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Risks of winemaking grow in the cold
Extended cold weather can damage vines, especially the less-hardy European vinifera varietals. A few Colorado winemakers are considering adding cold-hardy hybrids to their vineyards.
Doug Neam looked at the merlot vines stretching across his property on East Orchard Mesa and pondered his good fortune when he stuck his first vines in the ground.
“I planted these in 1994 because I figured merlot was a varietal in demand and I knew it did pretty good over here,” said Neam. “That first crop was really good.”
Neam soon added to his merlot and a few years later expanded to a nearby south-facing slope where he planted cabernet sauvignon and cabernet franc.
Both the latter grapes also do well in the Grand Valley, although Neam, as are many western Colorado grape growers, is learning that not all vineyard property is equal.
Like many vineyards around the valley, Neam’s vines are spread across a rolling piece of land that falls off on either side. Such hillside vineyards are considered prime lands because the slopes shed the denser cold air.
Whether he did so intentionally or fortuitously, Neam planted his first merlot on a north-facing slope that falls off to a county road winding across the expansive mesa, providing an open alley of escape for the cold air.
Air flows like water, with the coldest settling to the lowest places, like cold water in a pond or your bathtub. Anglers know that the water issuing from a dam stays around 42 degrees year round, which means in the winter that water may be warmer than the surrounding air.
But it also means trapped air, which doesn’t freeze but may well below freezing, can kill tender vines, fruit trees and other plants.
Give that air or water an escape and it flows away, letting warmer air (water) take its place.
However, Neam planted cabernet sauvignon and cabernet franc where his land dead-ends at a neighbor’s brush-choked gully, a shrub dam that stops cold air and forces it back up to almost midway on the slope.
That stagnant lake of cold air, formed during the deepest freeze earlier this month, damaged the vines to where state viticulturist Horst Caspari warned Neam he likely won’t get a crop from those vines in 2013.
“You’ve probably lost everything on that low end of the vineyard,” Caspari said during a recent visit to Neam’s vineyard. “You can see where the cold air pools and it’s like there’s a line where your vines are dead.
“Above that line, you’ll probably get some grapes.”
This cold-weather line of demarcation is a phenomenon that Caspari finds all-too-often across Orchard Mesa where the best agricultural lands often are bordered by dense jungles of growth.
Those ravines, gullies and watercourses are key to proper air drainage, and their existence is part of the reason for the many different micro-climates on Orchard Mesa and East Orchard Mesa.
On a recent tour of cold-struck vineyards from 32 Road to Palisade, Caspari time and again pointed to low spots where vines have been blackened by cold air stopped by wildland growth.
“You can almost see a circle of dead vines where the cold air sits,” he said at one stop, waving his arm to delineate an imaginary high-water line of cold air pooled along the low end of a vineyard. “I’m sure they lost everything in that circle, and the obvious thing would be to put a wind machine right there, to keep that air moving.
“But do you see any machines around here? Not one.”
Neam is fortunate, for he still has some open, south-facing acreage to plant more vines where the gentle, unclogged slope promises better air drainage.
Other landowners, particularly those late arrivals to grape growing, are not so lucky.
“I always recommend they come talk to me before they plant their vines but often that doesn’t happen,” said state enologist Steve Menke during last week’s VinCo conference sponsored by the Colorado Association of Viticulturists and Enologists and the Western Colorado Horticulture Society.
“Too many times, someone walks into my office and says, “I planted five acres of merlot but they aren’t doing very well. Can you help me?’”
Menke shrugged.
“If they had come to us before they planted, I could have helped them with site selection,” he said. “Now, I have to tell them they spent a lot of money on a site where grapes won’t grow.”
Cold spell poses big problems for grape growers and 2013 vintage
State viticulturist Horst Caspari points to where cold air pools and kills grape vines in an vineyard on East Orchard Mesa near Palisade, Colo.
EAST ORCHARD MESA – The thump of wind machines waking you last week wasn’t a dream but an attempt by grape growers to ward off the vine-killing cold.
However, it’s been grape-deathly cold in some spots for several weeks and grape growers tardy in cranking up the 30-foot high wind turbines may be too late to prevent losing part or all of next year’s crop, warned state viticulturist Horst Caspari at the Western Colorado Research Center on East Orchard Mesa.
“We have a maximum on cold-hardiness our grapes can reach and if we get below that, it’s done,” he said. “But if you have a wind machine to use and you don’t use it under the conditions we have now, we haven’t learned anything from 2009.”
That was the winter when a December deep freeze sent the temperature in western parts of the valley plunging to 22 below zero and more than 50 percent of the vines in the valley suffered extensive damage, with many growers losing most of their 2010 crop.
Temperatures this year have flirted with that low mark – a minus 18 was registered recently near Fruita – but along with temperature growers also must consider wind speed and length of exposure to the cold, Caspari said.
A few minutes at 28 degrees won’t bother most grape buds but longer exposures at the temperature can kill them as surely as 18-below.
As grapes and other fruit go dormant, their cold-resistance increases. But once the plants reach their most-dormant, temperatures below that may kill or damage the bud or vines.
Wind machines mix warmer air from 100 feet or more with frigid ground-level air trapped by inversions or pooling behind physical dams such as building or trees.
Fans may only bring a rise of 3 or 4 degrees, but that can be sufficient to save a crop.
The easternmost part of the valley benefits from a year-round breeze from DeBeque Canyon. The breeze acts as a natural wind machine, keeping that part of the valley warmer by not allowing the cold air to pool.
The cold air certainly gathers along the Colorado River, where pockets of air can be minus 8 or 10 when it’s minus 1 on East Orchard Mesa, where the cold air flows off the north-sloping fields and lands along the river.
“We didn’t run our machines (Sunday) night but we did the three previous nights,” said Galen Wallace, vineyard manager for Plum Creek Cellars’ vines on East Orchard Mesa, well above the coldest layers of air.
Still, there are enough microclimates in the gullies and ravines that monitoring the temperature is “huge in this business,” Wallace said. “We get 10 percent (bud) damage at 5-below so I watch it closely and when it gets to 1-below I’m ready” to start the wind machines.
Surprisingly, the valley’s largest grape grower hasn’t yet run his wind machines.
“No, we haven’t run our machines yet and that’s probably a mistake,” said Bruce Talbot, who farms 150 acres of grapes and 300 acres of peaches across Orchard Mesa and East Orchard Mesa.
“The peaches are just fine but we know the grapes are sensitive right now,” Talbott said. “We were told the grapes can take 10 below and if we get close to that we can sustain damage, so we try to minimize that.
“But so far, minus 2 and minus 4 are what we’ve seen in town.”
Caspari said that temperature might be misleading, since it probably measures temperate at cordon height (about 40 inches) and not at ground level, which could be several degrees colder.
“So it’s four degrees colder at snow level and where some of his vines are might be 5 degrees colder than the weather site, so that’s minus 4 and another 5, that’s 9 degrees, so it’s really 13 below right above the snow line,” Caspari estimated. “Bye, bye, it’s toast.”
More on cold and grapes next week.
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