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A report: The impact of frigid weather on our state's grape crop
While the entire state is reeling from this Arctic blast, winegrowers across Ohio are literally praying for their 2014 crop and that their very vines survive these next couple of days. Grapes are generally considered 'tender' crops and are especially sensitive to low winter temperatures. Based on a release from Dave Scurlock of OARDC [the state viticultural outreach specialist]
the key factors involved in all of this concern are the actual low temperatures recorded. Although strong wines can desiccate the buds as well as vine structures and cause some damage, the real fear comes from the sub-zero thermometer recordings. Fierce winds in relation to cold temps do damage by drying out cell structures to exasperate damage. [Dave notes that wind chill, as we traditionally think of it, is much more critical to warm blooded animals thus plants.]
We have not seen these lows for many years and they will especially test our viniferas. Hopefully, it will not be bad as 1994 when the Wooster station recorded a -28 degrees actual temperature in their demonstration vineyards.  | | Pinot Gris bunch from the 2013 growing season |
If temperatures drop much below -10 or 15 degrees, we'll see significant 2014 damage among the Cabernets, Chardonnays, Pinot Noirs and Pinot Gris. Up to 90% of the buds can be destroyed below those readings. Rieslings and French Hybrids are less sensitive, but they too will likely see damage in the 50% range.
A greater fear is that if the frigid temperatures remain -- or return again in the winter for an extended time. Then actual vine damage [or even death] will occur. In January of 1994, when temperatures remained significantly below zero for fourteen days, many vineyards faced major replanting schedules....along the the loss of 3 or more years of production until the new vines were ready to harvest.
In the twenty years since that long stretch of bitter cold, our growers have learned a lot. They have become more selective about the sites where their most tender varieties were planted, have added every-row tiling to drain excessive water which was identified as a culprit during those two frozen weeks, and added wind machines which, on a still night can mix the layers of air and raise vineyard floor temperatures several degrees [not much help with 30 MPH windy nights however.]
Dave's alert to the growers included suggestions to delay in any additional pruning for a while, to leave as many buds as possible, to wait til the coldest snap passes and do random bud cuts to check for dead tissue and then assess their pruning plans.
In the meantime, growers will be biting fingernails and quietly petitioning the weather 'gods' for a quick return to more normal conditions. | 
Ohio Wine Producers Assn