection of the agroecological and social systems. By way of criticizing the current activity and by explicating unacknowledged potentials in the activity, year-round growers defined the new concept of activity. This concept was not unanimously accepted by seasonal growers whose pest levels were already lower. The analysis shows, however, that both parties accepted the systemic nature of the problem and expressed willingness to change practices that perpetuate the systemic problem. The study suggests that concept formation requires a series of actions taken by the practitioners to change their own activity.