Yes, July really was hot. But veraison still arrived late. What gives?

A month ago, I felt like I was tempting fate when I characterized the 2018 summer as "benign". Well, so much for benign. July was the hottest month we've ever seen here at Tablas Creek, with an average high temperature of 96.5 and an average overall temperature of 76.5.  Fourteen days topped 100, and only seven -- all toward the beginning of the month -- failed to get into the 90s. In terms of degree days, July saw us accumulate 844 degree days, fully 28% more than our average of 659. That's a big increase over what is already our hottest month:

2018 summer temps through July

Given the heat and the season, it really wasn't a surprise when I got an email from Neil on Monday with a photo of Syrah undergoing veraison. Veraison marks the point where a grape stops accumulating mass and starts accumulating sugar. More visibly, red grapes start their color change from green to purple, while white grapes take on more of a yellow tint. Both red and white grapes start to soften. [For more about what's happening chemically, check out this veraison post from the archives.] A few photos of Syrah clusters will give you a sense of what things look like now:

Veraison 2018 syrah 2

And:

Veraison 2018 syrah 3

It's worth remembering that most of the vineyard is still totally green.  Syrah is the first red grape to enter veraison, and I couldn't find even a hint of color on any of the others. And, that photo was from the top of our tallest hill, which is always more advanced than areas lower down both because they started earlier since their last frost was later, and because they're under more stress due to scarcity of water. But we know that once we see Syrah, the other grapes follow along in fairly short order.

One of veraison's principal values to a winery is as a marker: this landmark comes roughly six weeks before the onset of harvest, and gives us our best estimate for when harvest will begin.  But, of course, six weeks is a rough average, and can be influenced by the weather that we get in the interim, as well as by the amount of fruit the vines are carrying.  For example, in 2014 our earliest-ever veraison (noted on July 9th) was mitigated by a very cool August, and we started harvest 45 days later, on August 23rd. By contrast, 2016's first veraison was noted on July 13th, and combined with a very warm August to produce our earliest-ever beginning to harvest, just 36 days later. The last dozen years are compiled in the chart below, with each year linked to my blog post about that year's veraison:

Year First Veraison Noted Harvest Begins # of Days
2007 July 20 August 28 39
2008 July 23 September 3 42
2009 July 20 September 1 43
2010 July 30 September 16 49
2011 August 5 September 20 47
2012 July 25 September 5 42
2013 July 17 August 26 40
2014 July 9 August 23 45
2015 July 18 August 26 39
2016 July 13 August 18 36
2017 July 20 August 30 40
2018 July 29 ? ?

Using the range of durations between first veraison and first harvest (36 to 49 days) we can have good confidence that we'll begin picking sometime between September 3rd and September 16th. I'm guessing we start toward the early end of that range, given the warmth of the summer so far and the relatively moderate crop levels we've been estimating.

Given the heat in July, it's worth addressing why the vineyard hasn't caught up more from the roughly two weeks late it was after flowering. I'd point the finger at two culprits. First, we did catch up a bit; I'd estimate that we're more like 10 days behind than the two weeks we were in early July.  And second, grapevines photosynthesize optimally at temperatures between 30 and 35 Celsius (86 and 95 Fahrenheit). Two-thirds of our days in July got above 95 degrees, which means that the grapevines actually slowed down photosynthesis in the heat of the day as they closed the pores on their leaves to reduce dehydration.

What's next for the vineyard? We'll watch the different grapes go through veraison. Syrah will be followed by Mourvedre, then Grenache soon, and finally Counoise. In the cellar, we'll be getting the last of the year's bottling done so there's space in barrels and tanks for the coming crush, and starting the process of pulling out and cleaning all the tanks, barrels, and equipment we'll be using once harvest begins. Everyone will be storing up on sleep.

And now we know -- roughly at least -- how much time we have  left before everything shifts into harvest mode. Stay tuned.


A mid-summer vineyard assessment suggests 2018 is looking like a throwback to the 2000s

I feel like I'm inviting disaster just by typing this sentence, but it's been, well, benign so far this summer.  I got back from two weeks in Europe, some vacation and some work, to find a vineyard significantly advanced over where it was in the first half of June.  Vines that were just finishing flowering are now fully set, with early varieties nearly full-sized.  The Grenache, below, looks fully formed, though the grapes will continue to grow a little and there's no hint of color change yet:

Vineyard Summer 2018 Grenache

Fruit set looks good, with only minimal shatter, and the late rain that we received in March appears to have given the vines enough vigor to set a healthy crop.  We will surely be dropping some fruit this summer.

The vineyard looks vibrantly healthy, with even stress-prone varieties like Roussanne and Mourvedre still fully green.  This isn't a surprise; we've only had one day (June 22nd) top 100, and only 14 days reach the 90s.  That may sound like a lot, but the average nighttime low since May 1st has been 46 degrees, and a couple of days in mid-June didn't even make it out of the 60s. More measurably, in terms of heat accumulation (as measured in Degree Days at the weather station in our vineyard) we're still below our 20-year average, with May 18% cooler than normal and June just 5% warmer than normal.  I'm not sure if the health of the vineyard comes through in photographs, but it's (no pun intended) worth a shot:

Vineyard Summer 2018

Or, for another perspective, here's a shot from below the Counoise trellises, showing the clusters sheltering beneath their leafy canopy:

Vineyard Summer 2018 Under Counoise

How does this compare to other recent years, and what does it mean for harvest?  Well, our late-March budbreak, which kicks off the growing season, was about two weeks later than in most recent years, though more or less average looking at a 20-year perspective.  The weather since then has been quite a bit cooler than the years since 2012, but again, more or less average looking at the 20-year scale.  That's probably easier to make sense of in a graph.  First, the heat accumulation (in degree days) this year versus two averages: one of all years since 1997, and the other looking at just the recent warm stretch that began in 2012:

Summer 2018 Degree Days Through June

You can see that our recent years (in green) have been quite a bit warmer than the longer-term average (in blue), whereas 2018 (in red) is cooler.  That's perhaps even more dramatically illustrated by looking at 2018 in terms of percent difference from average.  All three months we've measured this growing season have been between 8.5% and 15.5% cooler than the 2012-2017 stretch:

Summer 2018 Degree Days Through June vs Normal

All this weather data just reinforces my thought that we're going to be seeing a harvest that's more like what we got used to in the 2000s (when we averaged 1069 degree days through June, nearly identical to this year's 1045) than what we've seen in the 2010s. The best comps to date are 2002, 2006, and 2009, all of which didn't see harvest begin until the first half of September. I'm not expecting veraison until we get close to the end of July.  Of course, there's still a long way to go, and there is a hot stretch forecast starting next week.  But we are at what's typically the hottest time of year, and it's still been moderate.  So far, so good.


Flowering 2018: Might We Be Seeing Our First Moderate Vintage of the Decade?

There are five viticultural markers that we use each year as markers: notable reference points that indicate where we are compared to other years.  These are, in order:

  • Budbreak (typically late March or early April)
  • Flowering (typically May sometime)
  • Veraison (typically late July or early August)
  • First Harvest (typically late August or early September)
  • Last Harvest (typically late October)

Budbreak gave us the first sign that we were going to see a later beginning than recent years.  Flowering, which we saw first evidence of in mid-May but which is still widespread as we get into the second week of June, is confirmation that we're looking at a growing season roughly two weeks later than what we've come to be used to since 2012. An example, from our Grenache block on Scruffy Hill in late May:

Flowering grenache on Scruffy Hill May 2018

If you haven't seen grapevines flowering before, you can be excused for finding it underwhelming.  It's not a showy process.  Still, the tiny white fuzz-like flowers that appear on the clusters are the first stage of development of the berries.  From this point on, if the berries are fertilized successfully, they'll grow in size and mass until veraison, at which point they stop growing but accumulate sugar and ripen the seeds within. 

During flowering, you hope for consistent, sunny weather, with only limited wind and no rain.  Cold or wet weather at this stage can produce incomplete fertilization, or shatter, where a cluster has a high proportion of unfertilized berries, looking snaggle-toothed and (often dramatically) reducing yields.  Some varieties, most notably Grenache, are prone to shatter, while others are less so.  This year, conditions have been good, and we are cautiously optimistic that shatter won't be a major issue. It's worth remembering that overall, conditions in Paso Robles are pretty benign compared to what grapevines face in most parts of the world.

2018 appears to be developing into something of a throwback. The rest of the years this decade have been pretty extreme at this stage.  In our warmer years (like 2012, 2013, 2014, 2016, or 2017) May has felt like early summer, with multiple days in the 90's and even low 100's.  In the chilly years (like 2010, 2011, and 2015) May has been more like April, with several nights dropping down into the 30's and most days topping out between the mid-60's and mid-70's.  What we're seeing is something more in the middle.  A quick line graph may help give you a sense. I've put the line for 2018 in red, to help it stand out:

Average Temps by Month 2010-2018

You can see that the 2018 trend line falls in the middle, in a space that's largely unoccupied (in May, at least) this decade. So, what does this mean for the rest of the growing season?It's too early to be particularly definitive.  It could develop into a year like 2015, where we ricochet between significantly warmer-than-normal months and significantly cooler-than-normal months.  It could build like 2012 from a cool early season to a scorching August.  Or it could settle in as a more uniformly cool or warm summer.  But we do have a not-insignificant portion of the growing season behind us, and at this point we're about 2% below our average number of degree days through June 6th, and 28% below our maximum to date (2014).  That cool weather, combined with a fairly late budbreak, suggests we're a couple of weeks behind most of our recent years, and unlikely to begin harvest before September.  Of course, there's lots that's yet to be determined.

At this point, we're happy to be most of the way through flowering in good shape, with the vines healthy from the March rain we received and the lack (so far) of heat spikes, at the roughly one-third point of the growing season.  And the vineyard smells great.

Flowering grenache on Scruffy Hill May 2018 2

We'll take it.