While I was on the 5:30am flight out of Eugene, Oregon Friday morning, Bob and Nathan were in the vineyard stoking our first Frost Fire of the season. I had known when I left for the airport a few hours earlier that it was going to be a frosty morning and I hoped the guys would be ready to do battle and that all of our preparations would pay off.
Thursday had been devoted to frost preps. Bob hung the plastic curtain on the deer fence along the upper perimeter of the vineyard while Nathan and Nick mowed down the grass within the fence, all thirteen acres of it. We cut the grass to maximize as much as possible the distance between any frost that would form on the ground and the green shoots on the vines. It’s a proven strategy for minimizing frost damage in vineyards.
The plastic curtain is an experiment, an idea Bob had to prevent the warmer air we circulate through the vines by burning fires and running a fan from escaping out of the vineyard. The vines in the ten or so rows along the fence are furthest from the fires and have suffered frost damage in past years, even on nights when we were up burning.
I am very excited to report that based on the results Friday morning, the frost curtain appears to be working! Bob and Nathan started the stump fire and the fan at 4:30am, about the time I was going through security at the airport. The outside temperature was down to 34F and had been dropping by about one degree per hour throughout the night. By dawn, it was just 30F outside of the curtain. But on the other side of the curtain in the vineyard, the temperature never dipped below 32F. And in the warmer parts of the vineyard, closer to the fire and fan, the temperature held at 34F.
This is the first empirical evidence we have that our frost fighting strategies are making a difference! The fire and the fan are definitely warming the air not just in the immediate vicinity of the fire, but throughout the vineyard. And the frost curtain is holding that warmer air in the vineyard to protect the vines.
This is a tremendous relief as our vines continue to leaf out. If you look closely at the above photo, you will see a bumpy nub starting to emerge from the top of the shoot. That’s the inflorescence, or flower pod that will produce the grapes. In the coming weeks the inflorescence will swell, and then little white flowers will appear. When the flowers fall off, little green berries will grow in their place to create a grape cluster. So there it is already in the tip of that shoot, our 2014 harvest and wine. That is, unless we let it freeze.
Of course, the best protection against frost in the vineyard is fog. When an overnight fog rolls in, it forms an insulating blanket over the entire vineyard that slows the temperature drop from the daytime highs. The past two mornings have been foggy and haven’t dropped below 34F, so no fires since Friday. But as I sit here now, the sun is out and there’s not a cloud in the sky. So we’ll be getting up throughout the night tonight to check the temperatures and look for fog.
Meantime, the dogs say it’s a beautiful day for a romp in the vineyard. And, I have horses to groom. But not until after this DET STL hockey game. If St. Louis loses, and it looks like they will, The Colorado Avalanche will finish the season as the top team in the Central Division! Woot!! (Little known fact, the five blocks of vines in the vineyard are named for the five former Avalanche players whose numbers have been retired. It was an idea we had while planting, as an homage to the team we had to leave behind in Denver).