Wine Talk

Snooth User: Gantt Hickman

Hills vs Plains

Posted by Gantt Hickman, Feb 19, 2010.

Alright, I feel like I should know more about this already.

What differences will you see in wines that are grown on hillsides verses flat/field like vineyards?

I know that the amounts of sunlight play a role and the water runoff does as well.

I guess my question would revolve around this example: Northern Rhone has more flat land as where Southern Rhone has more hillside. What would these differences do to a Syrah grape?

Would the hillside not stress the grape as much those giving it a more fruit or earthy feel?

Thanks,
Gantt

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Reply by gregt, Feb 19, 2010.

As always, it depends, but I think you're making some assumptions that are not quite correct. Too much to really get into in a post but let's just look at a few basics.

Every grape needs a sufficient amount of sunlight and warmth to ripen. In the 1930s, professors at UC Davis came up with the concept of "growing degree days" or GDU, also called "degree days", "heat summation method", and the "Winkler Scale" after the professor who developed it.

The idea is that vines don't grow below 50 degrees F. So assuming that the growing season is April 1 to October 31, every DEGREE that a day averages over 50F is called a "degree day". It's a little tricky but if your temp is between say, 56 and 82 for a given 24 hours then your average for that day is 69 degrees. Since your base is 50, then that day is 19 degree days.

Add them all up by the end of the growing season, and you have the degree days for your region. They've categorized four regions, with 1 being the coolest and 4 being the warmest. Looking at the degree days of a particular region can clue you in to what you might expect, depending on what you plant.

So think about it. In Region 4, say Sardinia, you get olive oil and red wine. You move up north and past region 1 you get butter and beer because you can't grow grapes or olives there.

These regional bands correspond very roughly to 45 degrees latitude, at least in the northern hemisphere, but they are attenuated by a lot of other factors. Especially in the south, the band is much closer to the equator.

And that gives you your second important piece of information. It is not only the degree days themselves that you are interested in, but the distribution of those degree days. For example, in one year, the GDU of Walla Walla and St Helena might be very similar, even though Walla Walla is a few hundred miles north But in CA, the GDU will be evenly distributed across the season from April 1 to Oct 31, while in Walla Walla they may have a few extra hours of heat and sun each day in July, but a few hours fewer in April and September, since they're farther north. That's in fact one of the reasons for the difference in the ripening of grapes and the resulting wines from the two regions.

Now let's look at a few bands.
Region 1 = less than 2500 = hard to grow, includes some areas of Germany
Region 2 = 2500 - 3000 = early ripening varieties, Pinot Noir
Region 3 = 3000 - 3500 = may be best band for most wine
Region 4 = 3500 - 4000 = may be too warm for great wine other than exceptional places
Region 5 = eating grapes, not really good for most wine

And you want about 170 - 180 days for ripening.

The GDU varies by year too. In Washington, for example, they looked at some merlot grown around Walla Walla in 1999 and 2000. Growing degree days were lower in 2000 than in 1999, and measurement of total skin monomeric anthocyanin (TSMA) concentrations were therefore higher in 2000 than in 1999. That means less sun + less heat = darker, more tannic skins.

The south Russian River Valley ranged from 2,285 to more than 2,600 degree days between 2004 and 2006, part of Santa Barbara County ranged from 2,617 to 2,744. In addition, Santa Barbara gets a few extra days in November that they don't get farther north, so they're actually higher than these numbers suggest. St Helena on the other hand, can be over 3300, which is an entirely different category.

In 2006, Willamette Valley in Oregon had 2,400 degree days. Compare that to the average around Dijon, where it is 2000 - 2100. Other parts of Oregon however, and parts of Willamette, are comparable to Dijon.

The trade group Inter-Rhone reported that in 2007, which was very sunny, the northern Rhone was just under 2,800 degree days. More interestingly, Lyon, just outside the northern Rhone, averages around 2,300 degree days, while Beaune, in the Cote d'Or, comes in around 2,100 to 2,300.

The degree days trump hillside and soil content in terms of defining your wine. You can, however, further influence your grapes by the orientation of your rows. For example, in the Mosel, the grapes grow on slopes that capture the reflection of the sun on the river when the river makes east-west turns. That adds a degree or two to the temps and that is why they can actually ripen their grapes. If the grapes were planted on the other side of the river, they wouldn't ripen.

The North Rhone is as close to Burgundy as it is to some areas in the South Rhone. More importantly, the North receives cold air from the central mountains - the Mistral, which makes it a lot colder than the south Rhone. The south is protected from the Mistral by the hilly terrain. We see this influence of cold air in CA too, where Carneros gets cold air from the ocean that makes it a cooler area then places farther north.

Some people say that the most interesting wines come from grapes that are planted in the most marginal regions for that variety. That may be. Syrah is a wonderful grape because it expresses itself very differently and well in so many different areas. In hotter places, we get big, dark, inky wine, like some of the syrah from Sonoma and from Australia. In cooler places, it's actually a lot more like Pinot Noir. The syrah from Austria, north Rhone, Hungary, and even parts of the US, can be a lighter, less-overwhelming wine.

The issue of hills is more subtle. In places like Mendoza, the latitude would be too close to the equator and not suitable for vines. But because the vineyards are so high, they do not get overheated like they might if they were at sea level. In CA, it's different and less extreme. Some people say that the valley floor in Napa is too fertile and that the wines are better from the hillsides and particularly from those above the fog line. That's a debate that IMO comes down to personal taste. Unlike some people I don't believe that certain dirt means you're going to get X flavors in your wine.

I'm not 100 pct clear what you mean by "earthy", but as I use the term, it has nothing to do with whether the wine comes from hillside grapes. It has more to do with the winemaking style.

Cheers.


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