Feeding Your Grape Crop
Since grapes are deep-rooted plants, they need very little additional grapes fertilizer. If your soil is poor, you may decide to amend it with grape plant fertilizer before you even plant your crop, but even then, it is recommended that you do so lightly. In the second year, all soil types can use light fertilization to replenish nutrients. Your grapes may need more fertilization as they get older becuase their nutrients are naturally being used by the plants as they grow and produce grapes year by year.
Grape Plant Fertilizer Timing
When you do need to apply grapes fertilizer, the timing is important to create the best possible yield. A phosphate fertilizer or other type of plant food should be applied in the spring, just as the buds are beginning to emerge. If you fertilize too late, it can cause overly extensive growth that can make the plants vulnerable to injury in the winter. If you must add certain nutrients, nitrogen is best to add in the spring to encourage rapid growth, and potassium can be added in late spring or early summer as the vines are beginning to produce grapes.
When applying fertilizer to your grapes, add no more than a quarter pound of a balanced fertilizer about four feet away from the vines in a circle. If in the following years, the plants seem to be a bit sad, you can apply an additional pound of fertilizer about eight feet away from the base of the vines. It is also wise to keep an eye on the amount of other nutrients in the soil feeding your grapes. Some of these nutrients provide essential functions, such as zinc that helps with pollination and hormone production.