How many acres would not have as much to do with it as what else is in the area that the bees would prefer over the buck wheat.
Organic Gardening says that one acre will take care of 100 colonies. I don't know!
If you plant the buck wheat so it will come into bloom when there is nothing else to amount to much,
Which would be July and August in central Ga., unless you have some Kudzu close by.
Buck wheat, once it starts, will bloom till frost cuts it down. Makes a good cover crop to till in to the ground in the fall. Plus the bonus of getting honey from it.
Remember, what you can plant should be planted so it will bloom during a dearth. Then you have a better chance of getting that kind of honey more on the pure side.
JMO and I'm sticking to it. :)doak