Springtime in the Vineyard

A month ago, I visited the vineyards in Santa Barbara county, and brought you up to date on how budbreak was going in the vineyard. Now we are into full Spring weather conditions, and moving into the cycle of the grapevine life: flowering. Unlike the beautiful blooming dogwood trees we have in my community, the flowering of grapevines isn't really a colorful event, and would probably be missed by most people driving by the vineyards.

Those tiny little embryo bunches we started to see last month are beginning to open, and little green flowers are sprouting. This usually occurs, on average, about eight to ten weeks after budbreak, so the early ripening varieties are flowering before the later ripening vines (which are still in budbreak). See my article on the noble grapes to see how different grape varieties progress in the vineyard.

Just as in the previous cycle, flowering is a very critical time in the vineyard (probably the most critical), and the eventual bottle of wine. Flowering involves pollination and fertilization, so the future grape harvest is dependent on ideal conditions. The weather needs to be frost free and dry. Rain and freezing temperatures can damage the fragile flowers. An ideal daily temperature would be above 60 degrees. This is where vine position is important. Those vines that are positioned to gather more sunlight will have a better chance of producing healthy fruit down the road. Since Spring days are warm, and nights are still cool, the warming of the soil plays a significant role in vine development.

Since frost is still a real hazard this time of year (and one of the greatest threats to the vintage), many vineyards are protected by aspiration systems (sprinklers), smudge pots (heaters), or wind machines (which help circulate the cold air, which will settle low, and around the vines).

"Flower of the grape vine; Anticuous Anthers."-Whitney, 1902
Earlier, I mentioned the pollination and fertilization of the flowers, which will eventually become hard little clusters of green berries in the fruit set stage (about 6 to 8 weeks after flowering). I'm sure we all remember our high school biology classes...yeah right! Well, one thing you'll remember is the pistil and stamen discussion, and how male and female plants produce fruit. In the case of wine grapes, we do not need male and female plants. Wine grapes are hermaphroditic (also known as "perfect"), meaning they are self pollinating.

It is during the flowering stage, that the vines can be affected by a condition known as "coulure". Coulure is caused by wet, cool weather. The flowers remain closed, and do not fertilize. When this occurs, the berries will not develop properly, and the fruit will drop. Another condition is known as "millerandage". It is similar to coulure, in that weather conditions affect the potential grape bunches. The bunches will produce uneven grape size and different levels of grape maturity. Ultimately this affects the harvest, and the eventual income of the grower. Again, a critical time in the vineyard.

By understanding the different cycles of the life of the grapevine, you understand how the vintage might be affected.  Appreciating all the different stages, and decisions that go into your bottle of wine, helps explain the regional characteristics. So enjoy your glass of wine, and keep watching the weather.

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