Late flow of Mustard and radish

[Norfolktoad]

I have 3 hives a 2014 nuc which is covering 10 frames. I have taken off 1 super and got 18lb of honey. It crystalised in the extractor, but I was able to get it jarred by heating up the room and it eventually flowed through the filter and I jarred it up immediately. I believe this honey is a mixture of mustard/radish (50 ac field 100 yds away) and ivy. This hive is still working well and drew out and filled another super in a week. Should I leave this for the bees although it will crystalise? The other 2 hives I bought a couple of weeks ago, these are not working so well, I suspect there was not a flow at their old home. I am feeding these with a thick syrup.

Am I doing right with these hives.

Any advise is appreciated.

Mike