How roots and soil impact wine flavor
Marnie also schools Buzz in why vintners need to graft wine-grape vines onto another species.
BUZZ: Hey, Marnie, can grapes grow indoors? My neighbor does hydroponic tomatoes in his sunroom, so why not wine grapes?
Marnie: Grapevines are more like little trees than tomato plants, Buzz. They need to put down deep roots and would require tending for decades. Besides, hydroponic grapes would make for pretty bland wine.
Buzz: Why's that?
Marnie: Well, hydroponic gardening uses no soil - plant roots are bathed in a nutrient solution instead. This produces decent flavor in herbs and greens, since leaves have a simple flavor structure, but grapes are more multidimensional.
Buzz: So, the wine wouldn't have complex flavors?
Marnie: Right. Grapes might taste sweet-tart and juicy grown this way, but their flavors are flattened when grown without real dirt, lacking intensity and complexity in their aromatic compounds. Nutrient water simply can't deliver the full range of soil micronutrients or sustain soil's microbiological life, and these are both key in developing flavor complexity for wine.
Buzz: I can't wait to tell Joe that his precious tomatoes won't taste good without dirt.
Marnie: They might taste pretty "good" but not great, because the plant is only one part of the flavor recipe - the place where it's grown contributes taste, too.
This location-specific flavor plays a much more noticeable role in fermented products like wine and cheese than it does in fresh produce, so soil and terrain are more important to winemakers than tomato farmers. Growing wine grapes indoors is simply not feasible in practice, even though I'm sure some vintners would love to eliminate the need for grafting their vines.
Buzz: Grafting? Why would they graft vines?
Marnie: The vinifera species of vines that make the best wines are vulnerable to a soil-dwelling aphid that attacks their roots. The only defense is to graft those fine grapevines just above ground level onto the trunk and roots of a non-vinifera grapevine species that is insect-resistant.
This is standard practice everywhere in the world, except for a few remote places where this pesky bug doesn't thrive, such as Chile. One reason Chilean wines are so good and so cheap is that this process isn't necessary. Vintners can grow "ungrafted" vines.
Buzz: Bugs? Graft? This is starting to sound like an FBI sting of corrupt politicians.