If March, April and May were cool months, so were June, July and even August – until the final week. After a summer of seemingly endless 75° to 80° F. days, the end of August brought a blast of heat during which a practically unheard of 105° F. day was recorded in Carneros. Even with this heat spike, August was as cool on average as July. That situation proved problematic. The sudden heat had a damaging effect on berries that had known only moderate temperatures and had been exposed when leaf canopies were thinned. Those of us growers who did not open up the south sides of rows were fortunate to avoid such physical damage.

I found it fascinating that some neighbors with animals – chickens and rabbits   — reported losses during the sudden onslaught of heat. Our grapevines apparently were not the only life forms not acclimated to high temperatures that paid a price.

Growers did a lot of nail biting in September as storms threatened, bringing to mind the heavy rains of the previous vintage, and then failed to materialize. With fruit hanging at only 21° Brix, there really was no option to pick, anyway.

Warm weather finally returned at the end of the month and lasted longer than predicted – five days rather than three. Four days were in the high 90s and one day touched 100, enough to kick-start the harvest in Carneros.

We picked most of our fruit during the first week of October. The long hang time and thorough ripening produced excellent intensity. Knowing the season would be late, we had thinned fruit more heavily than usual, making sure clusters weren’t touching in anticipation of possible rains.

One pleasant surprise was that the vintage produced less expression of virus in affected vines. We kept a close eye on leaf water pressure readings, especially where there is virus. I don’t believe stress is a positive. I don’t like luxurious conditions, but neither do I want to interrupt continuity in those vines.

Another wonder of the vintage:  we achieved good sugars, in the 24.5° to 26° Brix range, but none over the top. And while we did some additional sorting on the vine, in the vineyard and in the winery, rot was not an issue as it was in another cool season, 2006. We had some raisiny berries on clusters that were really exposed, but that was only on the surface and it varied from site to site. Overall, the wines are very solid with nice chemistry – good acidity, pH and ripeness at moderate alcohol levels.

On Monday of this week, I tasted our Pinot Noirs, which have yet to go through malolactic fermentation and are still showing beautiful baby fat. When the sweetness and fermentation bouquets are gone, these wines will become adolescents, and some will retain an awkwardness and angularity into young adulthood, while others will develop finesse more rapidly. Sounds like a parent’s perspective!

Will these wines be as good as the wonderful 2009 Pinots? It’s very possible, but at this early juncture, I simply don’t know. I do know that we as growers worried a lot more this year. This was a vintage that demanded attention, and we had to listen carefully despite a lot of background noise.

September brought a return to moderate weather, but some damage had been done. With foggy, damp mornings the norm throughout the summer, growers had opened their leaf canopies to facilitate air flow and sunlight penetration as a hedge against rot and mildew. But protection against one concern left them vulnerable to another. Grapes that had not been acclimated to warm weather were suddenly exposed to intense sun and heat that shocked and sunburned as much as 30 percent of the crop in the warmest areas.

While we sustained a little damage to a few clusters, fortunately we are in a cooler region. Perhaps more significantly, our vineyard rows run east-to-west, and we don’t remove leaves on the south side, so we were not as exposed as north/south rows that are open to the west. In Carneros, the wind also can create a canopy flop in north/south vineyards, resulting in even greater western exposure to intense afternoon sun.

Labor Day usually seems to bring some change, either a heat spike or rainfall. This year we expected some rain, but received just a slight sprinkle. We had a little heat the following week, but it was good in that it pushed things along a bit. The vines progressed slowly through a cool month until we had a little heat wave last weekend that we needed to get harvest going.

Our Russian River vineyard is late, and my little vineyard at my home was later than normal, but parts of the Donum Ranch typically take until late September into early October to ripen. We finally harvested my vineyard and the Calera Pinot Noir selection at Donum last week, and one block of our Donum Roederer selection was ready as well.

For the past ten days, our weather has been ideal, and that’s the forecast for the coming week, too. The fruit is sound, and these wonderful 70-degree days and cool nights will allow slow, deliberate picking after plenty of hang time. The skins should soften and dimple, developing beautiful tannins and total ripeness and yielding really lovely, intense wines.

So we anticipate ticking along nicely, jumping from block to block to pick at the most opportune moment. Not the most difficult of harvest scenarios by far, and we should wrap up the 2010 vintage by the third week of October.

As the mercury approached high 90s F., the vines had moved into full bloom. Grapevines are rather vulnerable during this period and require moderate conditions for complete pollination. Extremes of cool, hot, dry or wet weather can interrupt the process.

A good synonym for a vintage is “weather pattern.” Each growing season is a collection of fog and heat and wind and rain events. As wine grape growers, we can’t control the weather, but we do try to react to it in an appropriate manner to obtain the end product we want.

This year, as in 2007, the heat and subsequent rapid and incomplete flowering gave us little shot berries and shatter – when less than ideal conditions cause the vines not to pollinate and the flowers don’t become berries.

Within the considerable variety of Pinot Noir clones and selections in our estate vineyards, there are some variations in fruit set, but we’re seeing lots of loose clusters and small berries. The combination of large and small berries in our Old Wente selection of Chardonnay is often referred to as “hens and chicks” or even “pumpkins and peas.” It’s said that there may be a fertility issue in Old Wente with zinc as a player, but we find micronutrients are generally not a concern.

At any rate, if we were only concerned with yields, with crop tonnage, shatter might be a big negative, but instead we are excited. As in 2007, this could be the making of an excellent vintage quality-wise. Loose clusters and small berries can translate into more even ripeness, a low probability of rot due to increased air flow, and higher skin-to-pulp ratios in the berries which concentrates flavors and aromas.

Most of June was mild and uneventful with a small heat spike at the end, and July has been similar, although we have had high 90s during this past week. Our relative humidity has been good as well.

Ten days ago as I walked the vineyards, I saw no signs of virus showing. A few days ago after some heat stress, it began to show up. I’ve also seen the first signs of color (veraison), but it’s less than one percent of the crop. It will be interesting to keep track of how many days it takes to reach 25%, 50% and 90+%.

With more humidity this year, we’ve seen higher mildew pressure. I have quite a bit in the roses around my house and they are always a good indicator. Chardonnay is particularly sensitive, so we made sure to have our canopies opened up for air circulation by the 4th of July weekend. We pulled leaves early and the fruit looks clean. It’s funny, today when we talk of quality, we don’t even think about clean fruit. It has become the standard.

I mentioned earlier the actions growers can take. Our primary tool of control is water. On the technical side, we have great tools to aid us in irrigating. We measure leaf water potential (LWP) by seeing how much pressure it takes to push the water from a leaf out through its stalk, the petiole. This reading is much like taking someone’s blood pressure or measuring blood sugar. It’s a snapshot of water content in the plant.

We combine that information with a measure of soil moisture levels – the amount of water available to our vines. The neutron probe is a remarkable instrument that emits neutrons that lose energy when they impact hydrogen atoms in water. A neutron detector indicates weaker responses to neutrons as soil water content increases. We take these measurements weekly.

Recently, our leaf water pressure numbers were running higher than we’d like and they didn’t correlate with the soil moisture numbers or my visual observations of the vines. It just didn’t make sense to me. We had more than adequate moisture in the ground, and temperatures were moderate, yet we were getting LWP readings of 12 to 13 bars. We generally don’t want any higher than ten, and I had expected a reading of between seven and nine bars.

I’ve run into similar situations in the past. In 1999, for example, our sugar sample numbers just flatlined and that didn’t make sense. The numbers need to tell a story. They should not become the story. If the story doesn’t make sense, you have to be alert and apply your experience. While technology and numbers are marvelous tools, you can’t rely on them blindly.

What we discovered was that our LWP machine was reading two to three bars higher than it should have. We borrowed another one to compare readings, and the numbers of the two machines varied by two to three bars.  The readings of the borrowed machine were in line with the visual state of the vine and the soil moisture level.  We have had our machine recalibrated. Luckily, we didn’t over-irrigate (although I would prefer to put on too much water rather than too little because once the plants are stressed, it’s hard to get them back to functioning well again).

We are fortunate to be able to factor in leaf water potential and soil moisture levels with vine transpiration needs and the weather forecast to make our use of water as a tool more precise. But this little incident illustrates that, despite our technology, perhaps our best tool is referred to in the old adage of the grower’s footprints in the vineyard.

You overlay years of experience with the site and the clones and you increase your understanding of what works when and where. Experience is the ultimate tool.

Heavy rains have brought us close to 20 inches for the season, very near normal, which is slightly less than 22 through this month. By comparison, last year we had just over 11 inches to date.

I have been sidelined with the flu, which has seemed ironic during this past week of warm, sunny days. Nabor has been busy in the vineyard, and with dry weather forecast, he should finish pruning our home ranch, The Donum Estate, and nearby Ferguson Block by early next week. Then we start tying.

I’m on the mend, so we’ll head up to Nugent Vineyards next Saturday and start there. The vines are still dormant. Nothing really happens until soil temperatures reach 50 degrees F., the magic number when the “sap rises.” Nothing in the vineyard is swelling, but I’ve seen a few trees starting to push.

The first half of February is pretty early for this kind of weather. We try to postpone pruning as long as possible because that delays bud break and lessens the chance of frost damage. The rains have given us nice cover crops, which, in turn, absorb the rainfall so that there isn’t much standing water. But Nabor and his team aren’t daunted by mud.

The cellar is buttoned up and Kenneth just left with his family for a well-deserved vacation in Mexico, near Cancun. Some wines are still finishing ML, or malolactic fermentation (conversion of stronger malic acid, found in apples, to weaker lactic acid, found in milk). While this winter has been moderate overall, there have been cold periods. Our late harvest put winemaking on a later schedule, including moving ML, which is temperature driven, into the colder months, further slowing it. But everything is proceeding nicely within an acceptable time frame.

Valentine’s Day is associated with the color red, but in the vineyards, there is a riot of yellow with the mustard out in abundance. I feel better just looking at it.

Even with clouds overhead today and temperatures barely in the 70s, Phil commented that enough sunlight gets through for photosynthesis (vines won’t grow in full shade). He said photosynthesis will “max out” in the high 70s and low 80s. Even the morning breeze aids the process of ripening by circulating fresh carbon dioxide among the leaves. Phil recalled being in the Nahe Valley in Germany one year for the last 30 days before harvest; even when three out of the four weeks were cloudy or rainy, the vines ripened the fruit.

Phil tasted our Donum selection and called it the “stealth clone,” noting that its flavors are ahead of the sugar levels. He thinks the flavors say we’ll harvest next week, but we may wait until the following week.

I heard Kenneth walking down a row tasting berries and muttering to himself, happily, “Plum, plum and more plum.” He checked the weather forecast on his cell phone and said we’re in for a steady string of low- to mid-80s days. “We just have to be careful and ride this wave,” he commented, relishing the thought of extended hang time.

We looked at NDVI (Normalized Difference Vegetation Index) satellite photos of our vineyards to view vigor expressed in color differences. There was a little less blue and green and more yellow this year, indicative of drier soils. Nabor said we could skip the first ten rows of one block for a few days and harvest the rest, in effect separating out flavor differences. He has confirmed on the ground what we see from above. He and Phil talked about marking a diagonal line with flags in the vineyard to focus the crew on the uniformly high vigor areas first. It’s a luxury to fine-tune this way, but we have the time to do it this year.

We drove from Donum over to the Ferguson Block and looked at some trials we’re running with one set of rows thinned normally, a second set that alternates one and two clusters per shoot, and a third set of rows with only one cluster per shoot.

The last time we all tasted here the fruit from one-cluster-per-shoot vines was ahead of the pack and tasted very nice. But now we agree that fruit from those same rows has thicker skins and no burst of flavor, whereas the “normally” pruned rows have caught up.

We will pick all of them the same day and then look at fruit composition, not only sugar, pH and total acidity, but also tannins and anthocyanins (phenolic compounds that contribute astringency and color). We can also look at yields, pruning rates and their ratios, and, finally, we’ll compare the resultant wines. Phil thinks it’s all a question of balance, for it’s as possible to be under-cropped as over-cropped.

We walked into a 6’x12’ block planted in 1974 and noted the old Martini selection of Pinot Noir here has smaller berries and thinner skins than Martini planted at Donum. Phil noticed a fairly high percentage of small shot berries here, but he also noticed they have held up well and aren’t dehydrated. The vine has been getting the water it needs and, indeed, we don’t see any yellow leaves.

Nabor and Kenneth joke about a long lunch because we just have to wait and pick at the peak. We all agree that we’re lucky – the water, canopies, sugars, flavors and weather forecast are all lined up. Phil reminds us that farming is hoping for the best while preparing for the worst.