Why flowering 2019 indicates a later-than-normal but robust, high quality harvest

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 on at least a somewhat later track.  Flowering, which we began mid-May but which is still widespread as we get into mid-June, is confirmation that we're looking at a growing season more like last year's than what we got used to the rest of the decade. An example, from one of our Grenache blocks on June 3rd:

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. As with all parts of the vineyard annual cycle, there are grapes that enter (and exit) flowering earlier and later, with the early grapes being Viognier, Grenache, Grenache Blanc, and Vermentino. They are followed shortly by Marsanne and Syrah, and finally, as much as a month after the early grapes, Roussanne, Counoise, and Mourvedre bring up the rear.

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, the cool spring conditions seem to have delayed flowering long enough that even our late rain in mid-May seems to have rolled through before the flowers were open enough to be susceptible to much damage, and conditions have been ideal ever since. We are cautiously optimistic that shatter won't be a major issue. (It's also worth remembering that overall, conditions in Paso Robles are pretty benign compared to what grapevines face in most parts of the world.)

I always think it's interesting to compare our current year to a range of recent ones. A quick line graph may help give you a sense. I've put the line for 2019 in red, to help it stand out:

You'll likely notice a couple of things. First, May was actually cooler than April, for the first time this decade. And it felt like that too. April felt benign, with less than 0.1" of rain, no frosts, and an average high temperature of 73.4F. May was another story. The Paso Robles Wine Festival, which often coincides with our first hot weekend of the year, took place under conditions that felt more like February: low 60s, with rain threatening. We got seven days with measurable precipitation, totaling 1.44" (triple the 0.44" we average in a normal May). The average high temperature was 70.7F, and eighteen days failed to make it into the 70s. Five days failed to make it even into the 60s.

Second, you'll likely notice the rapid recovery of average temperatures in June. This trend actually began the last week of May, which was (fortunately) right when we first saw flowering. But even that warm-up has been modest, as we've yet to have the temperature here break 100. The next week looks like it's supposed to be in the 80s every day. That's pretty much ideal.

Looking for a comp is premature, as so much depends on what comes next, but it's starting off like 2015, where we ricocheted between significantly warmer-than-normal months and significantly cooler-than-normal months.  But it's also not that different from 2018, when a cool early season built to a scorching July before settling back down to a cooler harvest. But whatever the future holds, we do have a not-insignificant portion of the growing season behind us, and at this point we're 6.3% below our average number of degree days through June 16th, and 25.8% 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.  I'll keep updating you throughout the summer, as there's a long way to go.

At this point, we're happy to be most of the way through flowering in good shape, with the vines healthy from the winter rain we received and the lack (so far) of heat spikes, at the roughly one-third point of the growing season.  It's not just the grapevines that are flowering away. We've got blooms all over our olive trees:

And the California poppies are still putting on a show, at a time of year when they're often past their primes:

But the main event is, as always, the grapevines. We're thrilled with what we've seen so far. Fingers crossed for more of the same. And if you visit a vineyard in the next few weeks, take a sniff... the scent can be intoxicating.