Question
sowed turnip seeds straight into grown in early April. came back from holiday last week and the tops have started flowering and the turnip hasn't grown. whats wrong

Answer
Dear Val,
Some seeds only produce the greens.  I don't know if that is what you purchased or not.  Usually the packets of seeds are marked, but I have seen the occasional misprint.  Last year we planted "turnip greens" and this year went to great lengths to be sure to find just old fashioned turnips.  
We had that happen with one package of radishes, this year, could just be a bad batch of seeds.
It's not to late to replant, but don't use the same seeds.  
Kind Regards,
Kindred
www.eingedi.us