\”Pruning is essential to ensure that wine grapes reach their optimal size and flavor.iStockphoto/Thinkstock
At the end of a taxing week — or day — a glass of wine can certainly help the sunrise-to-sunset cares slide away. As you slowly savor each sip, you\’ll discover different layers of flavor — the velvety chocolate sensation of a petite verdot; the deep, earthy tones in a shiraz; or the crisp, citrus tang of a sauvignon blanc.
No matter what wine you prefer, there is one element common to them all: the prune. No, we\’re not talking dried plums here. We\’re talking about the process of managing the vine by removing excess branches, or canes, and foliage.
Pruning keeps grapevines healthy and productive. Believe it or not, this physical process influences the taste and quality of the wine in your goblet: When, how and to what extent the vine is pruned affect grape yield, and the timing and method of pruning can enhance certain aromas and alter the acid content of the wine.
Read on to learn about the pruning practices that help get the most enjoyable end product.
Contents
- Pruning is Necessary
- Timing is Everything
- Take a Balanced Approach
- Technique Matters
- Use the Right Tool for the Job
5: Pruning is Necessary
Crisp breezes freshen the air. Sunlight caresses grapes, making them glow. Plump with juice, the generous bunches pull toward earth. It\’s going to be a glorious harvest.
Ah, if it were only so easy. Before you drink the wine, you have to grow the vine, and annual pruning is an essential step to enjoying healthy, flavorful grapes at fall harvest.
"The first year we pruned, we were very nervous," said Doug Paul. He and his wife, Sharon, own and operate Three Sisters Vineyard and Winery in the north Georgia mountains. "Most beginning wine growers don\’t prune enough."
Pruning means cutting off canes, or branches, that could produce grapes. Giving up part of your crop is a hard thing for any gardener to do, but if you don\’t prune, the vines produce more grapes than they can fully support. By removing excess canes, you let the plant concentrate its energy in the selected canes, which ensures the grapes that are allowed to grow reach their optimal size and flavor. Removing damaged or diseased plant parts is another important function of pruning.
Next up, learn when to prune your vines.
Bountiful Harvest
The U.S. produced almost 6.88 million tons of grapes in 2010.
4: Timing is Everything
\”Using a demonstration vine, vintner Doug Paul points out a leader cane. Originating from the trunk of the vine, this cane could be trained horizontally to replace the older cordon.Photo courtesy Heather N. Kolich/Three Sisters Vineyard and Winery
Pruning has two phases: winter vine thinning and summer foliage trimming. With winter pruning, your goals are to eliminate crowding, select growth points for this year\’s crop and set the stage for next year\’s crop. Late winter to early spring is the best time for vine pruning — when the worst winter weather is behind you but before spring blooms appear. At Three Sisters Vineyard, pruning begins in December and wraps up by early March.
"Grapes store energy in their root balls," Paul said. "You don\’t want to drain off energy too early."
Vines pruned too early are also more susceptible to fungal disease. Fall rains splash fungal spores up from the ground onto the plant, where fresh pruning cuts are susceptible to infection. Summer pruning involves hedge trimming the leaves.
"During the summer growing season, leaves provide shade around the fruit, but within the last month before harvest, you want to remove some foliage," Paul explained. "You also want to keep the vines off the ground."
Most wine grapevines are grafted onto disease-resistant root stock. If vines touch the ground and begin to root, they lose the benefit of the hardier root stock and become vulnerable to disease.
See how much to prune on the next page.
3: Take a Balanced Approach
Your dormant vine may look like a dense tangle. After pruning, it\’ll look lean and orderly. "Pruning is a part of the control of the vine," said Paul. "You don\’t want the vine to take over."
On mature vines, the number of buds to keep depends on how much the pruned canes (branches) weigh. If you prune one pound (0.5 kilogram) of canes from a vigorously-growing varietal, you can leave 30 growing nodes — budding points in joint-like rings along the canes — on the vine. On slower-growing varietals, limit the vine to 20 nodes. For every additional pound (0.5 kilogram) of pruned canes, add 10 nodes.
Pruning is also important for disease control. By removing injured or infected plant parts, you encourage new growth and mitigate the spread of disease. Once growth begins, a properly pruned vine is open to sunshine and air flow. These healthy-growth essentials encourage vigor in the vine by facilitating photosynthesis and deterring many diseases and pests.
Patience Pays
The first two to three years after grapevines are planted are devoted strictly to establishing a vigorous root system, a straight trunk and training two arms, or cordons, of the vine to grow horizontally on the trellis. Unfortunately, that means removing all grape buds.
2: Technique Matters
\”A preserved demonstration vine at Three Sisters Vineyard and Winery shows two long canes with several nodes and the shorter, one-node spurs.Photo courtesy Heather N. Kolich/Three Sisters Vineyard and Winery
In general, vines of American grapes grow in flowing curtains that weep downward like a willow tree, and French grapevines grow more upright, like tomato vines. For all vines, new growth originates from shoots. Shoots grow from nodes (the areas of buds along the branches of the vines). Canes are branches that grew the previous year from a one-node spur on the cordon, the horizontal arms of the vine.
When you prune, you want to keep evenly spaced canes for growing the current year\’s crop, and about twice as many spurs to grow canes for next year\’s crop. French varietals are pruned to remove all growth points that aren\’t on the top of the cane. Because American vines grow downward, growth points are allowed to emanate from the top, sides and bottom of the horizontal cordon.
To begin winter pruning:
- Start at the trunk and move outward, removing dead canes.
- Next, remove canes that branch from another cane. Keep canes that originate from the cordon.
- Count your remaining canes. The number you keep on each cordon depends on varietal and maturity.
- Select healthy, evenly spaced canes for this year\’s growth. Trim each to three to five nodes (depending on varietal), leaving 1/2 inch (1.25 centimeters) of cane below the last node.
- Select evenly spaced spurs. Prune them to one node extending from the cordon.
- Cut extra canes flush with the cordon.
You can\’t prune vines without the proper tools, so read on to the next page to learn about them.
1: Use the Right Tool for the Job
\”Sharp pruning blades and cuts that are flush with the cordon help pruning wounds heal quickly.Photo courtesy Heather N. Kolich/Three Sisters Vineyard and Winery
Pruning tools are very simple: You need a pair of sharp, heavy-duty pruning shears — secateurs if you want to impress friends with your French. While there is vine pruning machinery, it\’s generally considered pre-pruning equipment. Driving between rows, it embraces vines with two side blades and a top blade, chopping canes as it goes. To get a satisfactory crop, you\’ll need to do a second pruning by hand.
"You really need to spend time with the vines," said Paul, who also pointed out that the hilly terrain of many vineyards isn\’t suitable for pruning machinery.
Keep your pruning blades sharp, clean and lubricated to reduce injury to vines. Some growers dip blades in a solution of one part bleach to nine parts water between cuts to prevent spreading disease. You can also wipe the blades with rubbing alcohol.
Grapevines are long-lived perennials, and with proper pruning and care, they can thrive for decades.
Learn much more about wines and winemaking on the next page.
Wine Pruning Facts: Lots More Information
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Sources
- Chapman, Dawn, et al. "Sensory attributes of Cabernet Sauvignon wines made from vines with different crop yields." American Journal of Enology & Viticulture. 55, 4, 3025. 2004. (June 28, 2011) http://wineserver.ucdavis.edu/pdf/attachment/7sensory%20and%20crop%20level%20.pdf
- Friend, Adam and Michael Trought. "Delayed winter spur-pruning in New Zealand can alter yield components of Merlot grapevines." Australian Journal of Grape and Wine Research. 13, 3, 157. 2007. (June 28, 2011) http://wineserver.ucdavis.edu/pdf/attachment/156%20delayed%20pruning%20and%20yield.pdf
- Cobb County, Georgia, Extension Service. "Gardening Tips for March." March 2011. (July 3, 2011) http://www.caes.uga.edu/extension/cobb/anr/Documents/gardeningtipsMarch2011.pdf
- Hodgen, Donald A. "U.S. Wine Industry–2008." U.S. Department of Commerce. June 20, 2008. (June 29, 2011) http://trade.gov/td/ocg/wine2008.pdf
- Kissack, Chris. "Vine Training Techniques." The Wine Doctor. (June 28, 2011) http://www.thewinedoctor.com/advisory/technicaltraining.shtml
- Knopf, David. "Washington\’s Apple Production Forecast Up 5 Percent from 2009; Grape Production Forecast Down 6 Percent From Previous Year." National Agricultural Statistical Service. Oct. 8, 2010. (June 29, 2011) http://www.nass.usda.gov/Statistics_by_State/Washington/Publications/Current_News_Release/appgrape.pdf
- Nonnecke, Gail. "Pruning, Training, and Grape Canopy Maintenance." Iowa State University Department of Horticulture. Jan. 26, 2002. (July 3, 2011) http://viticulture.hort.iastate.edu/info/pdf/prunecanopy.pdf
- Paul, Doug. Wine grower and vintner, Three Sisters Vineyard & Winery, Dahlonega, Georgia. Personal interview. July 2, 2011.
- Weber, E., et al. "Double pruning of grapevines: A cultural practice to reduce infections by Eutypa lata." American Journal of Enology and Viticulture. 58, 1,. 2007. (June 28, 2011) http://wineserver.ucdavis.edu/pdf/attachment/95%20double%20pruning%20and%20eutypa.pdf
