“Single floral source”
My father kept bees along with farming in southeast Nebraska. He sold honey by mail during WWII. Sugar was rationed, but the government didn’t care about honey.
Probably early August smart weed would bloom in the fields which had produced wheat and/or oats and were not plowed yet. The fields were vast zones of pink flowers. In the hot dry summers nothing else was blooming that time of year. The bees would gather the necter and would store it. It was very dark and tasted so bad that hardly anyone would eat it. Dad left it mostly for the bees to overwinter on. However, there was/were one customer who special ordered the smart weed
Bees don’t care how the honey tastes, but people do.
You want the bees to store the fall goldenrod for the winter and harvest honey from earlier in the season but that is not always an option. You harvest what you can take and always leave enough for the colony to get through winter and summer dearths.