Definition - What does Nouaison mean?
Nouaison is the French term for the initial phase when small grapes begin to form after the flowers have been fertilized. This is the time of "fruit set". This stage occurs almost immediately following flowering. It is a critical stage for wine production and determines potential crop yield. Not every flower will get fertilized.
WineFrog explains Nouaison
A fertilized flower will soon develop the grapes in order to protect the seed which is formed. At the time of nuoaison, the grapes are about the size of a peppercorn.
The health of a vine and the climate are two important factors which play a role in the percentage of flowers fertilized. Lower humidity also helps. The average amount of flowers which are fertilized are around thirty percent, but can be as high as sixty percent.