Always adjust rates of fertilizer application according to annual shoot growth. Apply fertilizer in late winter or early spring before growth begins. Fertilizer should be broadcast on the soil surface around the drip line of the tree. Avoid getting fertilizer within 6 inches of the trunk as it could burn the tree. Note that most commercial orchards use leaf or stem tissue analysis to determine fertilizing needs.
Most folks inadequately prune their grapes and end up with numerous small clusters of small grapes.
In general, prune grapevines back to the first two buds produced by last year's growth. Train vines to fit the trellis or arbor by selective pruning the vines regardless of when the growth was produced. The most important thing to remember is that you are not likely to kill ANY plant by improper pruning. Fertilizing grapes is different from most other tree fruits. Repeat every 6 weeks until early July.