I'd cover everything I possibly could if it were me 
we have had frosts in June before, even down here 
Too big to cover but I will put a large fan out that my husband uses in the gym. I believe that the French use helicopters to create air turbulence over there most expensive vines if frost is feared. I also read an article about how a fan is one of the best ways to prevent frost forming.
They do something like that in California to help prevent frost where they grow oranges. Frost forms when the ground cools to the freezing point, and mixing the air transfers heat from the warmer air aloft to the ground, keeping it above freezing. If you live in a valley, you are more susceptible to frost on clear cold nights, as cold air on the hills can drain into the valleys resulting in a temperature inversion from valley floor to hill summit.
