Chronicles of a Dirt Farmer: How Our December Rain Will Affect the Vines


As recent weekends have tempted us with suggestions of Spring, the vines are slowly beginning to wake. We’re delighted to bring back RSV Dirt Farmer/Viticulturist, Debby Zygielbaum to bring us up to speed with the happenings of the vineyard.

“How will this rain affect the vineyards?”

That was the theme through end of last year. Now it’s February and I’ll have been complaining about the drought for two seasons running now.

When the skies broke loose in November and it just kept raining through early December, we breathed a collective sigh of relief and dared hope for a regular North Bay cold and wet winter. My reservoirs – mostly empty since January of last year — filled up in two weeks. Our use reports to the state water board will show empty in December and full by January with a note that, no, that’s not a mistake.

pond filling

credit Debby Zygielbaum

The pinnacle was a 50 year storm, with more water in a shorter time than we knew what to do with. I got a call from a new neighbor who’d just moved from SF —there was a river in what was supposed to be his front yard. (And our suspicious looking turbine pump by the road had to be somehow related – never mind it’s taking 200 gallons per minute from the flow and reducing the amount of water headed his way.) Welcome to Carneros, I told him. The soil cracks to the Southern Hemisphere in Summer and, if we’re lucky, we try not to float away in Winter.

But a normal winter was not to be. The spigot turned off abruptly — and stayed off — from mid-December all the way through January and most of February. Fortunately, the ground had been so saturated from the previous rains that it stayed wet for a month — lots of grass grew and we were able to go about business as usual (like bringing the sheep back! More on that in a future installment).

Full reservoirs and green hillsides took the sting out of the driest January in 165 years. The grass grew, the sun shined, the days lengthened until slowly, inexorably, the soil warmed up. Life begins to stir in the soil around 55ºF – microscopic flora and fauna start to be more active, the vines wake up and weep. Incredibly, we were seeing some sap flow in January. A colleague sent me pictures of unpruned Grenache in practically full bud break in early February — easily a month earlier than usual, if not more. We discussed what to do, which wasn’t much. Maybe wait to prune them just a little bit to slow them down? But then you run into the problem of stealing vigor from the vines, perhaps weakening them for the growing season. Or popping off the fragile shoots when trying to tie the canes. There really is no good solution — other than to just do what the season dictates, i.e. prune them now.

Black oak down

credit Debby Zygielbaum

The question changed from “how is all this rain affecting the grapes?” to “how is all this sunshine affecting the vines?” When it rains when it’s supposed it, it is just fine for the vines – the November rains were like a big drink to help the vines store up carbohydrates and put them to sleep for the winter. The last leaves fell off as the vines drifted off into slumber, canes dark and silent against the stark winter sky.

Water logging, regular cold (down into the low 30s or high 20s at night), wind, whatever, the vines are dormant and not disturbed at all. The rain can fill up the soil profile and the vines can get some cold hours to help them be dormant. Cold weather also kills insect pests (and there is some evidence for killing diseases, like new infections of Pierce’s Disease). So, a regular winter — cold, wet, wild, is actually quite good for the dormant vines.

All this sunshine, however, is waking them up early. Making them more susceptible to frost and speeding the growing season along. Thus we anticipate another early budbreak, perhaps another early spring, and perhaps yet another early harvest — if that’s the case, it’ll be the third year in a row we would be finished picking by early October.


Debby Zygielbaum is the Vineyard Manager (or, as she’s fond of saying, ‘Dirt Farmer’), at Robert Sinskey Vineyards in Napa and a frequent contributor on Nopalize. She can be found @walkthevine on Twitter and Instagram.