Wheat adaptation can be fine-tuned by Eps genes. Although the effects of Eps genes are often assumed to act independently of the environment, previous studies have shown they exhibit temperature-sensitivity. Number of leaves and phyllochron are considered determinants of flowering time and the numerical components of yield include spikelets per spike and fertile floret number within spikelets. We studied the dynamics of leaf, spikelet and floret development in near isogenic lines with either late or early alleles of Eps-D1 under seven temperature regimes. Leaf appearance dynamics were modulated by temperature, and Eps alleles had a greater effect on the period from flag leaf to heading than phyllochron. In addition, the effects of the Eps alleles on spikelets per spike were minor, and more related to spikelet plastochron than the duration of the early reproductive phase. However, fertile floret number was affected by the interaction between Eps alleles and temperature. So, at 9ºC Eps-early alleles had more fertile florets than Eps-late alleles, at intermediate temperatures there was no significant difference, and at 18ºC (the highest temperature) the effect was reversed with lines carrying the late allele producing more fertile florets. These effects were mediated through changes in floret survival, there were no clear effects on the maximum number of floret primordia.