Growing grapes in the Antelope Valley?

A new AVA (American Viticultural Area) is being sought in Los Angeles County.  This article here describes the petition for the Antelope Valley AVA.

You don’t know where the Antelope Valley is?  When our local weatherman Dallas Raines (yes, he says this is his real name) mentions “the high desert” you’ve hit the target.  Think Lancaster, Palmdale, Edwards Air Force Base … and the Mojave Desert is not too far away.

Hmmm…. you might be wondering … is it wise to be growing grapes in Antelope Valley?

The summary description of the soil in the area sounds pretty good:  Boundary lines for the AVA closely follow the highest elevation of alluvial fans and terraces weathered from granite and other rocks in the surrounding mountains, providing deep loamy fine sand to loam and silty clay soils, well-drained and aerated in the root zone and mineral rich with low to moderate fertility.

But then we get to these interesting bits: valley precipitation ranges from 4 to 9 inches, with little or no snow, and the growing season is 240 to 260 days … although an average of 110 days per year register high temperatures above 90°F…

So, why is this a problem?

The grapevine needs an average of 25 inches of rain per year.  This means that mother nature will only provide for 16-36% of the water needed to grow grapes in this area.  So the rest will have to be piped in by man.  True, grapes can be grown very successfully with the help of irrigation – think of the Colombia Valley Washington and Mendoza Argentina.  But this is Southern California where we don’t have enough water to begin with.  In this day of fighting over delta smelts, water rationing and general water shortages throughout the state – one has to wonder – is it wise to be growing grapes in the Antelope Valley?

Another, equally important point, is that photosynthesis begins to shut down above 90 degrees Fahrenheit.  Photosynthesis is the process that transforms sunlight into carbohydrates and ripens grape flavors.  Optimum temperature for photosynthesis is 77-82.5F.  So in the Antelope Valley, 40-45% of the days in the growing season will have a significant number of hours where it will be too hot for growing grapes.  When almost half of the season’s growing days have sub-par growing conditions – one has to wonder again – is it wise to be growing grapes in the Antelope Valley?