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Why is it necessary to prune grapevines?

Grapevines produce fruit clusters on the previous season’s growth.  Before pruning, a grapevine may have 200 to 300 buds capable of producing fruit.  If the vine is not pruned, the number of grape clusters would be excessive and the grapevine would be unable to ripen the large crop or produce ....

How can I prevent “bees” from damaging my grape crop?

The bee-like insects are probably yellowjackets.  Yellowjackets are social wasps that build paper nests either in the ground, a log or landscape timber, or building wall or attic.  The workers from the colony travel up to a few hundred yards from the nest while looking for food.  In early summer, ....

What is a good planting site for grapevines?

Grapevines can be grown on a wide range of soil types.  Best growth and yields are obtained in well-drained soils.  Avoid soils that are persistently wet during the growing season.  Highly fertile soils are not essential.  Grapevines tolerate a wide soil pH range.  A slightly acidic soil with a pH ....

How do I control Japanese beetles on my grapevines?

In home gardens, small numbers of Japanese beetles can be controlled by handpicking.  The best time to physically remove Japanese beetles is early morning when the beetles are sluggish.  Collect or shake beetles into a bucket of soapy water and discard.  If handpicking is not feasible, applications of an insecticide, such ....

How can I propagate a grapevine?

While grapevines can be propagated by several methods, they are most commonly propagated by hardwood cuttings.  Hardwood cuttings are made from the dormant canes of the preceding year’s growth. Cutting material should be collected in late winter.  Home gardeners pruning their grapevines in late February or March can make cuttings from ....

How can I keep birds from eating my grapes?

The best way to prevent birds from eating the grape crop is to place netting over the grapevines.  Netting can be purchased at garden centers or through mail-order companies.  When placing netting over the grapevines, make sure the netting is secured to the ground to prevent birds from entering from ....

The berries in my grape clusters are not ripening evenly. Why?

Several factors could be responsible for the uneven ripening of the berries within a cluster.  Possible causes are over-cropping (too many grape clusters on the vine), a potassium deficiency, moisture stress, or 2,4-D damage.  Over-cropping is the most common cause for home gardeners.  An average grapevine may have 200 to 300 ....

I have wort-like growths on the undersides of my grape leaves. What is it and does it need to be controlled?

The wort-like growths on the grape leaves were probably caused by the grape phylloxera.  The grape phylloxera is a small, aphid-like insect.  The grape phylloxera has a complex life cycle that affects the leaves and roots of the grapevine.  The foliar form survives the winter as eggs under the bark of ....

When can I plant grapevines in my garden?

The best time to plant dormant, bare-root grapevines in Iowa is early spring (late March and April).  If planting must be delayed for several days after purchase or their arrival in the mail, moisten the packing material around their roots, place the plants in a plastic bag, and store them ....

When should grapes be harvested?

Grapes should not be harvested until fully ripe.  The best indicators of ripeness are color, size, and flavor.  Depending on the variety, the berry color changes from green to blue, red, or white as the grapes approach maturity.  At the fully ripe stage, the natural bloom on the berries becomes more ....

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