Information: Pruning

For most grape vines you will need just one tool, a good pair of secaturs (hand-held pruning shears). Get a GOOD brand, not just a cheap knock-off from the local multi-store. If possible, order from a professional nursery supply company. My personal favorite is Felco.

The advantages of their pruners are: 1.) The type of action of a blade sliding past an opposing surface. When the blade is sharp, cuts are clean with no ragged or crushed ends, such as can happen with the type where a blade strikes an anvil. 2.) All parts are replaceable and the blade can be taken off for easier sharpening. Also, the steel is hard enough to hold an edge well. 3.) Felco has several styles, including one for left handed people, and my personal favorite, the type with a rotating handle that reduces strain of cutting.  When larger cuts are needed, use a short pair of lopping shears, or a small folding pruning saw.

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For most grape vines you will need just one tool, a good pair of secaturs (hand-held pruning shears). Get a GOOD brand, not just a cheap knock-off from the local multi-store. If possible, order from a professional nursery supply company. My personal favorite is Felco.

The advantages of their pruners are: 1.) The type of action of a blade sliding past an opposing surface. When the blade is sharp, cuts are clean with no ragged or crushed ends, such as can happen with the type where a blade strikes an anvil. 2.) All parts are replaceable and the blade can be taken off for easier sharpening. Also, the steel is hard enough to hold an edge well. 3.) Felco has several styles, including one for left handed people, and my personal favorite, the type with a rotating handle that reduces strain of cutting.  When larger cuts are needed, use a short pair of lopping shears, or a small folding pruning saw.

The first, most basic reason for pruning of grapes is to regulate the amount of the crop. This, in turn affects the quality and insures uniform, annual production.  A vine produces it's crop from buds laid down in the previous year's new growth. That means that in the winter, all the buds on all the new canes already carry flower buds which can bloom and become clusters of grapes. If you carefully open and dissect a bud, you will actually find a tiny little compressed shoot and flower bud clusters. Leave a lot of buds and there will be a large crop, but too many buds means more fruit than the vine can handle properly. Here's what happens when you leave a vine unpruned or prune it too little:

First, at bloom time, if there are too many flower clusters, available food (carbohydrates) is spread among too many flowers. This means fewer flowers in each cluster get the energy needed to allow them to set and start developing into berries, or they get only enough to develop into undersized berries.. With fewer berries per cluster the clusters are straggly or loose instead of well-filled or even compact.

Additionally, there are many more clusters than usual, so the overall weight of fruit is still higher than normal. This fruit is competing with new shoots and undeveloped leaves for the food stored in the vine, that being the only source the vine has until the new leaves have matured enough to make carbohydrates. This means the fruit has to wait until there are sufficient mature leaves to make all the carbohydrates needed by both the new growth and the fruit. But by then, it is too late to improve the fruit set, and there isn't enough growing season left for the new shoots to develop size and vigor, and the berries get don't get needed sugar to ripen until much later than normal, if they get enough at all.

If the variety ripens late normally, overcropping can make it so late it won't ripen before frost. Even if the fruit does ripen, it may taste flat, because the acid in the berries keeps decreasing as part of the ripening process, no matter how long it takes for the sugar to build up. This means that on an overloaded vine, it can take so long for the sugar to build up that by the time it is high enough, the acid has dropped too low and the fruit tastes flat and insipid. Finally, the fruit color on an overcropped vine usually doesn't develop well, making it both unattractive and lacking pigment for wine, juice or jelly.

Meanwhile, because the new shoots got little food, they developed fewer buds with smaller flower clusters in them, setting up the vine for a sparse crop the next year. In short, an unpruned vine may have more fruit, but it's quality is likely to be so poor it's hardly worth using, and it insures that the next year's crop will be quite small.

Even more important, when the fruit has to stay on the vine longer than usual to ripen, the energy it takes is diverted from helping the new growth harden off and get ready for winter. This can mean more dieback of the vine and it's canes, possibly leaving the vine in a weakened state or even killing it, by the time spring arrives. Even in mild winters, poorly ripened wood is apt to fall prey to disease and die back to older wood.

The year after a vine is overcropped, it produces very few clusters, though their quality of may be surprisingly good. That's because so few fruit buds were laid down the year before, due to the overcropping of the vine. Now, with so few clusters, the ratio of leaves to fruit is higher and the few clusters there are get sweeter, the berries get bigger, and the crop ripens earlier. Trouble is, with a smaller crop, the vine also has energy enough to produce more new growth, including more fruitful buds, which means another large crop looms ahead for the following year. And because there is also more food to allow the wood to harden off better, the odds of all the new growth surviving are increased. In other words, the stage is set to repeat the boom-bust cycle again.

Unpruned vines can reach a sort of equilibrium and stop the up and down cycle, but the fruit rarely as good as on a pruned vine, since it still doesn't get the amount of light or air circulation it might, due to the mass of old growth surrounding it. If all you wanted to do was keep crop production regular each year, you could do it without pruning, by picking off flower clusters early in the season, before bloom. This would adjust the crop so the vine wouldn't be overloaded, keeping the fruit quality high. Of course after a few years of doing it this way, the vine would be an enormous tangled mess - pruning is needed to keep the vine under control at the same time it adjusts the crop.

Let's stop and explain a little of what is happening here. The same buds which produce fruit also produce shoots that bear leaves. On a pruned vine the smaller number of buds means a much smaller number of new shoots to start growth in the spring, and until the leaves on the new shoots are mature enough to produce food, the vine is living off stored reserves. Even then it takes a while before there are enough mature leaves to offset the drain on the stored food. For instance, a vine pruned to have only 24 fruit buds on it will have to grow for several weeks before the first new leaves are ready to produce food.

Meanwhile an unpruned vine will have at least ten times that many shoots, or 240 leaves producing food at the same time the pruned vine has only 24. Now, if the crop on the unpruned vine had been thinned so it has the same number of flower clusters as the pruned vine, each flower cluster will have at least ten times as many leaves feeding it, early in the season, right at bloom time. This gives the unpruned vine a big jump on the pruned one early in the season. Eventually the shoots on the pruned vine get long enough to have as many productive leaves total as the unpruned vine, especially since the unpruned vine's shoots don't elongate much. So while the unpruned vine has the edge early in the season, but the pruned vine catches up. That is, the energies of the unpruned vine are divided among many more shoots, so each one may grow only a foot or so, while the pruned vine thrusts it's energy into fewer shoots, pushing them to much greater ultimate size. But the unpruned vine has the edge for the first part of the season, if the number of clusters is adjusted, giving it a much higher percentage of leaves to fruit early on. If regulating the size and quality of the vine's crop was the only reason for pruning grapes, the chapter would end right there, but other factors weigh against the advantages of leaving a vine unpruned. After crop regulation, the next most important reason to prune is to make the vine manageable and the fruit accessible. Unpruned vines can give good crops by just adjusting the ratio of flower clusters to shoots, but given room enough, plus sufficient nutrients, water and light, a vine can cover a large fraction of an acre. Letting a vineyard grow that way could be more than a little difficult to deal with.

You can do a lot with grape vines - they can be trained or guided to grow in a greater variety of forms, sizes and situations than any fruit tree or bush. Grapes can be grown in pots and kept to tiny sizes that bear no more than one or two clusters of fruit per year. At other end of the scale, at the University of California at Davis, a vine of the "Mission" variety of Vitis vinifera has been allowed to reach a size to cover a massive trellis of around a tenth of an acre and it produces at least a half ton of fruit per year. The vine could potentially grow to cover a quarter acre or more, but is restrained by pruning. It is by no means the largest of it's kind, either. There are records of old vines of "Mission" grapes in California that reached massive sizes. A vine planted in Carpenteria, California in 1842 produced eight tons in 1893 and had a trunk circumference of 9 feet. In England, the "Hampton Court" vine, the vinifera variety "Black Hamburg", has attained amazing size and production for being grown in a greenhouse, often yielding 2500 clusters a year. The form of a vine can be anything the grower dictates, from a single trunk growing in one direction, as the English sometimes use in greenhouse growing of grapes, to multiple trunks fanning out to all points of the compass, on arbors. Vine height can range from many feet high, as with the Italian "marriage of the tree and the vine" in which vines are trained into trees, down to methods of spreading a vine flat on the ground to take advantage of heat radiated from soil and rocks. In the latter case, this can be done to both protect grapes from late frost and to allow them to get enough heat to ripen in cold northern summers. In between are numerous forms that range from using the vine's own shade to protect the fruit from sun in hot climates, to systems used in high latitudes where sunlight has low intensity, where vines are spread out in ways to catch all available light. More on this further on.

Pruning helps the grower adjust the vine to the environment in other ways. Proper pruning can improve air circulation in the vine to cut down the likelihood of disease. Vines can be pruned so they will bloom later than usual, to escape frost. The right pruning and training system can make it possible to grow vines so they can be better protected from winter so that a variety that wouldn't survive a harsh climate on it's own can instead produce and bear where Nature would otherwise say "No".In short, pruning controls the size and form of the vine both for the convenience of the grower and for the vine to best adapt to it's environment.

One serious misconception is that there is a single "one-size-fits-all" system of pruning and training for all grapes in all situations. While some principles apply to the pruning and training of all grapes, trying to make one system fit every variety in every situation is a sure way to fail, wholly or partly.

How a vine is best pruned depends on two main factors: the system used to train the vine and the variety of grape, with each factor having an effect on the other. But no matter what system is used, they all are based on variations of two basic methods, spur pruning and cane pruning. The one thing all pruning and training systems have in common is that they all use one or the other (or rarely, both) of the same basic structures to carry the fruit buds. That is, fruit buds are borne on shoots that grew the previous summer, and those shoots, a.k.a. "canes" are pruned to different lengths to either become fruiting spurs or fruiting canes. A spur is generally recognized as a cane or shoot that has been shortened so it has from one to four buds, with 2 to 3 being the most common.

Fruiting canes may have from 5 to as many as 15 buds, with 10 to 12 the most common number. The difference between training systems is largely a matter of how long the spurs or canes are and how they are positioned, in relation to both the vine and to the trellis. The spurs or canes are replaced every year, while the older wood of the vine is basically unchanged, once trained into it's permanent form early in the vine's life.

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Is done on a vine trained to a permanent framework of two year or older wood with the fruit bearing wood - spurs with one to four buds each on them - spaced along the framework. The buds on the spurs produce the fruit bearing shoots every summer. In turn, most of those shoots are removed every winter with one of the lowest shoots on the old spur being cut back to become a new spur.(see illustrations). Spur pruning is probably the easiest system for the novice to prune. Once the spur positions have been established, pruning is little more than removal of unwanted canes, plus cutting back of the remaining shoots at the spur positions, and the old spurs help serve as a guide. In other words, just repeat what has been done the year before.

The common training systems using spur pruning are head-trained, spur-pruned vines (HTSP) and cordon trained vines. A HTSP vine is nothing more than a vertical trunk, usually tied to a post, with spurs radiating around the top 1/2 to 1/3 of the trunk, making the vine look something like a bush or dwarf tree. The system is easy and cheap to establish because untreated wooden posts can be used as supports and by the time the wood rots away, the vine's trunk has become rigid enough to support itself. However, vines trained this way tend to yield less because they are restrained to a smaller size than they are capable of reaching, so they don't carry as many fruiting spurs as they could.

The clusters are all produced near the trunk and tend to get tangled in the shoots, making them harder to pick and more prone to damage. And the dense tangle of growth reduces air circulation and makes the interior of the vine a good place for disease to start, as well as making it hard to get spray into the area for treatment.

In the past, HTSP vines were common in the wine vineyards of California, but the system lost favor because of difficulties in caring for the vine and harvesting the fruit. The system is only suited to low to moderate vigor wine grapes with an open growth habit that keeps picking from being too difficult. Table grapes grown with this system may have poor appearance due to difficulty controlling disease, and tangling of the clusters in the vine that can crush and deform berries and make it difficult to pick them without damage.

The other important system using fruiting spurs is the cordon system.  In this method, fruit spurs are carried on permanent, horizontal arms extending from the trunk. Usually there are two arms, giving the vine a "T" shape, though other arrangements are possible. Each arm is usually three to four feet long and has up to six spur positions. While each position may start out with only one spur, as the vine matures and gains vigor, it may be able to carry more fruit and it's possible to additional spurs at each position.

How to add a new spur: When pruning spurs, there are usually at least two shoots coming out of the previous year's spur, assuming it was a two bud spur. If you were pruning the regular way, you would cut off the upper half of the old spur, and the attached shoot, then make a new spur by cutting back the remaining shoot to two buds. To get a new spur, simply leave both shoots, and cut each one back to become a new spur. Or, if you are lucky, there are often suckers near the base of the old spur and one of those can be cut back to become a new spur itself. Don't be in a hurry to add new spurs at every location - it's usually better to add only three or four spurs to the vine at first, then wait and see how it performs. If the vine carries the new crop load well with no sign of overcrop, more spurs can be left the next pruning season. Eventually, instead of a row of straight spurs lined up on the cordon arms, there may be two spurs at each location, arranged in a "V" shape.

While vines trained to cordons need full trellising, with wires, posts, wire anchors, etc., compared to HTSP vines, which need only untreated wood posts to start them out, the difference in production and fruit quality, especially with table grapes, is worth it. On cordon trained vines, clusters are spaced evenly and regularly, usually hanging just below the cordon arms where they can be harvested easily, and where they are protected by the foliage from sunburn. Growth is spread evenly along the wires, so air circulates through the vine well, and spray penetrates more uniformly than with HTSP vines. A vine properly trained to cordons is very easy to prune and even novice pruners can handle it with only a bit of instruction. This is because the pruner can see how the vine was pruned the previous year by the appearance and location of the spurs and just has to simply repeat the process, while removing excess shoots that have arisen outside the spurs.

There are several variations of the cordon system. including the Geneva Double Curtain and forms that have up to four arms vertically - two upper and two lower. The Geneva Double Curtain (illustration) is an extremely productive system, though it has some disadvantages. If the variety is a vigorous one, the double "curtains" may be so dense as to create a "dead air" space between them where air circulation is restricted and spray doesn't penetrate readily.

There are so many different training systems that have been developed for commercial wine vineyards that it isn't possible to cover them here. Each is designed to make best use of light, help develop fruit buds, help ripen fruit, give better air circulation for disease control, etc. in a specific climate, site, and situation. Because of that, a would-be commercial grower should seek out systems from others in similar types of climate and site. A good place to start is to find out if your state has a grape grower's association. Ask at extension offices, or at your state land-grant college (state university, like Oregon State U., Iowa State U., etc.).

Remember, when pruning spurs, prune weak spurs heavily, vigorous ones very little -just the reverse of fruit trees. Try not to leave large wounds - vines don't heal over like fruit trees, and disease can enter large wounds more readily. It's sometimes better to leave stubs sticking out, which may eventually rot, than to cut a cordon arm or large spur off flush with the old wood and leave a big wound that won't heal over at all.

Systems like the Geneva Double Curtain are very efficient at producing large crop loads for the area they cover because the way the system allows the new shoots to hang downward, exposing the bases of the shoots to full sun, which increases the fruitfulness of developing fruit buds. Experiments at U.C. Davis showed that buds fully exposed to the sun became more fruitful (larger flower clusters and more clusters) so that the same number of buds gave a larger crop than similar vines whose developing fruit buds were shaded. More interesting, the extra crop didn't overload the vines - they were able to mature their crop as well as the vines with shaded buds. The drawback of the Geneva Double Curtain in some cases is that the "curtain" creates a dead air space in the center of the vine that fosters disease. Use of the system in Oregon with vigorous vinifera wine grapes increased yield, but powdery mildew became rampant and the accompanying decrease in fruit quality offset any gain in crop size.

In cold climates, one variation of the cordon trained vine is a straight trunk trained diagonally, with spurs on the upper half of the trunk. By being trained diagonally, the vine is easier to lower to the ground to be covered up for winter protection. (see section on cold climate viticulture for more).

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Various forms of this type of system are used extensively in modern commercial wine vineyards for a number of reasons, covered further on. The version most home growers will recognize is the old "Kniffen" system, both the two cane "umbrella" Kniffen and the four cane Kniffen.

Cane pruning, as the name indicates, relies on canes rather than spurs, to produce the fruit. Canes may have as few as 5 buds to as many as 15. Cane systems often require more wires or other supports than spur systems, and pruning them takes more experience and decision making. However, canes are a more flexible system than spur pruning and they allow more year-to-year variation in the amount of fruit buds left on the vine. If you want to increase the number of fruit buds on spurs for greater crop, you can usually only add about 12 or so per season. With cane pruning you can add as many canes as there are available, possibly even doubling the amount of fruit buds over the previous year.

The main difficulty with cane pruning is that it takes more experience to learn how to choose which canes to cut back to become the replacement spurs and which to leave as fruiting canes, as well as deciding how many canes to leave. New growers often fail to remove enough wood, letting the vine overcrop, with the results discussed earlier. 90 to 95% of the previous season's growth should be removed in proper pruning.

Several systems have been developed to help a grower determine if enough wood is being removed at pruning time. One method is to weigh the wood removed from the vine. Pruning a vine this way, based on its growth in terms of the amount of one year old wood it produced the previous growing season, is called balanced pruning. It is used to determine the fruiting capacity of a vine for the coming season by weighing the wood removed at pruning time. Common balanced pruning formulas include: Vitis Vinifera - 20 buds for the first pound of prunings, plus another 20 buds for each additional pound of prunings, up to a maximum of 60 buds. For French or American hybrids - 20 buds (for the first pound), plus another 10 buds/ additional pounds of prunings, up to a max of 50 buds. Native American varieties - 30 buds (for the first pound) plus another 10 buds per each additional pound of prunings, up to a max of 60 buds.

Another is to count the buds on the pruned vine. Both methods depend on how well the grower knows the vines. Weight of wood depends a lot on health of the vines, soil, climate, growing year, crop load, and more. A novice setting pruning standards based on weight of wood may find it awkward as it is necessary to prune the vine and weigh cuttings a little at a time or you may find that when you get the total weight of the prunings, you haven't left enough wood on the vine to leave enough fruit buds by the formula. Of course it also means more work as you have to take time to cut up the wood and either carry it to a scale, or set one up in the vineyard. Either way adds time and work to the job. Pruning by counting the number of fruiting buds is the easier method for home growers or anyone who stays close to their vines. When you have started from a cutting or a new vine and followed it through training and into bearing, you get to know it well enough to tell if you have left too many buds, or not enough, by the quality of the fruit and how the vine grows.

How many buds SHOULD you leave? That is mainly a matter of your climate, soil, the age of the vine, and the variety of the grape(s) you are growing. A good basic rule is: First bearing year. Leave 24 buds (two cordon arms with 6 spurs each, or two canes with twelve buds each) for the first bearing year, and remove at least half the crop, just after fruit set. Second bearing year - still 24 buds, but leave the full crop. Third bearing year, leave 36 buds (three canes or an extra bud at each spur on the cordon), etc. In other words, if the vine is growing well, ripening it's crop well, and seems healthy, add another 12 buds each pruning season, up to a maximum of about 60. The two main exceptions to the 60 bud limit is if the variety is extremely vigorous and can clearly carry more crop, or if the clusters of the variety are small and the only way to get a reasonable weight of crop is to leave more buds to get more clusters. Some of the French Hybrid wine grapes, such as Marechal Foch, for example, often have small clusters and the only way to get a reasonable crop is to leave as many as six canes with 12 to 15 buds each per vine. Though even in that case, the vines must be on fertile soil. Vines on poor soil may not be able to carry large crops, or the fruit quality may be lowered with too large a crop.

It should be noted that while lower fruit quality is a sign of overcropping, it is possible to have the quality of wine grapes decreased by too much crop, without actually overloading the vine. That is, the fruit ripens well enough, and on time, but subtles of flavor and character in the wine can be lost. A friend with a vineyard did such an experiment in which he left three canes on some vines and two canes on others. The fruit on both ripened well, and on time, but the wine from the two-cane vines had flavor that was more intense, with extra subtle undertones to it. These are the sorts of results that are personal and each grower must try different crop levels to find what is best in a given area, and what suits a particular taste.

When you have selected the canes you want to leave for fruit.

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For most grape vines you will need just one tool, a good pair of secaturs (hand-held pruning shears). Get a GOOD brand, not just a cheap knock-off from the local multi-store. If possible, order from a professional nursery supply company. My personal favorite is Felco.

The advantages of their pruners are: 1.) The type of action of a blade sliding past an opposing surface. When the blade is sharp, cuts are clean with no ragged or crushed ends, such as can happen with the type where a blade strikes an anvil. 2.) All parts are replaceable and the blade can be taken off for easier sharpening. Also, the steel is hard enough to hold an edge well. 3.) Felco has several styles, including one for left handed people, and my personal favorite, the type with a rotating handle that reduces strain of cutting.  When larger cuts are needed, use a short pair of lopping shears, or a small folding pruning saw.

While you are at the mercy of Nature with respect to frost on most fruit bearing plants, the right pruning can give leeway with grapes.

Here is the method:

Delayed pruning to delay bud break.

If a grape cane is left unpruned, the buds at the ends will push before the ones farther down and the upper buds will delay the lower buds by a few days to as much as a week or more. Taking advantage of this is just a matter of timing your pruning.

1. At the usual winter pruning time, remove only those canes that will not be used for fruiting or as a source of spurs - suckers, undersized canes, etc. Leave everything else unpruned.

2. In the spring, when buds are starting to push, wait until the buds on the ends of the canes you left are swelling enough that the new leaves become visible just opening out from the bud. At this point, go through and pruned those remaining shoots back to fruiting canes or spurs.

If you compare these late pruned vines to ones that were pruned completely at the usual time in winter, you will see that the buds on the winter pruned vines are visibly farther along, at least a week ahead of the ones on the spring pruned vines. But the buds on the spring pruned vines are still tight enough to be able to withstand frost that can kill the unfurling buds on the winter-pruned vines. And though the late-pruned vines will open their buds later, they will ripen their crop at the same time as vines that were pruned completely at one time, in winter.

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For most grape vines you will need just one tool, a good pair of secaturs (hand-held pruning shears). Get a GOOD brand, not just a cheap knock-off from the local multi-store. If possible, order from a professional nursery supply company. My personal favorite is Felco.

The advantages of their pruners are: 1.) The type of action of a blade sliding past an opposing surface. When the blade is sharp, cuts are clean with no ragged or crushed ends, such as can happen with the type where a blade strikes an anvil. 2.) All parts are replaceable and the blade can be taken off for easier sharpening. Also, the steel is hard enough to hold an edge well. 3.) Felco has several styles, including one for left handed people, and my personal favorite, the type with a rotating handle that reduces strain of cutting. When larger cuts are needed, use a short pair of lopping shears, or a small folding pruning saw.

Eventually, you are going to have to prune a neglected arbor or vines that weren't trained right to start with, or have been left unpruned for a long time. The vines will have a mass of dead and tangled shoots with most of the new growth being too small to be of any use as new fruiting canes, and in the wrong place to be pruned as fruiting spurs. Chances are good the arbor or trellis will be in disrepair and need work, as well. Here are some options:

If you see a useable vine structure or a good trunk under all the growth, you may wish to take the time to sort it out. In most cases, though, you will spend a long time cutting out masses of old growth while hunting for the few shoots usable as new fruiting wood. At best, you will probably get a partial crop that year. And it will likely take at least two more winters of redirecting new shoots until you have something that works. At that, the new fruiting wood is apt to be badly located and probably convoluted at best.

If the trunk of the vine is straight, or is otherwise healthy, you may be able to shortcut the process by cutting everything off back to the head of the trunk - the point at the top of he trunk where the canes or cordonts originate. You will have no crop that season, but you can easily train the new shoots that come out as canes or new cordons to bear a full crop the following year.

In many cases, however, the vine will likely be such a mess of old growth and oversized wood, combined with the twisted, multiple trunks that result from amateur training attempts, that the simplest way to prune it is with one quick cut, through the base of the trunk(s), one to two inches from the ground. No, that doesn't mean you should kill the vine, or will have even
harmed it by doing that. Unless the vine was sick in the first place, it will sprout back and refill the arbor/trellis in one season, given the chance. The new growth will usually resume bearing the very next year. Indeed, this is one of the advantages grapes have over fruit trees. If a tree is killed by cold weather, it may well be lost altogether, or if it isn't it will take at least two or three years to re-grow sufficiently to resume production. An otherwise-healthy vine killed to the ground by cold will usually re-grow completely in one season, able to resume full production the following year.

With the vine cut off, you can now make necessary repairs to the arbor/trellis without having to work around a tangled vine and you will have the chance to train the vine up in a better form than it had to begin with, as though you were training a new vine (which is what it is, from the ground up).

The only time this may present a problem is if the vine was grafted to a rootstock, but the odds of such a vine being planted to an arbor are small. Grafted vines are usually encountered only in commercial vineyards. Even there, the union between the fruiting variety and the rootstock is usually easy to spot as the rootstock will have different bark than the top, and there will be a distinct juncture between the two, usually a visible swelling or knob. Further, the vines in a commercial vineyard, even when neglected will very likely still have a good basic structure and can be brought back to fruitfulness without having to resort to such drastic pruning.

After an own-rooted vine has been cut off so drastically, soil should be mounded around the base of the shoots as they grow. Because grapes are not able to heal large cuts the way trees do, growing new bark over the wound, a large cut-off stump may rot out in a few years. By putting earth over the base of the new shoots, they will root and establish a separate root system long before the stump rots down into the old roots.

Just be sure that if you are doing the work for someone else, you explain it in advance, or at least be sure the person isn't fanatical about the vine, doesn't have a weak heart and isn't prone to being a homicidal maniac - they'll think you MUST have killed the vine when you hack it off next to the ground.

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"The shoots on my vines grow out where I don't want them in the summer. Can I cut them off?"

Removing green growth from a vine should be taken on a case-by-case basis. That green, new growth is often producing food the vine needs to help the fruit ripen and to mature the wood for winter. Further, cutting the shoots may stimulate shoots at the end of the cut cane to start growing, keeping the vine active late in the season when it should be getting ready for cold weather.

Additionally, if a vine is growing so much late into the summer that you do have a big mass of green growth that seems to be excessive, enough to make you WANT to do some summer pruning, it's likely the vine is getting water and fertilizer too late into the season. Better to cut off the water and fertilizer to make the vine slow down than to cut it.

Finally, if you prune shoots in the summer too much, you may find your self short of good, long canes at dormant pruning time - they were shortened prematurely.

Of course, there ARE times when the vine is just too big, either because it's a very vigorous variety, like "Niagara", or you have no control over the moisture or fertility of the location where it is growing, and you have to do something to keep it from overrunning it's space.

If you must cut green shoots, a compromise is to cut them back to the point on the shoot where the leaves are half the size of mature size. Until a leaf reaches that size, it isn't producing food for the vine, so it will be missed less than mature leaves that are feeding the vine.

In general, however, it's safest not to cut or remove green shoots from the main structure of the vine. This insures the vine will have it's food-producing capacity unimpaired. The exception is in the removal of suckers from the trunk, which should be taken off as early as possible. 

Additional notes: I've had people ask if they should cut the shoots off beyond the clusters to make the vine put energy in the clusters.

Definitely NOT.

This not only doesn't put extra energy into the clusters, it reduces the amount of foliage that the vine would otherwise use to make food FOR the clusters. Plus stimulating too  much vegetative growth at what might be the wrong time.

Should I clip back leaves, to allow nutrients and sunlight to get to the grapes?

No.

The vine takes care of getting nutrients to the fruit, and most varieties don't need to be in full sun to develop color. More sun on the fruit may improve the color in some cases - make white grapes more golden, for instance, but for that you only need to remove a few leaves that are directly shading the cluster, and don't do it until ripening has started.

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For most grape vines you will need just one tool, a good pair of secaturs (hand-held pruning shears). Get a GOOD brand, not just a cheap knock-off from the local multi-store. If possible, order from a professional nursery supply company. My personal favorite is Felco.

The advantages of their pruners are: 1.) The type of action of a blade sliding past an opposing surface. When the blade is sharp, cuts are clean with no ragged or crushed ends, such as can happen with the type where a blade strikes an anvil. 2.) All parts are replaceable and the blade can be taken off for easier sharpening. Also, the steel is hard enough to hold an edge well. 3.) Felco has several styles, including one for left handed people, and my personal favorite, the type with a rotating handle that reduces strain of cutting.  When larger cuts are needed, use a short pair of lopping shears, or a small folding pruning saw.

In a small home vineyard, it is often simplest to collect the prunings and chip or shred them, especially if you feel there is disease in them. They can then be composted to kill the disease and the compost returned to the vineyard later.

In my own vineyard, I find it easiest to leave the prunings in the row middles and go over them with a flail mower. By setting the tractor on low speed, the mower runs fast enough with enough power to grind most canes up completely. By early summer, there is little or no sign of anything left. With a very few vines, it's possible to cut the canes up into short pieces with a hand pruner and leave them in the row to break down.

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