How Much Fertilizer for Grape Vines?

Soil Requirements

• Grapes grow in many different soil types but don't like extremes. Any type of soil that is too rich, wet or dry can cause problems for grape vines and diminish their fruit production. Grapes are typically grown on hillsides with poor soil of a rocky or gravel-like consistency. The rocky soil is excellent at absorbing heat from the sun and slowly releasing it, warming the grape vines. Another benefit of rocky soil is that it is fast draining. To a grape, that means everything because under all circumstances they don't like to be waterlogged. When it comes to soil pH, different varieties of grape vines prefer different levels. Most vines thrive in soil with a pH between 5 and 6. Prior to planting grape vines, soil should be mixed and worked down to a depth of about 2 1/2 feet.

Why Fertilize Grape Vines

• Grape vines are pretty easygoing when it comes to feeding. They are not heavy feeders by nature and therefore don't need to have diets that are adjusted constantly by their growers. Grape vines need to balance vegetative growth with fruit production and too much of any one nutrient can throw this system out of whack. The results can be a vine that grows rapidly but produces puny fruit. Some growers don't feed their vines at all, but vines that are fed produce significantly more fruit.

Types and Amounts of Fertilizer to Use

• Compost is the most effective and widely used fertilizer for grape vines. Well-rotted compost usually contains a good balance of essential nutrients and should be used when the grower isn't looking to boost levels of any one particular mineral or nutrient. Compost should be applied at the rate of 15 to 20 lb. per 100 square feet and is often spread in a single line down the row of planted grape vines. A standard 10-10-10 fertilizer can also be used, especially in the grape vine's first three years following planting. Sprinkle about 1/4 lb. of 10-10-10 in a circle about 1 1/2 feet away from the main stem after planting. In the second year, increase rate to 1 lb. and in the third year increase again to 1.5 lb.

When to Fertilize Grape Vines

• Most growers fertilize their vines in the fall following the grape harvest. Grape vines can also be fertilized in the spring prior to bud break. Applications of fertilizer during the growing season are not recommended because it will cause the grape vines to grow vigorously. That in turn can produce inferior fruit and set the vines up for failure during the harsh winter months ahead.