I’d like to introduce you to an occurrence called shattering, an event that happens in the lifecycle of a vine that is often perceived as bad news but can instead be a factor of quality. I made a little video about it a few weeks ago while I was in a young Grenache vineyard (4th leaf) in our “Bellecoste” parcel. You can find it here.
Let’s begin with basic biology. The development of grapes starts, as all fruits, with the pollination of grape flowers. We call this period fruit set. Once pollinated, the grape berries begin to grow and develop. Unpollinated flowers abort and fall off the shoots – a process known as shattering. Ideally we like to have around 50% of the flowers shatter. Below you’ll find a comparison between two clusters of our young Grenache at slightly different stages.
So what causes shattering? Lots of factors impact shattering: examples are water stress prior to bloom, the nutriment balance of the soil, the vigor of the vine, etc… But the year-to-year variation in a vineyard is mostly due to weather: a spring frost, or cold, cloudy or wet weather will have a huge impact on any of the stages leading up to and including fruit set: flower budding, development, and bloom.
This year, I was a little concerned about the abundance of clusters on our Grenache (this is often the case after a hard winter). Happily, shattering not only eased the burden on the vines, but the clusters now have a nice load of berries, spaced out enough that they will remain loose through maturity. This will allow the free flow of air around the berries (a positive effect on their health) and the penetration of light (a positive impact on the berries’ coloration). The fact that the flowering of these Grenache took place during a rainy, cool period has been a way for mother nature to select the best … Now it’s up to us to treat them well!