What Type of Fertilizer for Grapes?

16-16-8

• In general, grapes do not require heavy amounts of fertilizer once they are well-established. In fact, if they receive excessive fertilizer, their leaf and wood growth will be stimulated at the expense of fruit production. A moderate amount of fertilizer, from 1/4 to 1/2 cup, is likely to help the young plants prepare for producing fruit. One commonly used fertilizer known as 16-16-8 contains the following nutrients: 16-percent nitrogen, 16-percent phosphate (P2O5) and 8-percent potash (K2O). The fertilizer can be applied at a depth of 2 to 3 inches at a distance of about 10 to 12 inches away from the trunk. The time to fertilize is at the time of planting and in the plant's second year during early spring.

Compost

• Preparing the soil at the time of planting is another way to help grape plants take root and grow. Working garden compost into the soil where grapes are planted can infuse the soil with additional nitrogen and help grapes get off to a good start.

Common Fertilizer Deficiencies

• Grapes that are over watered may develop a deficiency of iron known as chlorosis. The deficiency is usually characterized by leaves that are small, pale and yellowed. The leaf veins may be dark green. When a grape plant is severely affected, the edges of its leaves can dry and become brown. Vine growth and yield will be poor. In the event of chlorosis, a two-fold approach may help. First, water less frequently. Additionally, apply either Iron Sul or Sequestrene 138, available at garden centers. Applying about 1 lb. for every 100 feet of row in the soil may help correct the deficiency.

Other Considerations

• Fertilizing late in the growing season when fruit is in its ripening period may force excessive growth and subsequently spoil the fruit. Grapes grow and produce well in soils that are moderately acidic, such as where the pH is between 5.0 and 6.0. Soil testing can help identify if acidity is optimal or if lime, a base to counter high acidity, should be added. Cool weather tends to reduce the uptake of nutrients, so having an adequate supply of nutrients available in the soil will help the young plant grow and prepare to yield fruit. When it is kept dry, fertilizer is not prone to deterioration.