Blueball Grapes In The South

I have an bluebell grape vine growing. I really can't remeber how old it is, not very, but its about 3' tall. Now the leaves are a real dark green and some are turning dark purple like magnesium difficeincy it think. I want to give its some light feedings with fox farms. Also I will be transplanting it does anybody when the best time to do either one of these things?

Thanks