Foragers will work themselves literally to death in NO time on a flow. Why would you want to limit brood production before the flow? :scratch: I would be trying to grow my population. The main "flow" may be blackberries...but are you saying there are no wildflowers, trees in bloom, etc? The bees know what to do. You don't have any stores in the top corners of your brood frames? If you have things blooming, I bet the bees are just fine... Feed until blackberries if that makes you feel better, but there are more resources than just blackberries....trust me. I hope somebody from your area responds. Probably hard to listen to somebody from So FLA....and I DO admit, I do not know your flows. Pretty sure there's a lot more going on than just blackberries though.
Edited to go back to your original question....2:1 (sugar to water) is usually used later in the year to help them store without as much effort in dehydration. Whether you do 1:1, 2:1, 3:1, etc...the queen will lay what she knows the hive can support. I'd be trying to grow them as much as I could. Drones can become a burden on a hive, especially late in the season, but I don't believe workers ever are. The workers lose so much population on an every day basis that they need the reinforcements. JMO!