No, they don't need to be right next to each other. It's really just a matter of how far the bees travel with this pollen sticking to them. So I think they can be 50 feet, 100 feet, even 200 feet away (maybe more?) as long as the bees fly around and visit them all. The important thing is that the flowers be OPEN at the same time, so that is why you get the ones that bloom around the same time.

By the way, when you're done with this ... you'll be qualified to move on to Viburnums - same issue!

Have fun! And start stocking up on blueberry recipes.

I know that I'm posting to a really dated forum, but I need to add a note about the bees that pollinate blueberries. My understanding is that blueberries are pollinated by solitary bees or bumble bees. (The tongues of honey bees are too short to reach the nectar so if they visit the plants they will get it out of a hole near the base of the flower and bypass the reproductive flower parts. Solitary bees don't fly as far as honey bees, so the plants shouldn't be as far apart as they might have been had they been honeybee pollinated. Also solitary bees are not going to gather nectar from one type of flower at a time. So I would not put the plants more than a hundred feet apart. Fifty feet apart should be OK provided the blueberry flowers are not competing with a whole bunch of other flowers for the bee's attention.