This is the most important time in the whole vineyard cycle, and this is certainly when all the cards come into play.
When temperatures in late spring and early summer exceed 15 or 16 degrees, floral caps are released to show their stamens and pistil, waiting to be fertilized and the resulting set.
These stages are very influenced by external climatic factors. The ideal conditions for this process is more effective with an average temperature of 21ºC, dry weather and light wind; instead of unfavorable temperatures (below 15ºC and rain).
Unfavorable causes can mean fertilization does not happen or an irregular set is produced, giving what is called cluster falling.