>sweetness is determined by how much water you give them and how long you leave them on the bush with wine grapes, sweetness (and other flavor qualities) depen

>sweetness is determined by how much water you give them and how long you leave them on the bush with wine grapes, sweetness (and other flavor qualities) depend on the sunlight times ratio of surface area of leaves to number of "berries". If the weather is great, you can grow more great grapes, but if the weather is poor you prune off half the fruit when it is still small and green (it's called the green harvest), and the remaining grapes come out higher quality, concentrating the sugar from more leaves. You might try it with a blueberry bush to see if those fruits taste better.