Early flowering is a survival strategy in wheat ( Triticum aestivum L.) that sacrifices grain yield under long photoperiod conditions, and this contradiction is greatly affected by floral growth and development. However, little is known about the regulatory mechanisms that remove the barrier between “early flowering” and “high yielding” during floret development. Here, we showed high-resolution analyses of the number and morphology of floret primordia and the transcriptomes of wheat spikes in three light regimens. The development of all floret primordia in a spike could be divided into four distinct stages: differentiation (Stage I), differentiation and morphology development concurrently (Stage II), morphology development (Stage III), and polarization (Stage IV). Compared to the controls, the long photoperiod supplemented with red light treatment shortened the time required to complete Stage I-II, then improved assimilates in the spike and promoted anther development, thereby increasing fertile floret primordia during Stage III, and maintained fertile floret primordia development during Stage IV until they became fertile florets (grains) via a dynamic gene network centered on ubiquitin, calcium signaling, aldehyde dehydrogenase, zinc finger proteins, and heat shock proteins. Our findings proposed a light regimen, critical stages, and candidate regulators that promoted early flowering and high yield in wheat.