Grape Growing In Tennessee

planted in fall or early winter maysuffer root injury or death in theevent of a prolonged cold periodshortly after planting. If plantinglater than early April, hot, dry conditions may occur that could reduce plant growth or even causeplant death.Since vineyard establishmentcan be fairly expensive, and sincea properly maintained vineyardwill live and fruit for many years,it is very important to purchasehealthy plants of the correct variety. Therefore, purchase plantsfrom reputable nurseries. As longas the vines are properly cared forin the nursery and during shipping,it is not necessary to purchasethem from local nurseries. Vigorous, one-year-old plants are best.Once plants are received, take careto prevent roots from drying out,freezing or overheating.The number of plants neededto supply fruit will vary considerably, depending on the use of thefruit and the number of people whowill be consuming it. Calculate thenumber of vines needed based onthe assumption that each matureplant will yield about 15 pounds offruit (25 to 35 pounds for a maturemuscadine vine) and that about 15to 20 pounds of fruit are requiredto give about one gallon of juice.Realize that these figures are onlyrough estimates and that severalfactors may influence them.Space grapevines about 8 feetapart in the rows. This spacingmay need to be increased to about10 feet for vigorous varieties set onfertile soils, or reduced to 6 feet forweak-growing varieties planted onless-fertile soils. For muscadines, aspacing of 16 to 20 feet apart inrows is suggested. The distancebetween rows will depend on thesize of the equipment being used tomaintain the vineyard, the lay ofthe land (extra distance betweenrows may be needed on steeperslopes) and the type of trellis constructed to support the vines. Commercial grape growers generallyspace rows 10 to 12 feet apart. Donot space rows less than 6 feetapart, as mutual shading amongrows may become a problem.(Diagram 3. Suggested Spacingsfor Grapevines). Table 1 shows thenumber of vines needed per acre atseveral in-row and between-rowspacings. To calculate the numberof vines needed per acre, multiplythe distance between vines in arow by the distance between rowsto find the square feet of space foreach vine. Divide this number into43,560 (the number of square feetin an acre) to get the number ofvines per acre.8 - 10 ft. between vines in a row10 - 12 ft. between rowsAmerican Bunch, French-American Hybrids,V. vinifera and Seedless Grapes16 - 20 ft. between vines in a row10 - 12 ft. between rowsMuscadinesDiagram 3. Suggested Spacings for Grapevines

Table 1. Number of Vines per AcreDistance between rows8 feet10 feet12 feetDistancebetweenvines ina row6 feet9077266058 feet68054445310 feet54443536316 feet34027222620 feet272217181vines/acreExample: 8 feet between vines in a row x 10 feet between rows 80square feet per vine. Divide 80 into 43,560 to get 544.5 vines per acre(round off to 544 vines.)Inspect vines upon receipt tobe sure the roots have not driedout, frozen or overheated. Healthyroots should feel firm, not spongyor hard and brittle when squeezed.You should be able to bend theroots some without breakingthem. Cutting through the exteriorof a root should reveal white tissue. If the interior of the root istan to brown, the roots have beendamaged and plant survival is aptto be poor.Store vines in a cool area.Take care to prevent the rootsfrom drying out, freezing or becoming too hot. If properly stored,vines may be kept in the shippingbundle for several weeks beforeplanting.Soak vine roots in water for acouple of hours prior to planting.Take care to prevent the rootsfrom drying out during planting.Inspect the root system beforeplanting. Prune off broken, dead,diseased or insect-infested roots.Do not prune the root system anymore than is absolutely necessary.Grapevines propagated fromcuttings or layering should beplanted as deep as they were set inthe nursery. Dig holes deep enoughand wide enough to accommodatethe root system without having tobend roots to fit (Diagram 4A.Planting an Own-Rooted Grapevine). Grafted grapevines shouldbe set with the graft union justabove the soil line (Diagram 4B).Set the vine in the hole, spread outthe root system and work soil inaround the roots to eliminate airpockets. Once the soil has coveredthe root system, tamp it down tofurther assure good root/soil contact. If the soil is dry, pour water inthe hole before completely fillingthe hole. Fill the hole with soil tothe same level or slightly higherthan the surrounding ground. If adepression in the soil is left atplanting, it should be filled beforegoing into the first dormant season.Freezing and thawing of water indirect contact with the trunk coulddamage it.DO NOT add soil amendments such as peat moss, sawdustor manure to the soil being used tobackfill the hole. Such a practicesciongraft unionrootstockDiagram 4A. Planting anOwn-Rooted GrapevineDiagram 4B. Planting aGrafted Grapevine

creates a “flower-pot” effect,which discourages root growth intothe surrounding soil. The more restricted the root system of thegrapevine, the more susceptible thevine will be to drought, flooding orimproper fertility. Do not put fertilizer in the hole because plantroots may be injured or killed bydirect contact with high amountsof certain fertilizer materials.Pruning and training are twoseparate practices that play veryimportant roles in the developmentand maintenance of grapevines.They influence light distributionthroughout the canopy, whichgreatly affects yields, fruit qualityand pest problems. Ease of management of the vines and the cropwill be impacted by pruning andtraining practices. Support wireson the trellis should be set at aheight that will make pruning,cluster thinning and harvest moreconvenient.Early in the life of the vineyard, pruning and training are usedtogether to build a vine of the desired size and shape. Once the vinehas filled its allotted space on thetrellis, annual pruning is used torenew fruiting wood, to promoteuniform light distribution throughout the canopy and to keep thevine from overgrowing neighboring vines. Pruning and training areparts of an integrated vineyardmanagement system in which eachpractice has an influence on thesuccess of all other cultural practices and on the overall crop.TerminologyArms — major branches ofthe trunk on which canes or spursare borne.Cane — a mature, woodyshoot after leaf drop.Cordon — extension of atrunk, usually oriented horizontallyalong a wire. Fully developed cordons can bear spurs and canes.Cordons may extend in one or twodirections from the trunk. They areretained for several years.Pruning — removal of partsof a plant. It is done to regulatecrop size and fruit quality. Pruningalso is used to determine the quality, quantity and location of vegetative growth. The two basictypes of pruning for grapes are 1)cane renewal (cane replacement),in which canes that fruited the previous year are removed and somecanes that grew the previous yearare selected for fruiting in the current year, and 2) spur pruning,where short canes that fruited theprevious year are removed and replaced with spurs on the cordon asa site for fruiting and shoot growththe current year. Pruning should bedone every year of the vine’s life.Shoot — green growth from abud on a cane, spur, cordon, arm ortrunk. A shoot always bears leavesand tendrils and may also bearfruit. In the fall, a shoot maturesand drops its leaves. It is thencalled a cane.Spur — cane pruned to a fewnodes (five or less). A renewalspur has one or two buds to produce canes at a particular locationon an arm or cordon. A fruitingspur is chosen to produce fruitingshoots.Training — development ofthe framework of the vine on thetrellis. Training impacts exposureof fruit and foliage to light, as wellas ease of management.Trunk — the semi-permanent,above-ground, vertically-orientedstem of a vine.The trellis of a vineyard shouldbe strong, long-lasting and requirelow maintenance. Its purpose is tosupport the foliage and fruit ofvines, thus allowing good light interception and ease of management. Trellis construction represents a major investment in bothtime and money.Two types of trellises are suggested for use in Tennessee vineyards. The vertical trellis uses twowires. The lower wire is situated at3 feet aboveground to enhancegood air circulation under thevines, and the top wire is at about6 feet aboveground (Diagram 5).The vertical trellis is used for thefour-cane Kniffin system, the umbrella Kniffin system and theHudson River umbrella system.The bilateral cordon system, avariation of the vertical trellis, usesa single wire to support the cordons and the crop. This wire maybe 6 feet aboveground for a highhead cordon system where newshoots grow down, or 3 feet inheight for a low-head cordon system where new shoots grow up.Movable catch wires may be usedto position shoots in either thedownward (Diagram 6A) or upward (Diagram 6B) direction. A

3 ft.Diagram 5.Vertical Trellis Design3 ft.2 ft.3 - 4 ft.16 - 24 ft.Before pruningCordonsDiagram 6A.High-Head BilateralCordon SystemAfter pruningCatch wireDownward cane growth form spur budsUpright growing shootsCatch wireCordonsSpursDiagram 6B.Low-Head BilateralCordon SystemBefore pruningAfter pruning

horizontal trellis is used for theGeneva double curtain (GDC) system (Diagram 7). This system usesthree wires. One wire, attached tothe posts about 3 feet aboveground, is used for trunk support.Two parallel, horizontal wires attached to the ends of 4-foot longcross arms secured to posts at 6feet aboveground hold the cordonsor canes.Descriptions of posts, anchorsand wire needed for trellises reflectthe needs in commercial vineyards. Limited plantings usingonly a few vines per row may notneed such a heavily constructedtrellis.Posts should be long-lasting.Wood posts should be treated forin-ground use and should last up to20 years.Line posts should be at least 8feet long. The posts should be setat least 2 feet in the ground andextend aboveground 6 feet ormore. Line posts should have a topdiameter of 3 inches or more. Theyshould not be spaced more than 24feet apart. Depending on vinespacing, two or three vines may bebetween line posts. Line posts areused to maintain the correct wireheight in rows (Diagram 8).End posts are used to maintainwire height. All wire tighteningand tensioning is done from theend posts, so they need to bestrong. End posts should be at least10 feet long to allow them to be set3 to 4 feet in the ground and stillhave at least 6 feet of postaboveground (Diagram 8). Theseposts should have a minimum topdiameter of 4 inches. Larger end4 ft5 - 6 ft2 - 3 ft16 - 20 ftDiagram 7.Geneva Double-Curtain(GDC) TrellisDiagram 8.2 - WireVerticalTrellis3 ft3 ft3 ftDiagram 9.End Post andBrace for aSingle-WireTrellisPosts 16 - 24 ft apart2 ft5 - 6 ft4503 - 4 ft3003 - 4 ft

posts are suggested for Genevadouble curtain trellises. The stability of an end post can be increasedby setting or driving it so theaboveground part of the post isangled away from the vineyardat about 30 degrees from the vertical and braced or anchored(Diagram 9 ).Many types of braces or anchors can be used. A screw-in anchor 4 to 6 inches in diameterworks well. The anchor should beset 4 feet away from the base ofthe post and screwed in at a 45degree angle toward the end postand aligned with the row. The anchor should go in the ground atleast 4 feet.The wire suggested to supportthe weight of the canes or cordons,foliage and the crop is a number11, crimped, high-tensile (210,000p.s.i.), steel wire with a class IIIgalvanizing. Lower wires used fortrunk support or for securing theends of canes on some systems canbe of a lower tensile strength.Uncrimped number 11 or 12 galvanized fence wire works well.Wire may be secured to lineposts by stapling it with a 1 to 11/4 inch fence staple in the top or inthe side 2 to 5 inches below the topor by drilling a hole in the line post2 to 3 inches below the top andthreading the wire through it. Ifusing staples, be sure to not drivethem in tight, as this could weakenthe wire and also prevent tightening and retensioning the wire.Taut wires are necessary tominimize sagging of cordons orcanes, to reduce development ofcrooked trunks and to promotegood light penetration throughoutthe canopy of the vines. CornellUniversity recommends tensioningthe wire to 250 to 300 pounds.Many different types of training systems are used in grapes.The following listing outlines conditions that might favor the use ofa particular training system (Diagram 10):1. 4-Cane Kniffin — use on lowvigor varieties so canes on theupper wire do not shade those onthe lower wire.2. Umbrella Kniffin — suggestedfor high-vigor varieties such asConcord, Niagara and Fredonia.3. Hudson River Umbrella — useon vines having medium to highvigor.4. Bilateral Cordon — use on vinesof low to medium vigor.5. Geneva Double Curtain — suggested for vines high in vigor.Regardless of the trellis systemor training system being used,pruning and training of newly setvines is the same. New vinesshould be cut back to a singleshoot. That shoot should be cutback to two buds prior to budbreak to maximize shoot growththe first growing season. If the trellis has been constructed at the timeof planting, loosely tie a stringfrom the vine to the lower trelliswire and secure the new shoot tothe string. This is important in developing a straight trunk, whichpromotes a stronger, more productive vine. If the trellis has not beenconstructed by planting time, set astake beside the vine and looselysecure the trunk to it as it grows(Diagram 11). If more than oneshoot develops, pinch the tip out ofall of them except the one selectedto be the trunk. Trunk developmentis the prime consideration in training a new vine. For some types ofgrapes that tend to be more susceptible to cold injury, having two ormore trunks may be advisable. Onvines grown from rooted cuttings,the second trunk should originateat or below the ground line. Forgrafted vines, the second trunkshould originate above the graftunion. Ideally, the trunks should beof different ages to lessen thechance of cold injury damaging allthe trunks. Trunks should be renewed about every 15 years. Incases of cold injury, mechanicaldamage or other problems, trunksmay need to be renewed sooner.4-cane Kniffin systemThe 4-cane Kniffin system(Diagram 12) uses fruiting caneson both the upper and lower wires.Wires should be 3 feet and 6 feetaboveground to facilitate good air,light and spray penetrationthroughout the canopy. With vigorous vines, the lower tier of canescan be heavily shaded, resulting inlow production and poor-qualityfruit. Where this problem arises, itis possible to convert to the umbrella kniffin system. If possible,orient rows on the 4-cane kniffinsystem north and south for the bestperformance.

4-Cane Kniffin SystemBilateral Cordon SystemUmbrella Kniffin SystemHudson River Umbrella SystemDiagram 10.Common Training Systems for GrapesGeneva Double Curtain(GDC) SystemDiagram 11. Pruning and Training First YearLoosely tie 1new shoot to avertical stakePrune to 1 shootwith 2 buds

CaneRenewal spur3 ft8 - 10 ft3 ft3 ftTrunk2 ft8 - 10 ftDiagram 12. 4-Cane Kniffin SystemDiagram 13.Vertical Trellis Systems FirstDormant PruningDuring the first dormant pruning (one year after planting), headthe trunk about 4 inches above theupper trellis wire (Diagram 13).Lateral branching will result fromthe heading cut and canes that willfruit the following year can be selected. In some cases, sufficienttrunk growth may occur to allowheading the trunk above the wireduring the growing season. Eliminate all flower clusters, as the primary goal at this stage is to develop the vine and fruiting will reduce growth. During the next dormant pruning, canes can be trainedto the upper and lower trellis wireson each side of the trunk.Pruning mature vines (Diagram14) involves the following steps:1. Remove at the trunk all canesthat bore fruit the previous year(old wood).2. Select canes that grew theprevious year (new wood) oneach side of the trunk near boththe upper and lower wires andtrain them to the wires. Thesecanes will bear the next fruitcrop.3. Select four more canes from theprevious year. Keep one on eachside of the trunk for both theupper and lower wires. Prunethese canes back to two buds.They are called “renewal spurs.”From them, shoots will grow.Some of these shoots will beselected using the above criteriafor fruit production in two years.4. Shorten the four canes retainedfor fruit production to eight budseach for weaker varieties and 10to 12 buds each for strongergrowing varieties. Thistechnique is an approximationof the balanced pruning conceptsuggested for commercialBefore pruningAfter pruningFruiting cane, 8-12 budsRenewal spurOld woodTrunkNew woodDiagram 14. 4-Cane Kniffin System, Mature Vine

Shootsvineyards. If desired, thebalanced pruning concept,described later in thispublication, may be used formore precisely determining theoptimum bud number.RenewalspurThe umbrella Kniffin system(Diagram 15) is a modification ofthe 4-cane Kniffin system. It is ahead-training system suggested forvigorous varieties where more ofthe fruiting area is exposed tosunlight than would be the case inthe 4-cane Kniffin system.At planting, vines are handledas previously discussed. The trunkshould be headed about 6 to 12inches below the top wire. Two tosix canes having eight to 15 budseach arising from the head (orheads) of each vine are selected.Each cane is bent sharply over thetop wire and is extended down tothe lower wire, where it is tied.Approximately the same numberof renewal spurs as canes are left.The renewal spurs should be leftnear the head of the vines. Arms atthe head of a mature umbrellaKniffin are usually kept at least 1foot or more in length.The Hudson River umbrellasystem (Diagram 16) is amodification of the UmbrellaKniffin system where the armsextend along the top wire halfwayto the next vine. These arms, nowcalled cordons, will live and bearfruiting spurs for several years.Spurs arise along cordons andArmTie shoots to the lower wireTrunkDiagram 15. Umbrella KniffinCordonsTie shoots to the lower wireDiagram 16. Hudson River Umbrellashoots that grow from buds on thespurs are directed verticallydownward and tied to the lowerwire. At pruning, head shoots (nowcalled canes) back to three to fourbud spurs. Remove some spursdirectly at the cordon to stimulatedevelopment of new growthdirectly off the cordons.Some types of grapes have adownward growth habit, whileother types grow up. The cordonsuppo

ropean varieties and certain wild species found in America. Fruit from the “hybrids” is used prima-rily for wine. Varieties include Seyval, Vidal, Foch, DeChaunac, Chambourcin and Chancellor. Many of the hybrid varieties will perform as well as several of the American bunch varieties. Muscadine grapes