Vineyard Bloom

Full bloom in our vineyard - median bloom time for our grape varieties - is usually close to June 1st but it’s later this year. Bloom barely started June 7th and is now nearly finished on June 15th. LaCrosse, Petite Pearl and Melody will finish bloom by the end of this week. Why is Bloom later this year?

So, what is Bloom? Bloom is the flowering stage of growing grapes, and it has the potential to form the berries on the grape clusters. Blooms emerge on the newly formed flowerets on each shoot which are self-pollenating, so they don’t depend on bees or other pollinators. The flowerets are made up of calyptra – structures that look like teeny, tiny, green closed tulips flowers and contain both male and female parts. The calyptra shed and push out anthers that pollenates the ovary inside it.

Why is Bloom late? The timing of bloom depends on the location of the vineyard, the temperature, wind, and the amount of Spring rainfall. This is the seventeenth year of growing hybrid grapes in our vineyard, and we figure our unusual rainy May with over 8 inches of rain and cooler than normal temperatures pushed bloom later by at least a week.

How does a late Bloom impact the grape crop? We don’t know for sure yet. It could have a negative effect on the fruit set, or it could push back our usual harvest dates. Or, it could have no impact if fruit set is good and the weather helps vine growth catch up. Early indications are that the fruit set is quite good. So what happens between now and harvest depends on the weather for the rest of the growing season.

We’re not making any weather predictions, especially in the age of climate change. That’s crop farming for you. Fingers crossed!