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Low Desert Grape Variety Selection, Reconsidered
Recently someone asked why I chose the varietals I did for the first vintage of Laramita Cellars wines. Then, days later, someone else asked for recommendations for a high desert vineyard. I'm also starting to plan a second high desert vineyard of my own. So you won't be surprised to learn that varieties and varietals (the former refers to grapes, the latter wine) have been on my mind a lot lately.

Back when I started my backyard, micro-vineyards in Mesa and Queen Creek I was told that I was crazy and that wine grapes wouldn't thrive, or even grow, in the extreme heat of the lower deserts. I figured I could get something to grow and possibly even produce fruit, but I wasn't sure what. So I started planting small numbers of vines of every variety I thought might work. Among these vines were varieties you've heard of, like Syrah, Grenache, and Petite Verdot, but there were also some unusual choices. These included the Arizona Grape (Vitis arizonica), Norton, Mars Seedless, and Concord Seedless, among others.

Some might be surprised to learn that before urban sprawl consumed them, there were a number of huge table grape vineyards in the Phoenix area. Grapes from these vineyards ripened quite conveniently in a gap between grape harvests in South America and California thereby filling a niche for the North American market. But urban sprawl and advances in fruit storage conspired to eliminate these vineyards. Still though, if table grape vineyards can thrive in the heat of the lower desert, then wine grapes ought to have a chance.

It turns out they can, well, sort of. Here are the main issues with growing wine grapes in the lower deserts.
  • Low acid/high pH.
  • Poor color and tannin in reds.
  • Muted aromatics in whites.
  • Stalled Brix.
There are other issues, but they don't require discussion since they don't necessarily influence variety selection.

The acid issue is simple. The high temperatures drive off acids while the grapes are ripening. But the Brix issue requires some explanation. Normally in a warm climate the Brix, or sugar level, is driven sky high. That can happen in the lower deserts of Arizona, but what's more common is for the Brix to stall as the heat cranks up in June. Vines basically shut down in the heat. For example, for most red wine grapes 25 degrees Brix would be a good target for harvest, but in the lower deserts it might stall at 20 degrees Brix for weeks during a hot spell (which is typically the whole month of June). Now, remember that acid issue? The extra hang time necessary to get the grapes close to the desired Brix just gives the acid more time to evaporate. One problem exacerbates the other.

The extreme heat also causes others issues. Color and tannin never develop as well in the lower deserts as they do in cooler climates, and the heat can also drive off volatile aromatic molecules that give wine its "nose" or aroma.

So, if I were starting over again with my low desert experiments in viticulture, here's what I would plant:
  • White Wine Grapes
    • Petit Manseng
    • Picpoul (Piquepoul Blanc)
    • Muscat
  • Red Wine Grapes
    • Tempranillo
    • Syrah (on its own roots)
    • Barbera
  • Table Grapes
    • Flame Seedless
Petit Manseng and Picpoul are on this list because they have extraordinary amounts of acid. Muscat has incredible aromatics; more than enough to persist through the hottest of Phoenix summer heat. Among the reds, Tempranillo is just a sold performer, Syrah does quite well in Arizona and it performs best when it's grown on its own roots (not grafted), but Barbera is the real stand-out among reds. Remember that issue with the Brix stalling? Well, Barbera doesn't seem to suffer from it. The Brix just continues to climb slowly regardless of how hot it is. And the acid is better than about any other red wine grape variety as well.

Table grapes aren't really of interest to me, but a lot of folks like to have a few table grape vines in their yard. Thompson Seedless is a great performer, but the grapes are naturally quite small. Making them larger requires either the application of gibberellic acid or the girdling of the vine early in the summer. For this reason Flame Seedless is my recommendation.

Well, that's what I would plant if I were starting a new vineyard below 2500 ft in Arizona. By the way, if you want to see what I wrote about this eight years ago, check out this link. You'll see that my advice and my concerns have evolved since then.

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