when would be the best time to place honey supers on hives in utah around salt lake city when to super ??
Due to the nature of the question I will assume you are asking about a new hive, rather than an established colony.
It is always best to add new hive bodies as the previous body is 70% full. Just like the brood chamber, as 7 out of 10 frames of your first body are drawn, add the second. Continue with the same procedure until the fall.
Phoenix is right if you're asking when to add brood supers. But you asked honey supers. So the answer must be You're Late.
I don't know when but it's before now. That is assuming you have the first two brood boxes 70% drawn out by now.
Get em on and watch the honey come in. That's the fun part.