J52 is right about nitrogen .
I think that she knows her onions !
If you can - get Dr Hessayon's book on growing vegetables , produced in the late fifties - his series is tried and tested . They seem to have gone out of fashion .
I bought a set for 50p in a charity shop .
I can't remember what he recommends for radishes .
Low nitrogenous feeds include Vitax Q 4 and Tomatorite .
I've had radishes that were so wooden that you could drill a hole in them and wear them as a bead necklace .
The reason - I put a nice thick layer of well rotted horse manure at the beginning of the season and dug it in .
Up came lush leaves in profusion and my wooden beads .
I gave two sisters - a selection of my prize winning iris .
Whatever you do , I said , don't use manure as a fertiliser.
They did .
The whole lot after producing nice leaves rotted into a stinking mass .