vigor and math

I am old enough to remember those old Geritol commercials that promised vigor if you took the tonic.  Vine “vigor” is something that’s also of utmost importance for the production of good grapes and the great wine they can make.  Remember that, although you can make bad wine from good grapes, it is only from good grapes that you can make good wine.
 
Teleologically speaking, a vine’s work is to perpetuate itself via propagation.  This can only happen by spending a significant portion of its energy in making seeds, which as you know, are inside the grape berries.  To better target that outcome, farmers and wine makers train the vines to direct their energy accordingly so that the end product are grapes that, albeit smaller, have the best concentration of flavors and ripeness.  Well beyond the evolutionary changes over centuries that have given wine grapes (as opposed to table grapes) the best skin to pulp ratio (the “grapeyness” is mostly in the skin), there are vineyard interventions that help target the grape bunches.
 
A vine left to its own devices will grow an unruly canopy to make as many grape bunches as possible.  In fact, in ancient times some vines were trained to grow up larger trees.  The problem with this much “vigor” is that the sugars and “grapeyness” of so many bunches are diluted to the extent that the flavors are not as intense because an unruly leaf canopy will also take away from the energy the vine would otherwise use to better its means of propagation (remember the grapes?). 
 
This is why grape farmers will implement certain techniques in order to force the vine to focus its vigor, even if it means reducing it, so that the berries are the main object.  The key is to induce a certain amount of “distress” so that the vines are conned into making better grapes.  Among the different things that can be done at the vineyard, canopy management is vital.  Not only it forces the vine to pay more attention to the grapes, but it also allows for better sun exposure of the berries which in turn enhances ripening.  Sometimes, when there is an overabundance of bunches (too much vigor), a “green harvest” is carried out.  This is a process by which certain green grape bunches are cut and dropped on the ground.  Water management is also crucial.  The old adage “vines don’t like wet feet” pertains to the idea that when a vine has to “struggle” for water, it will spend a lot more of its energy in the berries.  This is one of the reasons why planting vines at hill sides and porous soils (significant water runoff) produce better grapes.  By the same token, vines can also be “distressed” by being planted closer to each other so that they have to compete for water.
 
The end product of all this vineyard management is to keep the vigor under control so that yields are restrained.  For instance, a very vigorous vineyard could produce up to about 10 tons of fruit per acre.  But these berries would not be of the best quality as they would not have the concentrated flavors from vines that would have been forced to pay extra attention to lesser amounts of grapes. 
 
With that in mind, a quality vineyard will produce about 3 tons of grapes per acre.  Each ton produces a little bit above 2 barrels of wine and each barrel contains 25 cases.  Since each case has 12 bottles, this 3 tons/acre vineyard will produce:
 
3 tons x 2 barrels = 6 barrels. 
6 barrels x 25 cases = 150 cases x 12 bottles = 1,800 bottles.
Considering that there are 600-800 grapes per bottle, that’s almost 1.5 million grapes! 
 
Nice vigor...even if you take it easy with the Geritol.