With record-breaking temperatures expected this weekend, our thoughts turned to our budding grapes in the vineyard. Four years ago we had high temps later in the growing season (read more here). What about now? If we were going to have a heat event, says Director of Viticulture Ray Nuclo, this is probably the best possible time.
Two weeks earlier and the heat would have been detrimental to fruit set. In another month or so, when the fruit is softer and ripening, high heat could put the grapes at risk of sunburn and water stress. Right now, the biggest concern is keeping workers safe and out of the worst heat of the day. Shifts start early and wrap up by 2:30 p.m.
Work in the vineyards now is focused on leaf pulling to thin the canopy and allow for better air flow and proper sun exposure. This work becomes even more critical during high heat. As leaves are removed, care must be taken to not expose the ripening grapes to too much sun before the berries have had a chance to adapt to direct exposure. Grapes that develop in sunlight after early leaf removal can better resist sunburn. (Just like people, the berries can handle more sun after a little exposure.)
Typically we experience one or two heat snaps in the summer, although this one looks to be record breaking. The hottest temps Ray recalls seeing in his 23 years in the Willamette Valley is 107 degrees. Still, the grapes can take a heat spike, especially at this point in the growing cycle. Rainfall earlier in June helped by replenishing the moisture in the soil. With the heat, moisture is lost faster through a process called evaportranspiration (a biological process by which plants lose water through their leaves in order to grow – we are excited to get to use that term!). King Estate is dry farmed, or not irrigated, so we are counting on having enough water stored in the soil to make it through the growing season.