Demystifying Terroir with Steve Matthiasson

Steve Matthiasson talks terroir at Texas Wine School.

Steve Matthiasson of Matthiasson Wines was the speaker at the Houston Sommelier Association on Wednesday at Art of Cellaring. He brought five single vineyard Napa Valley Cabernet Sauvignon barrel samples from the 2021 vintage to taste and discuss with Houston wine professionals. "There's a lot of mystery in terroir," stated Matthiasson, "but it's not random, it's the differences in the land."

Napa Valley's proximity to the cold Pacific Ocean allows for many vineyard areas to enjoy the moderating affects of cool breezes and fog coming through which lower temperatures, some areas are heavily influenced by this terroir aspect, Steve explained, while others are not. 

The majority of the year, water temperatures stay in the lower 50s (degree Fahrenheit) cooling the surrounding air which pushes into the Napa Valley through the Carneros AVA in the south. This is caused by the Great Pacific Upwelling which causes the deep, cold water to rise to the surface. Sea breezes brings these cooler temperatures inland. Temperatures rise from an average daily temperature of 80 degrees Fahrenheit in the south to an average of 95 degrees up valley in the northern town of St Helena. The exception is northern Calistoga which receives its own cooling influence through the Chalk Hill Gap. The surrounding mountains play a role in temperature as well. The eastern facing vineyards on the Mayacamas side of the valley are typically cooler than the western facing vineyards on the Vaca Range. The valley AVAs all enjoy cool nights.

Millions of years of plate tectonics, volcanic activity, and earthquakes formed the land from the mountain ranges and the valley to the diverse soils. Much of Napa Valley has volcanic soils, igneous and lava gravel in the mountains, colluvial soils that have been washed down the hillsides, and alluvial fans between the hillsides and the valley. The valley floor has been influenced by the movement of the Napa River over time, this has created alluvial soils filled with rock and gravel in some areas and deep sandy loam in others. Matthiasson discussed how all of these elements affect mineral levels in the soil which then affects the vigor of vine growth and the ripening of the grapes.

The Vaca range has young, rocky volcanic soil with poor water retention causing the vines to struggle, it also has one of the warmer micro climates, the grapes sourced from this area display thicker skins with more tannin. Howell Mountain has higher potassium levels in the soil which leads to lower acid wines with a higher Ph. Diamond Mountain has similar potassium levels but it gets cooler at night which creates a softer wine. Mount Veeder creates structured wines with red fruit and more pyrazine.  Oak Knoll has more marine soil that is lower in potassium which creates more acidity and brightness while across the valley is where Matthiasson says one finds more volcanic soil with more magnesium and higher water retention that gives more of a cranberry character or flavor to the Cabernet Sauvignon grown there.

Matthiasson also spoke about how "spring conditions define the vintage." More stress in the vines creates more tannin as part of the vine's immune system to defend the fruit from pests, worms, and fungi. Tannin is developing before the vines bloom to protect the flower clusters. The character of the vintage is decided while the vines are making the fruit and how much the vines are struggling for water during that time. Drought years have a bigger structure than rainy years. However, the quality of the vintage can still be degraded in the fall from excessive rainfall, hail, or too cold or too hot temperatures that affect the final ripening.

Matthiasson acknowledges that despite the terroir differences, he believes that "all the barrel samples still taste like Matthiasson Wine because that's where the 'people aspect' of terroir comes in." He harvests each plot at different times to get what he believes is the perfect balance of flavor ripeness, acidity, and tannins.

The Barrel Samples:

Circa Vineyard - Located in the heart of the Rutherford AVA, this vineyard has well-drained soils but only moderate water stress. The area has average potassium levels creating structured wines with a dark fruit and dried leaves mid-palate mouth coating character. Matthiasson stated, "It tastes like a Napa Valley wine." He expects it to be about 20% of his blended Napa Cabernet in the future.

Dead Fred Vineyard - Fred was the cat of the owners of this Coombsville AVA vineyard and he is dead (from natural causes) and buried out there. The soils in this vineyard are comparable to the soils on Howell Mountain with a few differences. It is primarily volcanic rock but it is a bit cooler than most of Napa.  Matthiasson described the wine from this area has having a fresh, crunchy red fruit character that is reminiscent of Syrah. Matthiasson said it is about 30% of the blend.

Helena Viñedo - This vineyard is located just north of St Helena. With only 2 barrels of Cabernet produced, this is a very minor player that is not a part of the current finished wine but will be a part of future vintages. This area is the warmest site that he sources from for his blended Napa Cabernet Sauvignon. He stated that "it just gets super hot there creating a jammy, cooked blue or blackberry character." This sample is richer and more densely mouth coating.

Meadowbrook Vineyard - Located at the mouth of the Dry Creek canyon in the Oak Knoll District where it receives cool air rolling down from Mount Veeder which protects the vines from afternoon heat. This area has marine origin sediment, rocks, gravel, sand, and silt; the rocks have been dropped into a little alluvial fan. Matthiasson said that the drier conditions in this vineyard create more hormonal messaging from the roots to the vines leading to a red cherry fruit character.

Phoenix Vineyard - Matthiasson uses the grapes from this site for a single vineyard wine. The vineyard sits to the northeast of the town of Napa on a well-drained pebbly ash and loam soil hillside on top of cracked shale which is low in potassium and high in magnesium creating a lot of water stress which results in naturally low vigor vines and a longer growing season with the result of a high toned aromatic wine with red fruit and more structure.

The Finished Wine:

2019 Matthiasson Napa Valley Cabernet Sauvignon - This wine is a blend of most of the aforementioned vineyards along with a few more like Mount Veeder and Calistoga. Matthiasson's goal is to blend "a really flavorful, low alcohol wine to enjoy daily with meals." Each vineyard site is picked multiple times throughout harvest to get the grapes at their best before they become over ripe, he wants flavor but not sugar. Matthiasson strives to bring elements of each area to this Napa Valley designated Cabernet Sauvignon like the structured dusty notes of Rutherford with the edginess of Coombsville along with some of the soft red fruit of Oak Knoll. This wine is highly recommended.

More on this site on Steve Matthiasson and Matthiasson Wines:

The Farmer's Role in Terroir

Tasting at the Matthiasson Home Vineyard