Grapes have the ability to deliver nutrients, water and sugar to any point in the plant at which they are needed. It’s not just a matter of raising the vines into the sun.
In fact, much of the work in vineyards consists of increasing stresses on fruit so that the vines will compensate. For example, if one prunes the vines hard, vigorous new growth will result. If one then reduces the number of grape clusters and exposes them to the sun, the vines will compensate. A viticulturist will tell you that the vines concentrate their essence in grapes when the yield is low. That is not exactly it. One thing you’re going to want to do is expose the skins of the grapes to the heat, so they will be stressed. The resulting acids in the skins are the building blocks of the flavours you can make in the back room with your yeast, and the plant’s attempt to balance the stress will make sure lots of sugar gets deposited in the grapes. Don’t let anyone tell you that this is terroir. It’s just stress. However, have a look at a different environment:
The blooming tree here is a feral black cherry growing amidst some wild choke cherries. If it were a grape, it would be lying over the top of the choke cherries and, like the black cherry, keeping its roots cool and its grapes warm in the sun. This would be different than the grapes in the vineyard just up the hill from here (which you just saw), where the vines are hot, the soil is hot, and the grapes are hot.
You are going to get a different wine from both settings. Rather than the leaves dropping water and sugar into the grapes to rescue them, you would have a gentle flow washing over them in one direction with cool water rich with minerals and then back with warm water rich with sugar. One of the minerals present is going to be potassium. You can see the missing potassium above in al the pruned-off canes. Without potassium, especially in high alkaline soils like these ones, nothing much happens. What’s more, it just blows off in the wind. However, if it is sheltered, it does not. Healthier leaves, at different ages of maturity and differing efficiencies of photosynthesis are going to give more complex wines. Now, let’s go one step further, just to the side of the vineyard:
Here we can see how grapes might further extend their ability to move sap in two directions. Grapes rooting at the top of these rocks, with seeds deposited by birds, let’s say, would drape down over the heat-soaked rocks, then root again in the shade below them, where the water the rocks shed collects. This water would be available to pass up through the tree-cooled trunks of the vines, into the warm fruit, and to nurture the dry roots on the ledge above. Those dry roots in turn, would grow early in the spring, making for earlier-sprouting grapes. You would gain weeks and a whole whack of sun, with a steadier, less stressful transfer of minerals, water and sugar, gently balancing the acids. In other words, the stress grapes are put under is not terroir, as the wine guys say. It’s just a cheap and easy fix. In the search for fine wine, though, you’re going to have to figure out how to plant on a cliff like this, without irrigation. The balance in the wine comes from the balance in the vine. You can’t force it. Well, you can, but it tastes, well, forced.