Whether you’re growing grapes to make your own wine or for some delicious summer snacks and preserves, it’s important to ensure the vines they grow on are healthy each and every year. The healthier the vines, the more fruit they’ll produce. Of course, getting healthy vines and fruit involves more than good soil and frequent watering and fertilizing. Although these three things are certainly important, the thing they need most is pruning. Pruning not only helps shape the vines, but it also optimizes air flow, which is essential for their health.
Basic Principles to Keep in Mind
Grape vines produce fruit on one-year-old wood. The green shoots the vines produced each year will often turn brown by the end of the season, by which point they are considered one-year-old wood. While some of this growth will go on to produce flowers, much of it will only produce more shoots. In fact, grape vines tend to produce more wood growth than anything else to support fruit production. In order to produce more fruit, it’s essential to increase the amount of one-year-old growth on the vine, and that's where pruning comes in. Ideally, you’ll want to remove 70 to 90 percent of the year’s growth.
By pruning, you can also shape the vines as you wish and give them more structure. If you’re trellising your vines, then they'll usually consist of one main trunk flanked by two or four branches on each side. You’ll want to cut the growth back to just the primary trunk and branches and maintain its new shape for the following year. Practice balanced pruning to maintain the shape and health of each plant, and never prune two-year growth or older unless you’re trying to reshape or cut back a vine.
If it’s your first time pruning your vines, you may be nervous about cutting them back too much. Don’t worry — grape vines are actually hardy plants. In fact, most people don’t prune enough. If you want to have a hearty harvest of grapes next year, don’t be shy. Get out your shears and loppers, and start cutting away (at an upward 45-degree angle, of course). Prune dormant vines either in the late winter or early spring, but don’t do it when they’re frozen, as it can end up damaging them. If you think you’ve cut a little too much off or you’re not happy with the shape, you can always fix it next year. During the growing season (and especially in areas with short ones), you'll remove the leaves around the grape clusters to help the fruit get full sun.
Preparing for Pruning
To start, you’ll need loppers, pruning shears, and a pruning saw for old growth. The older the vine, the thicker and more established its woody parts will be, so you may need to use bigger and sharper tools on some of them. A good rule of thumb is to use the shears for growth that's less than half an inch in diameter and loppers for growth that's larger than a half-inch but smaller than two-and-a-half inches thick. The saw will handle all the larger stuff.
Before you start snipping, sterilize your equipment with isopropyl alcohol. If you're pruning more than one vine, you'll want to resterilize before cutting each one. Sterilizing your tools helps prevent the spread of disease. While you’re cutting, you should also take the time to remove diseased wood and assess the vines' leaves and shoots. Dispose of any diseased leaves in your trash can. Don't put them in your compost bin, as the disease might spread throughout it and contaminate your whole garden come growing season.
A few other notes: always cut at an upward 45-degree angle, and use green plant tape to secure your vines to the trellis. The green tape holds the vine to the trellis without hurting the plant or impacting its growth.
Special Considerations for the First Year
For first-year vines, your focus should be on establishing a trunk. If you’ve just received your grape vines, you'll want to select the shoots that looks the strongest and cut the rest of the plants back to them. Cut the would-be trunk back to about two or three buds above the previous spring’s growth. As the vine grows in the spring, you’ll want to tie it to the trellis for added support and remove any other shoots that may appear.
To give your vines some added strength, place a strong support stake close to the base of their trunks with a two-by-four or another strong piece of lumber. Hammer the stake into the ground so it’ll support the vines as they grow.
Pruning in the Second Year
In the second year, you’ll cut the main trunk back to right below the bottom horizontal support. When the shoots sprout in the spring, you'll want to choose the ones that look the strongest and tie them to your trellis. Then, cut the rest of the vines back.
In the Third Year and Beyond
By year three, your grape vines will be well-established and will typically produce quite a bit of fruit. During the fall and winter, you’ll focus on thinning the shoots that have grown. Try to target one shoot for every six inches of vine. Cut all the other shoots down to about six inches and remove any growth (including suckers) that has sprung from the main trunk or the roots. Your focus will be on maintaining each vine's shape and pruning for increased fruit production during the growing season.
Taming Old, Overgrown Vines
Taking control of an overgrown vine may seem intimidating, but it can be done with a bit of elbow grease. Cut the vines back to about five feet tall using a lopper or saw, depending on the size of the wood. Once the majority of the growth is gone, you’ll be able to pinpoint where to cut. Remove the canes that are small (i.e. pinky sized) or unlikely to produce grapes. Remove any leaves or vines that show signs of damage.
While you should remove any growth that's older than two years, it’s more prudent to remove it only if it's not likely to produce fruit. If you’d like to shape the vine, choose at least two but at most four of the younger canes, and wrap masking tape around them so you can get back to them later. These are canes that will produce fruit next year. You’ll want to remove all the other canes.
Once you’ve removed the unwanted canes, you can turn your attention back to the younger canes you selected earlier and prune the vines. Count 10 to 15 buds above the base of the vine and cut at an 45-degree angle. If you spot any suckers or unproductive shoots, pinch or cut them off.
While You Have Your Loppers Out
While you’re pruning your grape vines, you can also prune nearby trees and shrubs well so your vines can enjoy lots of sun during the growing season. You’ve worked hard grooming your vines — so make sure they have enough sun to thrive.