Walter:

Is there some particular reason why you want to fertilize your grapevines? Grapes usually need little to no fertilizer to grow and produce well. I am sure that the 20-20-20 would be fine for your drip system, but I would not use it routinely on grapevines. You could get a lot of bushy, succulent growth, and not many grapes.

Don Yellman, Great Falls, VA

don thank you for the respond the vines are new an weare not geting any rain to melt the fertilizer thay why i was ask about the 20-20-20-

Walter,
When I first started my grapes ( 10 years ago ) a friend of mine from Texas A&M told me in the first growing season to use a balanced liquid fertilizer every 14 to 30 days.
This allowed for strong root growth and healthy cane estabilishment. And discouraged fruit set to allow the vine to become established. After the first season I have applied a LITTLE granual in early spring.
I guess you have to ask yourself what is the priority for your grapes this season, trying for fruit set... or establish the vine for next season. In Houston, in late May we would have little hope of setting bunches at this late date. It may not be the case for your area.

It worked for myself, but every garden and gardener is different.
Hope it helps
Wade Warner Houston, TX