Grapevines Have Flowers? You Betcha.
By: Mackenzie Brisbois
It’s not a bouquet I’d like to receive but grapevines do have flowers and they do smell wonderful. A vine produces about 1-4 flower cluster per shoot. The inflorescence (flower cluster) develops opposite a leaf on a shoot and usually develops at nodes 3 and 4 and nodes 6 and 7. How fruitful a plant will be is determined in the season previous and is affected by factors like light, water, temperature and nutrition.
We refer to this period as bloom or flowering because the individual florets start to open. In PEC flowering starts sometime around the middle to end of June (about 8 to 10 weeks after budbreak). It usually lasts about 7 to 10 days. The calyptra starts drying up and triggers a rupture of the anthers so pollen gets released onto the stigma – eh Voila. Grapes!
Factors Affecting Pollination
The weather conditions need to be just right to get perfect fruit set. Flowers open fastest around 20 to 25°C and they like dry and warm conditions. Cold, rainy or windy conditions can reduce the percentage of flowers fertilized. This year we had lots of ‘chickens and hens’ in certain varieties This means we see lots of small and big berries resulting from uneven fruit set. Riesling always seems to produce a lot of big and small berries, but this year I saw it in some of the Chardonnay as well. Each variety flowers at slightly different times so weather conditions can change quite a bit. I don’t mind chickens and hens so much because it means a bit looser cluster with more airflow – meaning a bit better protection against disease. It does mean slightly less of a crop. Since our flowering wasn’t overly windy or rainy, I think it might actually have been too hot! Regardless of the less-than-perfect fruit set the actual fruit out there still looks good. We are still on track for one of our best vintages yet at Trail Estate.
But please, no more rain dances for a few weeks!