I have 350 vines on my property in Maryland as a hobby, not as a business. Its basically a test vineyard comprised of 11 reds and 4 whites. It’s also a young vineyard with the first vines planted in 2006 and the most recent in 2011. But from what I have seen a number of the things listed as reasons why quality grapes can’t be grown in VA really don’t seem to be issues.
Fall rain is probably the biggest issue and years like 2011 prove that out. Yet in many years its not much of a problem. Rootstocks for the east coast are predominately 101-14 and Riparia Gloria with some 420A more recently. These are shallow rooted stocks that were chosen to help control vigor and when planted on well drained soils do have less problems with late season rain. Most of the reds discussed in this thread harvest in October so August and even early Sept rains are not as much of an issue as has been implied. There are many years when fall rain does not impact quality significantly.
Humidity is a management problem. I have not seen it impact quality unless mildew or rot gets out of control. There are changes to viticultural practices that need to be used for the east coast such as leave pulling as early as bloom for more air movement and more stringent spray programs than one has in California. However, there is no real reason why this should impact grape quality.
Summer high temperatures I don’t believe is an issue. The area is hot but I am not convinced that the high temps in VA are worse than other hot regions where grapes are successfully grown. As noted by others location can reduce those temps for a specific microclimate.
Summer low temperatures is something I had feared before I started growing. One always reads warm days/cold nights is best. Yet, I am now unsure as to what is the benefit of cold nights. I have read its to retain acid yet acidity is not a problem for my yard (sand/gravel soil) and I have tasted wines from VA that are not lacking acid (Linden Avenius comes immediately to mind). Maybe they are acidified as I don’t know but the Avenius is always the most acidic of Linden’s reds and whites so I tend to believe its natural.
I thought short growing season was mentioned although I don’t see it now so either I missed it this time or imagined it before. Regardless, bud break is generally in April and harvest in October for the reds discussed in this thread. I don’t think that this is significantly shorter than elsewhere and there has not been an issue with ripeness in the short time I have been growing. I have read that the warm nights that we experience may actually be a benefit on getting to full ripeness since the vines rarely shut down at night.
Soils are varied and I am sure that there are many soils that are not suitable. I don’t know enough to dismiss all soils as unacceptable for quality grape production but that may be the case. In my case my sand/gravel soil drains great which is my primary concern but the soil pH is lower than I would like and I do have some problem related to that most often with potassium.
What I find to be the biggest issue is the general vigor of the vines. Excessive green growth can be a problem but proper rootstock, soils, use of cover crop and proper trellising makes it a managable issue.
Agree that Va should not be compared to bordeaux or california as it is different. But I am still not sure what it is about these differences that limit the abiltiy to consistently grow quality grapes in a properly chosen location. As with all regions, site selelction is key.