Harvest is certainly the pinnacle in the annual lifecycle of the vineyard. It is the culmination of everything the winegrower has been meticulously working for all season. My hope is that all the home winegrowers had as fruitful of a season as I did this year. Your efforts in the vineyard, however, are still not quite done; especially if you are a cold-climate grower.
In the months leading up to harvest the grapevine's entire focus was to develop and ripen its fruit. Once that fruit is removed, its focus changes. It starts gearing up for a cold winter's nap. To accomplish this, the grapevines focus their energy on building up carbohydrate stores and hardening off their shoots to survive the winter cold. Picture squirrels running around your yard gathering nuts and storing them in a tree to keep them alive through the winter months when food sources aren't available. Same thing. Well not really, but I like to try to make analogies.
During this stage of a grapevine's annual lifecycle they go through a stage of rapid root growth. The roots are what extract nutrients and water from the ground to build its winter stores. You can help your grapevines at this stage by providing them a heavy watering. This can either come from you or Mother Nature. If she has no plans in helping out, then you'll have to step up. In my vineyard, I attached some inexpensive soaker hoses along the bottom wire of my trellis, as pictured below.