Seed germination is the process by which an organism grows from a seed. It requires suitable conditions and environmental factors. Maize is one of the most important crops worldwide. Germination influences both final maize yield and quality. Seed germination is regulated by a complex gene network. It is also influenced by endogenous (phytohormones and nutrients) and exogenous (temperature and water) inputs, involving molecular networks only partly identified to date. This review describes current understanding of the influence of temperature, water, phytohormones, and nutrients in regulating maize seed germination, and indicates knowledge gaps that should be addressed.