Meaningful discussion that facilitates reflective thinking can be initiated when learners raise thoughtful questions or provide critical feedback; however, generating effective questions requires a certain level of domain knowledge and meta-cognitive skills of the question-askers. We propose a peer-questioning scaffolding framework intended to facilitate meta-cognition and learning through scaffolding effective peer-questioning in online discussion. This framework assumes that novice students who lack domain and meta-cognitive knowledge can be scaffolded to generate meaningful interactions at an early stage of learning and the resulting peer-generated adaptive questions can facilitate learners' meta-cognition. Thus, this study investigated the effects of providing online scaffolding for generating adaptive questions to peers during online small group discussion. A field experimental time-series control-group design was employed as a mixed model for the research design. Thirty-nine college students from an online introductory class on turf grass management participated in the study. The findings revealed that the scaffolds were useful to increase the frequency of student questioning behavior during online discussion. For some students, the online guidance reportedly served as "a starting point" to generate questions when they had difficulty asking questions. However, the guidance did not improve the quality of questions and thus learning outcomes. The interview data indicated that peer-generated adaptive questions served a critical role in facilitating learner's reflection and knowledge reconstruction. Further study should focus on the quality improvement of peer-generated questions while considering adaptive and dynamic forms of scaffolding and intermediate factors such as prior knowledge, meta-cognition, task complexity, and scaffolding type.