Let’s work with science first. Empirical evidence suggesting a correlation between a flavor profile and a particular type of soil has been difficult to reproduce with similar soils in different locations. This is the bane of scientists. To be true, a process must be repeatable with the same result. There are far too many variables in a specific vintage in a specific vineyard to repeat an experiment and say for certain that it is the soil that results in a particular flavor from that wine. Over many years you can remove vintage variation and recognize a certain flavor component from a specific block or vineyard. But what about the clonal type of the variety? What about the climate at that vineyard? What about trellising and other farming practices? And we haven’t even mentioned winemaking interference. Minerality in a wine such as our Roussanne is probably not a direct expression of the minerality of our soil (our soil has high mineral content). No one can prove or disprove that. We do find minerality in our Viognier and our Chardonnay as well but would we in a warmer vineyard with the “same” soils? Hmm? In the end, it is likely our climate may have more to do with the mineral expression in our wines – well, climate and vine stress. Soil does have a key role in vine stress. Vine stress indicates the degree of nutrient and water availability to the plant. To a degree, increased vine stress induces concentration, intensification, and the complexity of flavors in wine.

Our vineyard is part of an uplifted sea bed that was pushed into the air around 7-8 million years ago. You can find scallop and nautilus fossils in the soils. But, despite this history, these are not the basic limestone soils of Burgundy. Millions of years of decaying forest have increased the pH of the soil so it is fairly neutral and is composed of a fine, silty, sandy loam, with a modicum of clay interspersed in the subsoils. It is high in inorganic matter and low in most nutrients. The low nutrient content allows us to control and maintain the health and vigor of the vine, leading to small but healthy fruit loads and keeping vigor in check. If we had abundant available nutrition in the vine (lots of nitrogen e.g.), the plant would produce lots of shoots and leaves and be a very happy plant that would grow to the sun. But we are farming grapes, not leaves. We want the vines to produce shoots and leaves and set fruit and then begin to run out of nutrients and water and begin to create flavors in the grape skins as the summer comes to an end. That way we end up with a diverse and intense range of flavor in the wines.

Water is necessary for plants to live. If you grow plants in a region with consistent summer rainfall, the sky may be your source of water throughout the growing season. In Continental grape growing regions like Burgundy, for example, it usually rains during the summer and water is available to the roots near the surface of the plant. In a region like California, however, where it does not rain in the summer, the source of water comes from sub-aquifers like old river beds or from deeply saturated soils from the winter rains. In addition, water could be sourced from external sources like a reservoir. No matter where the water comes from, drainage matters as it dictates how long that water is available to the plant. Drainage is based on a few factors but, most importantly, the grain size of the soil.

Large grain soil drains quickly as there are more open areas for water to flow. Small grain soil (clay) does not drain well as it is very compact and water – not to mention roots – have a hard time penetrating. If you farm grapes in sand (large grain) you will need to water early and often unless you farm on an old river bed (in a valley, for example) where the roots have found sub-surface water. In either scenario, you may struggle to make high quality wine as the abundant water would lead to very happy grapevines that put out lots of shoots and leaves but would not experience the stress levels necessary for the vine to transition into veraison when the grape skins take on color, flavor, tannins, and sugar and to keep water content in the grapes in balance. You have had wines from those happy plants; they are somewhat dilute, simple, plonky.

If you farm in high clay content soils, you may have the inverse problem. The vine’s roots cannot penetrate clay and you will farm in the shallow topsoils which means you will run out of nutrients and water if you are on a hillside. If you are on flat land in a valley, your vines may also experience “wet feet” which is harmful to the vine and fruit.

Being on a hilltop formed by a river gorge, our soil drains downward over the course of the growing season. With our high winter rainfall, our soils are well saturated at the beginning of the growing season. There is no water table here as there are in most bottom lands. Water availability depends on the ability of the roots to penetrate the soil and to follow the water horizon as it recedes deeper into the earth. The fineness of our silty marine sedimentary soil impedes the roots’ progress, but not entirely, allowing for the slow penetration of the top five feet of soil. Our twenty-two year-old vines have fully developed, deep root structures that penetrate deep into our soils and have access to water late in the year. In certain areas of the vineyard, irrigation is often necessary in August to maintain the right level of stress – too much stress, and the plant will shut down completely. In those blocks we need just a shot of water to get us through the heat spells we often have around Labor Day and into the cool fall harvest.