A bud breaks through at Benziger Winery, in Sonoma California
In the spring, the soil begins to warm, which causes water, organic acids, minerals and sugars to be pushed up through the vines. Buds that have remained dormant through the winter begin to sprout tiny shoots, which will in turn sprout leaves.
One of the biggest challenges for grape farmers comes during the early spring, when vines start to develop new buds. While the days are pleasant, nights can still get quite cold, and there's a possibility of frost to form, which can kill the newly-forming buds and ruin the chances for grape clusters to form and grow. One unlikely weapon against the nighttime frost of the spring is -- water.
Spraying the vines with water so ice forms on them actually helps to keep warm, as confusing as that may seem. When the water changes to ice, that physical conversion creates a tiny bit of heat, just enough to keep the vines from dropping below freezing temperatures. The sprinklers must remain on, because it's the change from water to ice that creates the warmth.
Other ways of keeping the vines toasty can include setting up heaters or wind circulators in the vineyard to keep cold air from settling on the vines.