Maize is the most important cash crop in Vietnam's northern mountainous region. It is credited with eradicating hunger and alleviating poverty. However, the continuous decreasing trend in the global maize price since 2013 has resulted in various socioeconomic problems. Yen Chau district follows a cultivation regime of annually changing maize varieties. This goes against the objectives of national test procedures for new seed. This study aimed to establish whether the annually changing seed cultivation regime is the consequence of the fierce competition between seed enterprises. We found that the maize trading structure is centered on a three-level trader network that plays a crucial role in connecting stakeholders. Strong social relationships along with weak credit/production commitments between farmers and traders have facilitated maize production throughout the region. Seed and supply enterprises target traders to promote their products and are the most important information channel for farmers. This study's findings suggest that seed selection in Yen Chau has no scientific basis but is the result of market factors.