Grape growers watching weather as final ripening nears
The basil is gone, the tomatoes are drooping and there’s a bit of hope (but fading fast) for the last of the chard. That’s just in my garden. Thank goodness I don’t have acres of grapes to worry about.
But worry they will, as grape growers are wont to do, as they watch and wait for what’s remaining in the 2011 harvest to get as ripe as possible before picking.
“We’re about half-finished,” said Nancy Janes of Whitewater Hill Vineyards on a recent sunny Sunday afternoon. “We’re about half done with the varieties but less than half done with the volume.”
Which tells an astute listener (or at least one with a good memory) that Janes and other Grand Valley grape growers are feeling the effects of the three late-spring frosts that killed some of this year’s crop as well the lingering aftermath of the December 2009 deep freeze.
Some of the varietals, such as syrah and merlot, haven’t yet recovered from that 2009 setback while others — among them cabernet sauvignon, cabernet franc and riesling — are further along. Now, add the cold spell from last week, when some locales marked temperatures dipping into the high 20s, and you have the perfect mix to keep growers and winemakers awake at night.
Who said this was going to be easy?
“You can see some of the damage and how scattered it is,” said grower Neal Guard, climbing down from the tractor he was negotiating between the rows of vines on his farm on East Orchard Mesa. He grabbed a handful of grape leaves, brown and crackly in the sun. “These are toast, but right next to them the vines are untouched,” he marveled. “It shows how unevenly the cold settles into a vineyard.”
While the cold didn’t last long enough or drop deep enough to do a lot of damage, Guard still ran his wind machine a couple of mornings to keep the air circulating.
“It was 30 right about here,” he said, his hand about 8 inches off the ground. “But at the top of the machine (30 feet up) it was 35 or so. I wanted to mix that air so I didn’t get those cold pockets.”
Growers are closely watching the progress of such late-ripeners as cabernet sauvignon, cabernet franc and riesling, waiting for sugar levels to reach optimum, or if lucky, as high as demanded by the winemakers. Grapes need temperatures above 50 degrees to produce sugars and ripen, and when the temperature barely edges above 50, the grapes are slow to ripen further.
But frosts kill leaves, and once the leaves are gone, photosynthesis stops and the grapes start to dehydrate, which calls for instant response from the grower.
“That’s when you start making those 2 a.m. phone calls to get people out to pick the grapes,” Guard said. Preferably, the grapes ripen while the leaves still are producing nutrients, because the leaves produce the energy the vine stores to survive the winter.
Janes, echoing comments from growers contacted during the Colorado Mountain Winefest, said her grapes were a bit behind after the cool and rainy July but have rebounded thanks to the warm September. “It really was just what we needed,” Janes said, eyeing the rows of blue-black grapes hanging plump and sweet in the bright October sun. “Now, if it holds on for just another week, everything will be fine.”