They like rich compost, feeding and plenty of water, They are not an easy crop.
Are radish hard to grow? Really?
I plonk a row of seeds in any space and the things pop up like weed. If I don't remember to harvest them they rapidly reach "big" size and join the compost heap. I always presumed they were an easy thing to grow - a speedy fast growing fill- in between other things crop.
As radish are not seen as essential in my household I really don't fuss with them - dribble the seed in and wander off - splosh of water and then.... crunch! Nice in a salad from time to time.
I have ordinary clay soil.. a newish growing space (gradually improving with compost) but.. so straight-forward.
Only problem encountered (when I grew them on the allotment) was "flea beetle" as it loved chewing countless little holes in the leaves but at home... plain sailing.