This month we are watching our vines grow...literally, and we're watching them very carefully too. For this is the time of the year when the tender new canes and lush new leaves develop rapidly, and the vines prepare for that most important time event of the season, bloom. As you read this blog the vine's floral buds will have fully formed, and by the end of May the buds will have "blown their tops." Actually, this is exactly what happens. The floral bud has a cap, called the "corolla," which when the bud is mature pops off to allow the petals of the tiny vine flowers to unfold. One the vine is in bloom, pollination takes place over a period of approximately ten days. Grapes are hermaphroditic, or self-pollinating. The flower's male stamen discharges pollen into the air, usually during the early hours of the morning, which is captured by the female pistil. The pollen then moves by gravity into the ovary where germination takes place. Because the floral clusters of the vine are so delicate, during the period of bloom we hope for very good weather: no rain, extremes of temperature, or high winds, any of which can adversely affect pollination and thus the new important event we call "set."
So far this spring, we have been enjoying mild weather. According to Tuesdays Sonoma Index Tribune, our year-to-date rainfall is 10.36 inches. (The rainfall year is calculated from October 1st to September 30th.) At this point in 2020, we had received 14.02 inches of rain. We are already more than twenty five percent behind last year. Honestly, we are starting to get worried and are planning for a drought year in the vineyards.
Our vines, incidentally, look very good this year with lots of healthy growth. Their foliage also is quite dense, which we like to see because the vine's leave are where photosynthesis takes place. This is Mother Nature's way of converting sunlight to carbohydrates which nourish both the vine and its fruit. Carbohydrates not needed during this season will in the fall be stored in the vine's root system to sustain it thought the winter, and of course the more carbohydrate reserve, the stronger and more vigorous the vine will be next spring.