Grape Varieties for Cold Climates
Part I of two about short-season viticulture in cool to cold climates
There is a commonly held belief among wine lovers that the more delicate wines demonstrating a terroir effect are grown in cool wine regions such as Germany, Burgundy and Austria. Pinot Noir and Riesling wines are often noted for their amazing capacity to highlight the nuances of site.
With new viticulture technology in the form of cold-hardy and disease-resistant hybrid grape varieties, the possibility of growing fine wines has expanded into cool and cold areas that were previously thought to be inaccessible to wine production. Ontario has a phenomenal 12,000 acres of vinifera vineyards. The Minnesota Grape Growers Association annual meeting regularly attracts more than 500 participants. Anywhere there are people who like to drink wine, there are folks who want to grow it, whether it really makes sense or not.
Extension educators like me try to have answers for their growers. During a recent trip to the Endless Mountains in northeast Pennsylvania, I found myself shrugging my shoulders so much they got sore. That’s not a good feeling. Between the effects of climate change, growing grapes on the threshold of survival, the availability of new hybrid varieties for which little is known about best cultural practices and yet another bizarre growing season, it’s very hard to explain everything that is happening in the vineyard. The growers I encounter always have many questions, and unfortunately I have few answers for them.
Vineyards, as a general rule, are filled with conundrums and compromises. At Sugar Hollow Vineyard, winegrower Paul Milnes wondered about the relative necessity of hilling up, which creates serious erosion channels on his hillside site. Do you protect the vine or the soil? Another question asked was: With vineyard soils saturated from heavy rains and tractor access limited, should the cover crop be mowed for frost avoidance?
Defining cool and cold
Cool and cold can be defined as a cool growing season that limits fruit ripening and a cold winter that threatens the vines with winter injury. In this relationship, cool areas may not necessarily be cold, but cold areas are always cool. But when does warm turn to cool and cool become cold?
I’m not sure the differences can be exactly quantified. The growing degree-day system seems inadequate to the task. Some benchmarks may offer hints: Germany, Champagne, Burgundy and northwest Spain are cool; Bordeaux, Piedmont and Tuscany are warm; parts of southern France, southern Italy and Spain are warm to hot. In between these seasons is the danger of frost in the spring and fall.
None of these regions has the regular risk of winter injury that exists above the Mason-Dixon line. Frost and freeze injury are often induced by similar climate, site and viticultural conditions. They also are avoided using strategies such as avoiding low spots where cold air pools and causes damage and excess soil moisture can delay proper vine acclimation. I’ll use frost and freeze interchangeably throughout this article, although they are physiologically very different events to the vine.
People often ask me what effect climate change is having on vineyards in Pennsylvania. My unscientific perspective tells me that we are having longer frost seasons and more dramatic frost events like the Easter freeze in 2007. Seasons and weather events appear to be more extreme, such as the difference between 2009 and 2010 vintages. All of this further complicates the challenge of growing grapes in areas with marginal climate characteristics.
In cool/cold wine regions there are two primary viticultural goals: to get fruit to full maturity so it can make the best possible wine, and to have the vines survive the winter so they have a chance to make wine. We begin with the elemental truth that the best wines are made from fully mature grapes—this is truest for reds but also applicable to whites. Thoughtful planning, expert viticulture and a lot of luck are necessary to achieve consistently high-quality wines under these conditions.
It begins by making every effort to compress the vegetati ve cycle of the vine, which increases the chances that the fruit will fully ripen and, hopefully, be less exposed to harvest hazards such as rain, frost, birds, bunch rots, etc. Fortunately, all of the design and viticulture that promotes fruit ripening also enhances cold hardiness in vines, such as creating a balanced vine, not over-cropping, removing crop with enough time before the first hard frost for the wood to achieve maximum cold hardiness, etc.
In most cases I would argue for a balanced vine of small to medium size to achieve these objectives. Smaller vines carry less fruit and tend to ripen their grapes earlier than bigger vines with more substantial crops. High-density winegrowing in Germany, Austria, Burgundy, Champagne and Ontario seems to bear out this truth, but with little evidence of any impact on cold hardiness.
Matching variety to climate
Cool- and cold-climate viticulture is all about matching variety to climate. In order to do so, accurate knowledge of the climate of the vineyard site is needed. Thirty-year climate data can be interpolated from weather stations to give an accurate account of the climate history of a property almost anywhere. The key variables are length of growing season from the last spring frost to the first fall frost, growing degree-days and low winter temperature where it is a threat to vine health and survival.
Since everything is done in the service of the wine, knowing what type and style of wine the grapes are intended to make is essential. A $10 bottle of Concord has a very different requirement than a $25 Riesling. Once climate and wine are identified, a process of risk assessment must occur. Cool/cold viticulture is always on the razor’s edge, and it never takes much to push a vintage into the gutter. To be quite frank, the easiest and most prudent vineyard decision is to plant varieties that are fully adaptable to the local climate conditions—those that will survive the winter and ripen in the fall.
Many new growers want to make classic European wines, even at great peril. Most do not fully comprehend the dangers those vines will face and the extra effort and expense that will be necessary for them to thrive if, in fact, that is a possibility. For the risk averse, the traditional and new cold-hardy hybrids are the wise and safe choice. Their names are not easily recognizable to the consumers, but they can make very high-quality wines. During the planning process, consider the effects of climatic hazards on quality, economics and the sustainability of the vineyard.
If at all possible, find other growers in your area who understand the local climate conditions. Unless you are in a well-developed vineyard region like the Niagara Peninsula, North Fork of Long Island or the Finger Lakes, you may not be able to find a nearby grapegrower, so look for a crusty orchard grower who has an intimate understanding of the local conditions and can tell you every frost event in the past 50 years. This kind of information, while anecdotal, can be extremely valuable. There are also excellent viticulture consultants that can help you determine the climate conditions of your site and assist you with the assignment of proper varieties, vineyard design, prevention strategies, etc.
I have a general belief that as a wine consumer I would almost always prefer a ripe hybrid wine to an unripe vinifera wine. In many areas where both are planted, winegrowers and consumers are confronted with this choice. Cold-hardy hybrid varieties developed at Cornell University, the University of Minnesota or by adventurous and talented grape breeders such as Elmer Swenson of Wisconsin usually have a shorter growing season and are more disease resistant, in addition to their cold hardiness.
As a group, the new hybrid varieties—especially the red wines—have a tendency towards high to very high acidity and often some level of what I describe as a “grapey” or native flavor—anywhere from overt to subtle. At the University of Minnesota, Peter Hemstad is breeding red varieties away from high acid and toward more vinifera-like character, Marquette being the most recent and notable example. The technology keeps improving, and who knows if we will eventually have a dead ringer for Cabernet Sauvignon that ripens in 120 days and withstands temperatures of -30°F and colder.
The cold, hard truth is that cool/cold areas are best suited for white wine production for a variety of reasons. Whites generally ripen earlier, and they are more forgiving, flexible and adaptable to make a good wine from a wider range of maturity than reds.
Many white varieties such as Grüner Veltliner make very different styles of wine at low to higher Brix levels, but both whites and reds are attractive and have their supporters. Of the reds, only Pinot Noir is a classic international variety that is suitable for cool climates, and even then it is extremely fickle and challenging to make consistently high-quality wines. However, other red varieties such Zweigelt, Blaufränkisch (Lemberger) or even Dornfelder can make interesting if not charming wines—reds that say “hug me.”
At Nimble Hill Vineyards in Tunkhannock, Pa., I tasted a basic red wine made from a blend of St. Croix and Cabernet Franc and declared it the perfect entry red wine with just a touch of sweetness that says “hug me” to the consumer. In Nova Scotia I asked why the wineries insist on making red wines, and they told me frankly that at least half of the people who come to the winery want red wines. OK, but let’s forget about snobby reds and go for the crowd pleasers.
On that note I was told that the secret to the balance of a friendly red was blending a portion of California-grown wine (what I refer to as “sunny” wine) that helped to fill in the middle and give the wine a lift. It made the wine complete. As long as there is truth in labeling and adherence to the local wine laws, I think winemakers should use blending as a tool to make wines better—especially red wines. Most winemakers now know that a portion of ripe Merlot or Cabernet Franc can improve almost any Frontenac or Marquette.
However, the focus of any cool/cold wine region should be on white wines such as Riesling, Gewürztraminer, Pinot Gris, Chardonnay, Grüner Veltliner, Albariño and the legion of hybrids. Chardonnay is troublesome because of its early bud break, and no one really knows how cold-hardy varieties like Albariñ ;o and many other exotic aromatic vinifera white varieties really are. Some growers have told me that Sauvignon Blanc is very hardy, and others say it is very tender.
As a rule, cold hardiness in any variety is very hard to pin down and fluctuates from one winter to the next, although generalizations abound. I am always scratching my head about the relative hardiness of Merlot vs. Cabernet Sauvignon. One thing we know for sure is that among the Bordeaux red varieties, Cabernet Franc is the most hardy, and it has become the default classic vinifera red wine in regions like the Finger Lakes and Niagara Peninsula largely due to its cold hardiness. But can it really make consistently good wines, and is it worth the effort to try to find out?
Returning to white varieties, the cold-hardy hybrids such as La Crescent, Frontenac Gris, Louise Swenson, Prairie Star and others offer viticultural and wine features that make them outstanding choices in almost any cool to cold climate. Nor should the traditional hybrids such as Vidal, Seyval, Traminette, Maréchal Foch, Baco Noir and others be ignored since they are very viable wine candidates. Vidal, in particular, is a variety that has great wine potential—from unctuous ice wines in Ontario to zesty, dry white wines on the New England coast.
Some areas have hybrids particular to their own region that make them unique and interesting such as Quebec with Michurinetz and Vandal Cliche, and Nova Scotia with L’Acadie, Lucie Kuhlmann, Cabernet or Marechal Foch. Whether these varieties will ever receive wider recognition for their wine prowess is another matter, but on a local and regional level they have tremendous ability to please and sustain a winery enterprise.
The necessities of the marketplace cannot be ignored either. Who are the customers, and what wines will they buy? There is no sense making a wine if no one wants it. Market and viticultural realities are often at odds and must somehow find a balance. In frost- and freeze-prone areas, grape sourcing is a key ingredient to winery survival. Winemakers in Pennsylvania agree almost unanimously that most customers in our tasting rooms care little about the origin of grapes. I believe this is mostly a rural phenomenon. People just want a wine that tastes good to them. The more sophisticated (city) wine consumer will eventually demand a local source of grapes, but that moment has not yet arrived. It is up to each winery owner to decide how and where to source their raw materials. I prefer a strict emphasis on local sources with outside materials used only as a blending tool to fill in gaps in a wine profile.
Part II of this article will address problems with cold-climate grapegrowing.
Mark L. Chien is statewide viticulture extension educator for the Penn State Cooperative Extension based in Lancaster, Penn.
|E-MAIL THIS ARTICLE|