Droughts & Wine Grapes

I get asked all the time, “How will the drought affect the grapes, will they be OK?”  My response is the same every time, I politely smile and say, “the grapes will be fine, it’s the wells I worry about.”  In fact, what many people don’t realize is the West Coast, more specifically, California has a drought every year from May through October, the time most crops are grown.  Irrigation is the life blood of agriculture.  To date, this year has been one of the driest on record with a total of 9 inches of rainfall since October (usually we get around 18 inches).  However, looking at the vineyard today, it is impossible to see any effect on the grapes.

In a normal year, the winter rains fill up the soil profile and we typically don’t start irrigation until mid-May.  Usually by this time the available water in the soil is depleted and we have to begin irrigation.  This year we started irrigating in February because we needed to fill up the soil profile in anticipation of bud break.  This process of winter irrigation is only practiced in the driest years.  As the vines began to grow, adequate amounts of water must be available to the roots, so by winter irrigating we are compensating for Mother Nature’s inadequacies.  As we enter the summer we will begin our regulated deficit irrigation program, which is essentially a diet we put the grapes on.  We have defined the amount of water we should give our grapes to be about 55-60% of total demands.  This practice allows us to grow high quality wines, but gives us a narrow margin of error.  Having no excess water in the soil, a broken pump or a well going dry can have damaging effect.  However, we closely monitor our wells and test them routinely.  We also utilize backup systems and we can typically see a problem before disaster strikes.  The system works so well, we constantly have to remind ourselves, “You never miss the water until the well runs dry.”