are developing fruit cluster. debra villalon is live. reporter: grapes need heat to grow and they re not getting it. they re coming along slowly, but that turns out to be a good thing now that they are all wet. at a sebatical wine, the birthday girl did not remember if it was okay for them to get cold. brothers steve and joe farm more than a thousand acres of grapes. i m pulling the leaves off so you can see. reporter: farmers prune to let air and sun in. and prune their vines to prevent fungus. any rain during the bloom period which is a two week period around june 1st, would not be good for us. these round things are potential berries and they cannot form. you can t restart that process? no, you ve lost that crop. last year s harvest was good quality but smaller quantity. if it warms up we can get back on schedule. but it needs to warm up. last few years have been pretty cool and we re hoping this summer is not quite as cool. reporter: getting from here