A Late-March 2018 Bud Break Marks a Return to a "Normal" Spring

Two months ago, I was worried. January, normally our coldest month of the year, had seen only four nights drop below freezing. After one decent storm on January 8th and 9th, the rest of the month was dry, leaving us at just 20% of normal rainfall by month-end.  We ended the month with a week of sunny days, each topping out in the mid-70s.  The beginning of February was more of the same: ten days of sun in a row, each topping out between 75 and 81, with lows dropping down only into the 40s.  I was worried we'd see our vines start to sprout in February, setting the growing season off to an unprecedentedly early start and leaving us an unconscionably long period of frost risk.

Thankfully, mid-February brought a change in the weather pattern. Although the second half of the month remained dry (the 0.28" of rain is just 6% of what we'd expect from our second-wettest month) it got cold. We finished February with ten straight frosty nights, all but one dropping into the 20s. Only one of those days made it out of the 50s. And then, in March, it began to rain. We've seen fifteen days this month with measurable precipitation, totaling 11.94" for the month and bringing us to 16.54" for the winter, roughly 75% of what we would expect on this date. The vineyard has transformed, green cover crop springing from the ground as though it was making up for lost time. Now that we've passed the spring equinox and are in the middle of a week of sunny, increasingly warm weather, it's not surprising that I saw the first signs of bud break when I got out into the vineyard yesterday. Our viticulturist Jordan Lonborg provided photographic evidence with a photo of a sprouting Viognier vine this morning:

Budbreak, as you probably guessed from the name, is the period when the grapevine buds swell and burst into leaf.  It is the first marker in the growing cycle, a point when we can compare the current season to past years.  Upcoming markers will include flowering, veraison, first harvest, and last harvest.  And like harvest, budbreak doesn't happen for every grape simultaneously. Early grapes like Viognier, Grenache Blanc, and Vermentino tend to go first, followed by Grenache and Syrah, then later Marsanne and Picpoul, and finally, often a month after the earliest grapes sprouted, Roussanne, Counoise, and Mourvedre. And it really is just starting. Even Grenache, typically on the early side, was fully dormant everywhere except the very tops of the hills:

While this year is two weeks later than last year's budbreak, and a month later than our record-early 2016, it's only about average for what we'd have expected historically:

2017: Mid-March
2016: Very end of February
2015: Second week of March
2014: Mid-March
2013: First week of April
2012: Mid-April
2011: First week of April
2010: Last week of March
2009: Second week of April
2008: Last week of March
2007: First week of April

The timing of our cold and our rain was pretty much ideal. Grapevines (and all deciduous plants) pay the most attention to soil temperatures in deciding when to come out of dormancy. And wet soils retain cold better than warm soils. The double dose we received of cold and wet meant that despite the lengthening days, the vines' most important sensors were telling them that winter was still in effect, and sprouting would be a risk.  And, in fact, budbreak does begin our white-knuckle season, since while dormant vines can freeze without danger, new growth is susceptible to frost damage. April frosts cost us roughly 40% of our production in both 2009 and 2011, and we don't feel truly safe until mid-May. So, we've still got more than a month to go before we can relax, and it will be a few weeks before our later-sprouting varieties and our lower-lying (read: more frost-prone) areas are out enough to be at risk. 

But in general, if you could design a favorable winter weather pattern, it would look a lot like what we've seen recently. We'd ask for regular frosts and rain through the end of March, and then a switch to a warm, dry pattern thereafter. While we're always grateful for rain, since frosts tend to follow in the wake of frontal passages, the precipitation you get in spring storms isn't worth the risk of frost damage.  And the current long-term forecast calls for the high pressure system that has dominated our area this week, bringing sun and increasingly warm days, to persist for a while.

That's just fine with us. Now that the first vines have begun to sprout, we'll see the scene in the vineyard change rapidly. Please join me in welcoming the 2018 vintage.