if you dont take all the bee's honey it will store enough to winter its self and you shouldn't have to feed unless a hive is short on stores, not being from Michigan and way away from it, the main thing to look for in any flow is if they are working a plant that you can see them doing it, some uncapped nectar in the cells, most of the time uncapped nectar is a sign of a flow large or small, as long as they are working the goldenrod I wouldn't worry, after the goldenrod dies off check each hive and see what stores they have and if a hive is short on stores then you can feed to help them out.... just my opinion!!!