Yesterday was Part 1 with Dr. Mark Greenspan, of Advanced Viticulture, about the Santa Cruz Mountains. Today is the rest of this interview with this world renowned expert in Climatology.
[Q] Can you define the Santa Cruz Mountains?
[A] It can be defined with varieties: Two sides of the mountain… anything from a cool climate Pinot to a warm climate Cabernet.
[Q] I’ve heard there’s a lack of frost in the Santa Cruz Mountains. Can you explain that?
[A] The lack of frost in the Santa Cruz Mountains can be explained, because the cool airs drains away and it goes to the valley floor; so, they don’t generally get much frost up there.
There’s a very distinct day/night diurnal – as you go up in elevation. We’ve looked at climates very carefully at two particular locations; one was in Oakville, and one was in Mt. Veeder. Both have identical heat summation degree days, 3,000 (pretty much, plus or minus by 100 every year). But the Santa Cruz Mountains have a very distinct day-night, diurnal temperature pattern. And that’s what makes the difference, because they have a totally different Cabernet in the valley than they have up in the mountains. The same thing’s true with any variety, primarily reds. As you go up in elevation the days are cooler and the nights are warmer. So they don’t get as big a diurnal swing between high and low, day time and night time temperatures.
An old wives tale is that you want warm days and cold nights. That came from, I believe, people who were growing wine in warm regions. They have to have a cool night if they have a warm day. But if they have a moderate day, they don’t need that cold night, because the heat that ripens the grapes also metabolizes acids, so they lose acidity. So, if you’re in a hot climate you needing that cold night to keep the crispness in the fruit and in the end wine. It can acidulate to some extent, but you really can’t make the same wine from a cooler climate vineyard that you can from a warmer climate.
The mountain gives you that the advantage of both. It gives you the same amount of heat summation, but you don’t get the heat extremes; so that during the day it doesn’t get as hot. And heat can really damage fruit; beyond changing it to the right thing, it can actually damage the fruit giving you off flavors… raisiny characters or cooked characters. The other thing it does, is have that warmer night (and I don’t mean warm, I mean 55-60 degrees, instead of 45 degrees), and the metabolism of the grapes stays active at nighttime. Not as much as it does in the day time when it’s warmer, but it still stays active. I call it night ripening. At that point, it’s not accumulating sugar, because there’s no using photosynthesis at nighttime from the sun. But by keeping the berry metabolism going, you’re maturing tannins and all the flavor compounds are being made, sort of as a by-product of the basic berry metabolism. In effect, it keeps going at night time, and you’re still making those products and ripening grapes at night without bringing in sugar. So, you tend to get riper fruit in the mountains at a lower brix. This gives you, to me, a lot more leeway in the stylistic abilities of that site, because you can go ahead and wait until 26 brix, and you’ll have a really ripe flavor and a really mature tannin. Or you can pick it more at 25 or 24 ½ brix, and still have a ripe tannin, but you’ll have a more delicate style wine.
[Q] What about in the valley?
[A] In the valley, on the other hand, you don’t have that leeway, because you’re waiting and you’re waiting for the tannins to get ripe, when you’re already at 26. By the time you’re at a 25 brix, sugar stops accumulating in the fruit anyway, it just starts dehydrating. It’s just the natural physiology of the grape. It just runs out of gas, and starts to break down basically. You talk about all this “hang time,” and how bad it is, and how all the growers are complaining about it. You have that problem in the valley, but you don’t have near that problem in the hills, assuming you have water available.
So that’s what we’re really finding about mountain climate. That’s probably 90 percent of why that Santa Cruz Mountain appellation has been so successful; whether it’s economically successful; at least viticulturally and ecologically successful to make great wines from the fruit, is because it’s mountain vineyards. If those vineyards were flat, it wouldn’t be the same.
That’s the climate in a nutshell, putting it only into the perspective of temperature. And, I do that all the time because the berry doesn’t know whether if it’s foggy or not, but it reacts to temperature; and then, humidity will have an impact obviously on other things, like disease, more than it would on berry ripening.
So there’s that aspect.
[Q] Are there other aspects that exist about the Santa Cruz Mountains that we haven’t covered?
[A] The other aspects have to do with drainage and generally shallower soils. Shallower soils allow us to control the water better. You find some dry farmed vineyards, but not a lot in California.
[Q] Is it better to just let vines be dry-farmed, and allow all plants to just go down on their own looking for their own water supply to become strong, allowing the plant to find its own water table? Is this the case for a mountain vine?
[A] Not necessary. It could be, but it really depends on the soil. People ask me all the time, “If I irrigate deeply, won’t the roots go down there to get water?” But in the North Coast of California, including the Santa Cruz Mountains (and this primarily refers to the western side of the Santa Cruz Mountains, I don’t know if it’s true on the other side, it may be) we have enough rain fall that we start every year out with plenty of water… Even this year, we had limited rain fall, but it finally did fill up by the end of February. The profile from top to bottom is full of water, it’s not saturated but it’s at field capacity. Right now (this was a Q&A in April) while the vines are dormant, there nothing taking up water except for weeds and cover crops (yet) in the vineyards.
I say the roots are going to grow wherever they can, because we’re in a relatively wet climate. So, irrigation doesn’t change that. What it does is… after that water pool dries up, then all the water it does get, roots that aren’t in a wet zone will go dormant, and we get active roots only where there’s water. So I don’t think you can force roots to go down there in a wetter climate.
[Q] On the mountain how much is top soil and how much is mountain rock?
[A] Generally I think you have more shallow top soil on mountains. Technically there’s probably just a few inches of top soil with some partially decomposed sand stone. It just depends on the local topography and geology. The bottoms of the hills collect water and there’s more soil there; they don’t need to be irrigated. Vineyards with sand stone need more irrigation and fertilization, and it makes more intense wines. As an appellation on the whole, compared to Napa and Sonoma – for instance – you don’t need as much irrigation.
In the Santa Cruz Mountains, you have to think quality, when you’re growing grapes there.
[Q] What about Chardonnay in the Santa Cruz Mountains?
[A] Chardonnay grows in a more diverse and wider range of climates than Pinot Noir. Pinot Noir is very restrictive on the coolest end of the spectrum; whereas, Chardonnay starts about in the middle of the Pinot range ~ and not quite as cold, actually, but you can grow it in much warmer climates. But, if you grow it in a cooler fringe, you’re going to get the most varietal express. Chardonnay grown on the coolest fringe definitely get tremendous varietal expression here is real fruit forward.