ripening grapes on a vine
Updated: April 12, 2024

About grapes

  • Grapes are long-lived woody perennial vines with a very deep root system. Established grapevines are difficult to dig up and move.
  • Fruits form on second-year wood, although older latent buds (dormant until stimulated into growth) sometimes flower and fruit on older wood.
  • New shoots emerge from arms (short branches connected to the trunk) in spring. Shoots don’t end with terminal buds; instead, they grow all season. First-year growth is called a shoot; the second-year growth is called a cane.
  • Compound buds with 4 growing points form during the summer. If a late spring freeze kills the primary growing point, other growing points will take its place but will produce a smaller crop.
  • Lateral (side) shoots grow from overwintered buds and produce leaves and 1-2 flower clusters (panicles) each.
  • Botanically, the fruits is a true berry. Grapes are self-fruitful– pollen from one plant of one cultivar is effective for fertilization and fruit growth. Bee activity is required for the best fruit production.
  • Black rot is a widespread, significant fungal disease that often reduces yields.

Cultivated grape species

Fox grape (Vitis labrusca) - Locally native and wild in much of the eastern U.S. The source of all seeded and seedless table grape cultivars (used for fresh eating). Most gardeners prefer seedless grapes. American table grapes are naturally resistant to Phylloxera, an aphid-like insect that, in large numbers, severely damages and kills the roots of susceptible grapevines.

Muscadine grape (Vitis rotundifolia) - Not reliably winter-hardy in Maryland, although that may change as winters become warmer due to climate change. Native to the southeastern U.S.

European wine grape (Vitis vinifera) - They can be grown successfully by gardeners, but require more specialized knowledge of site requirements, pruning, and pest management.

  • Recommended Wine Grape Cultivars for Regions of Maryland by the Maryland Grape Growers Association
  • V. vinifera cultivars are generally less cold-hardy and more susceptible to black rot and other diseases than V. labrusca cultivars. 
  • Wine grapes must be very ripe to make good wines. 
  • Canopy management and good exposure of clusters to light are more critical for wine grapes. 
Recommended Table Grape Cultivars 
Cultivar Comments
Canadice Seedless. Early, small-medium red grape with superb flavor. Keeps on the vine. Reliable and productive.
Himrod Seedless. Golden yellow fruit with a fine flavor that keeps well. Very cold-hardy; moderate disease resistance.
Jupiter Seedless. Large, crisp blue fruit. Non-slipskin. Excellent flavor.
Mars Seedless. Very hardy, productive, and dependable. Large blue fruit.
Neptune Seedless. Very large, yellow-green fruit; some disease resistance.
Reliance Seedless. Dependable variety. Very hardy vines. Large, high-quality red fruit will store for 3 months.
Steuben Seeded. Very large, blue, spicy fruit. Hardy, with some disease resistance.
Sunbelt Seeded. Similar to, but more heat-tolerant than Concord.
Vanessa Seedless. Brick-red, medium-sized grapes. Firm texture and fruity flavor.

Notes: American bunch grapes (V. labrusca) have slipskins that separate easily from the flesh (undesirable for table grapes). Mars and Sunbelt have V. labrusca parentage only. The other cultivars are hybrids of V. labrusca and V. vinifera.


  • Plant vines in early spring in a full sun location. Sites with early morning sun will allow the foliage to dry more quickly, reducing disease problems. Soil must drain well and should have an acidity level (pH) in the range of 5.5 to 6.5.
  • Good air circulation will help prevent disease problems. Overcrowding frequently results in poor air circulation, weak plants, and low yields. Select a planting site with shelter from strong, prevailing winds, and avoid frost pockets (low areas where cold air settles overnight).
  • Space plants about 8 feet apart.

Training and pruning

Grapevines must be pruned every year to remain fruitful. Any shriveled fruit clusters remaining on the vines or trellises, plus all pruning waste, must be removed from the vineyard during the dormant seasonand destroyed.

Grape pruning terms

  • Cane: a mature woody shoot (1 year old or older)
  • Cordon: a horizontal extension of the trunk, trained along a trellis wire
  • Lateral: side branch, either a shoot or cane
  • Shoot: current season’s growth
  • Spur: a cane pruned back to 1 to 3 buds
  • Trunk: vertical structure of the vine, from the root system to fruit-bearing wood

Grape pruning tips 

  • Prune in March so you can determine the amount of winter damage. Leave more buds after particularly harsh winters.
  • Typically, 90 percent of the previous year’s growth is removed during dormant pruning.
  • Ignore the heavy sap flow from fresh pruning cuts made in spring. This will not weaken or damage your canes.The sap may cause contact dermatitis (skin irritation) in some individuals. Wear gloves when pruning.
  • Failure to prune hard leads to fewer flower buds and small, poor-quality fruit. Insufficient pruning can also trigger a biennial bearing pattern, where plants skip a year between harvests. Don’t allow more than 2 flower clusters per shoot to develop.

Training grapes

You can train your grapes to grow on arbors, fences, and trellises. If trying to cover an ornamental structure, prune for a longer trunk and leave more fruiting canes each year.

For best fruit production, the “two-arm” system (illustration below) is the simplest to follow. This system supports the vine with a heavy (# 9 gauge) wire stretched between posts 5 feet (60 inches) above the ground. Use sturdy posts 7 feet long and 3 to 4 inches in diameter. Set the posts 2 feet into the ground and space them 20 feet apart. Nail or staple the support wire to the top of the posts.

an illustration of how to train grapes in a t-shape along a wire trellis
Two-arm pruning system. Reprinted with permission: SC Nursery

Pruning young grapevines

Second year

In early spring, select the best of the two original shoots to become the permanent trunk. Prune off the other one. Tie the young vine to a stake. As the vine grows, tie it to the wire. Cut it back to a bud just above where you tie it. This promotes straight trunk growth in the vine. Leave 4 to 6 buds near the top of the vine and remove the remainder. Remove any flower clusters from the developing lateral shoots.

Third year

In early spring, select the two strongest lateral shoots, one on each side of the trunk. Cut them back to 5 to 7 buds and tie them to the wire, extending in opposite directions. Select two other canes, one on either side of the trunk, and cut back to 2 buds. These are called renewal spurs.

Pruning mature grapevines

  • Grapes produce fruit clusters on canes that are two years old. These canes are non-productive after they fruit and should be pruned off after harvest.
  • The four shoots that grow from the two renewal spurs on either side of the trunk are also pruned.
  • The strongest lateral cane on either side is pruned to 20 to 30 buds. These two laterals give you a total of 40 to 60 buds. The number of buds that you retain for fruiting is determined by the vigor of the vine.
  • When a vine is weak, leave no more than 40 buds. A vigorous vine can support 60 or more buds.
  • The other two shoots are pruned to 2 to 3 buds and they become the renewal spurs.
  • Each year, you are removing the fruiting wood from the previous year and selecting new shoots (renewal spurs) to become next year’s fruiting wood.


(Video) Grape shoot thinning | University of Maryland Extension 

(Video) Mature Grape Vine Pruning Demonstration | University of Kentucky

(Video) Spring Vineyard Pruning | University of Maryland Extension 

Dormant Cane and Spur Pruning in Bunch Grape Vineyards | Penn State University


  • The first crop is usually harvested 3 years after planting.
  • For best quality, bunch grapes should be fully ripe when harvested. Grapes will not improve in sugar content or flavor after picking.
  • Once fully colored, grapes can be left on the vine for up to 1 week before harvesting. As harvest nears, protect the fruit from birds to allow it time to sweeten. Place mesh bags or insect netting over fruit bunches to exclude birds from the fruit.
  • Cut the bunches off with a knife or hand pruners to avoid bruising the fruit and damaging the vine.
  • Regularly harvesting ripening fruit clusters will reduce nuisance pests such as fruit flies, sap beetles, and yellowjacket wasps.

Plant and pest problems

Grapevines are vulnerable to several diseases and insect pests. They are also very sensitive to spray drift from phenoxy (growth regulator) herbicide ingredients like 2,4-D.

rotting wrinkled grapes due to black rot disease
Black rot on grapes. Brian Olson, Oklahoma State University,

Black rot 

Black rot (Guignardia bidwelli) is a common fungal disease of grapes in Maryland, both for commercial and backyard growers.


  • Leaves develop brown, circular spots, which develop many tiny, black, pimple-like structures in their centers.
  • Most berries are reduced black, shriveled, raisin-like mummies.

Life cycle 

  • The pathogen overwinters in mummified berries from the previous season’s crop. Spores are released during wet periods, when new shoots first emerge before blooming.
  • Young leaves are infected first. The leaf lesions produce thousands of spores that can infect the fruit.
  • In general, the leaves are susceptible to infection for about 1 week until they are fully expanded. However, the fruit is susceptible until just before ripening, when berry color is developing. As the skin thickens with ripening, the fruit is much less vulnerable.


  • There are no resistant cultivars.
  • Minimize the risk of infection and severe disease by removing infected fruit, cleaning up mummies, and pruning off leaves that surround fruit clusters.
  • Preventative fungicide sprays are a necessity to ensure edible fruit. Make the first application before flowering, when shoots start to grow in early spring. If using organic sprays, sulfur may cause phytotoxicity (foliage chemical burn) on certain varieties, and it is not as effective as Bordeaux (an effective organic fungicide consisting of copper sulfate and quicklime).
shiny brown insect on grape leaves - Japanese beetle
Japanese beetle (Popillia japonica) and feeding damage on grapes. Photo: Ansel Oommen,

Japanese beetle adults 

Japanese beetles tend to congregate and feed on grape shoot-tip leaves in large numbers. The adult beetles are present for only a short time in early July. Although their damage may look drastic, it seldom is severe enough to damage the crop.

Knock Japanese beetles into a bucket of soapy water; they tend to drop off a plant when disturbed. Avoid using Japanese beetle traps because they tend to attract large numbers of beetles, which can lead to additional plant damage before they find and enter the trap.

insect chewing damage on grape leaves
Japanese beetles and their chewing damage on grape leaves. Photo: David L. Clement, University of Maryland Extension
bumps on the back of a grape leaf - insect damage
Leaf galls caused by grape Phylloxera (Daktulosphaira vitifoliae), an aphid-like sucking insect. Photo: Whitney Cranshaw, Colorado State University,


Phylloxera is an aphid-like sucking insect with both root- and leaf-feeding life stages. The root-feeding stage causes the most plant damage. It can be prevented by using only the recommended resistant rootstocks or planting American-type grapes.

The leaf-feeding stage induces the formation of many tiny galls (swollen nodules) on the shoot tips and leaves, which can cause them to become stunted and deformed. The damage is quite prominent but causes little overall stress to the plant unless populations are very large. 


Author: Jon Traunfeld, Extension Specialist. Reviewed by Miri Talabac, Lead Horticulture Consultant, and Christa Carignan, Digital Horticulture Education Coordinator. 4/2024

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