End Of Frost Season
June is really busy here. We began by ending frost protection for the season. Frost protection has two components. One is easy and one is labor intensive.
The easy part is setting the cold air drain machine to “automatic start” in March after the vines are pruned. The machine is the large green structure in the accompanying photos.
Frost forms from the ground up. As the freezing air accumulates on the ground, gravity moves it to the lowest spot in the vineyard. That’s where the electric machine sits permanently. The machine has a digital thermometer 10 inches above the ground. When it registers 34 degrees, the electric machine starts automatically. That means its 7 foot diameter fan begins spinning parallel to the ground.
It draws the cold air from the ground and exhausts it high into the air. If the machine exhausts the freezing air before it rises to the level of the spring buds on the cordons (about 30 inches above the ground) we have no frost damage.
The machine ran successfully 6 nights this year. It typically starts around 2 am and stops automatically around 8 am when the attached thermometer registers 39 degrees.
The labor intensive part is removing the frost tarps. In the accompanying photos Gerry is removing 1 of the 20 frost tarps he hung in March. Each tarp is 8 feet high and 30 feet long. Our vineyard sits just below the peak of Howell Mountain. The tarps prevent the freezing air accumulating above our vineyard from moving into our vineyard.
The accompanying photos show the tarps hanging the length and width of our vineyard.
We wait until early June to end frost protection because we had devastating frost damage in 3 of the past 6 years. One of those frosts was in late April and the other two were in late May.
Positioning and Topping the Canes
Each cane gets tucked through 2 sets of training wires each spring. The canes can grow more than 8 feet tall. In the accompanying photos you can see Barbara completing the tucking and positioning.
We want each cane to stand as straight as possible. The grape clusters grow on the canes. If the canes are standing straight, the grape clusters have more space between them which enhances development and even ripening. We position the canes to grow straight by putting plastic ties around or between them and attaching the ties to the training wires.
After the canes are positioned, they are topped. Topping is accomplished by cutting each cane by hand at about 5 feet above the cordon. That height retains enough leaves to ripen the grapes while minimizing the canopy the canes form if they are not topped. The canopy formed by the canes falling over the training wires would shade the grapes from the sun and inhibit ripening.
Barbara is working in a row before it was topped. The accompanying photo shows the same row after the canes were positioned and topped. This is not a task we can complete by ourselves in the necessary time frame. Our vineyard manager’s 13 man crew completed the positioning and topping in 2 days.