In the face of growing global hunger, sustainable agricultural practices are becoming important. Localised agriculture community knowledge is essential to guide these practices. Online communities can overcome some barriers of physical communities for knowledge sharing. However, studies to understand factors related to online-agricultural-communities’ growth for knowledge sharing are lacking. To address this gap, we studied five Facebook-based online agriculture communities over one and half years, recording monthly member numbers and some community characteristics by analysing the content. Through data analysis, we found that the separation of the community as knowledge creators (exists only to give) and knowledge consumers (exists only to take as per knowledge creators' thinking) hinders the growth of online knowledge-sharing agriculture communities. We discovered communities that have grown shared the following characteristics: informal, interactive, bidirectional, simple, and clear information flow patterns guided by explicit, clear, and simple norms and purpose without authoritative separation of community.