Interest in grape production has generated many questions about vineyard establishment and grape production. Here are answers to some of the most frequently asked questions we hear from the grape growing and winemaking industries:
Q: Where is the best place to acquire grape vine plantings?
A: Several commercial nurseries are available from which to buy vines. Most are listed in the Vineyard Supplies section. California nurseries typically only carry vinifera varieties. Hybrids can be found from the eastern nurseries, such as those in New York.
Q: Is it best to plant a single variety or multiple varieties?
A: It depends on the size of your vineyard. If you're planting 1-2 acres, then grow a single variety to get sufficient quantity to sell. Otherwise, consider growing more than one, perhaps several (depending on acreage). This helps to spread out the risk (losses to frost/disease, decreased demand for a particular variety) and the harvest (consider labor availability).
Q: Are there particular varieties that are in high demand/short supply that would readily grow in the Piedmont?
A: The majority of varieties appear to grow well in the Piedmont area. Popular varieties include Cabernet Sauvignon, Cabernet Franc, Chardonnay, Viognier, Merlot, Syrah (all vinifera), Chambourcin and Seyval Blanc (French hybrids). In addition, other varieties are beginning to attract interest and attention. More importantly, talk with the wineries you hope to sell to about the varieties they anticipate needing.
Q: What is the optimal size of a vineyard?
A: A vineyard should be at least 4-5 acres to obtain reasonable economies of scale and produce sufficient quantities (tons) of multiple (3-4) varieties. Upper limits are determined by market demand and your ability to grow and sell premium quality grapes. The optimal size appears to be at least five acres, probably no more than 10 acres for a new, unestablished vineyard that isn't making its own wine. The average size in North Carolina is five acres.
Q: Do grapes prefer alkaline or acidic soils?
A: Nearly neutral soils, pH - 6.2-6.5
Q: Where/how is the best way to learn the ins and outs of grape production?
- Get a copy of the North Carolina Winegrape Growers Guide. This is a good introductory text on the subject.
- Talk with people already operating vineyards.
- Attend industry educational and trade shows, such as the N.C. Winegrowers Association's annual meeting.
- Join grower associations.
Q: What considerations are important for growing grapes at higher elevations and colder temperatures?
A: Winter minimum temperatures will be the most limiting factor in variety choice at your site. Vitis vinifera varieties (i.e. Chardonnay, Merlot, Cabernet Sauvignon, etc.) are the least hardy of the bunch grapes and would be at a higher risk level of cold-injury or death. Most are only hardy down to between -5 and -10 degrees and can suffer a lot of wood damage at temperatures of 0 to -5.
Varieties such as Merlot and Syrah, which are gaining in popularity here are more cold-tender. Some varieties are slightly cold-hardier, such as Cabernet franc, which is a better choice in our area than Cabernet Sauvignon (much more grower friendly). This would be a possibility if the site is higher on the hillside with a good slope and plenty of air drainage.
Riesling is also a more cold hardy variety. We don't recommend Riesling as a commercial variety due to its susceptibility to fruit rots in our summer heat and humidity, but in a smaller scale "hobbyist" planting you might want to try some.
Your best bet will be with hybrids and American varieties, which are more cold-hardy (from -10 to -25 degrees, depending on variety). American varieties worthy of your consideration are Concord, Niagra, Delaware, and Catawba, all of which have been successfully grown in the mountains and used for wine. The hybrids make very good wines and are more reliable croppers due to their higher level of cold-hardiness and their tendency to set near-full crops on secondary shoots, making them more frost tolerant than vinifera varieties.
There are several varieties from which to choose. Hybrids and American varieties haven't been widely planted in North Carolina, but Chambourcin, Vidal Blanc, Seyval Blanc, and Villard Blanc have done well. I've also had a very good wine made from Baco Noir grown in Ashe County (elevation around 3200 ft). Other hybrid varieties worthy of consideration are Traminette, Chardonel, DeChaunac, Ives, Marechal Foch, and Leon Millot. This list is certainly not all-inclusive.
You won't find the American or hybrid varieties at the California nurseries; they deal almost exclusively with vinifera varieties. But all the varieties mentioned, and others that you might want to experiment with, are available at many eastern grapevine nurseries, particularly those in New York.
For a list of nurseries and contact information, visit our Vineyard Supplies section.
Q: Which grapevines are grafted and why?
A: All vinifera varieties are grafted onto rootstocks (the only way they'll survive our soil-borne pests). Hybrid varieties may or may not be grafted (depends on the nursery). All grafted grapevines need to have their graft unions protected from hard freezes each winter, typically by "hilling up" soil around the vines (covering the graft unions) in late fall and leaving it over the graft unions until after the last frosts in spring. This needs to be done at least until the vines are five years old, but is best done every year with vinifera varieties, which are more at risk for winter-kill.
Q: Assuming a vinifera vineyard spaced at 6 ft. between vines and 10 ft. between rows, and trained to a Vertical Shoot Positioned trellis, how much does one acre of grapes produce, how many vines would that acre contain and how many pounds on average can one expect from each vine in this configuration?
A: Approximately four tons is the upper allowable limit. The vines can produce more, but fruit quality begins to suffer. Using a divided canopy trellis such as the Lyre or reducing between row spacing (i.e. to 8 or 9 ft.) can increase yields to 5 or 6 tons per acre. By the same token, poor vineyard management can reduce yields even if all other factors favor high yields.
At 6x10 ft spacing, an acre would contain 726 vines.
The vines would carry 11-12 pounds each.
Q: What is the average spacing of vines in North Carolina?
A: As the model states, average is around 6x10 feet. For Vertical Shoot Positioned trellises, Andy Allen suggests that 6 ft. between vines is too close under North Carolina vigor levels and would rather see vines spaced at 8 ft. apart.
Q: How much wine can one make from a ton (2000 pounds) of grapes?
A: Average production is about 100 gals/ton. Reds can get up to 110-120 gal/ton, whites aren't pressed as hard (otherwise you get harsher tannins from the seeds) and therefore don't have as high a juice yield as reds (90-100 gal/ton).