Generally when radishes fail to enlarge, it is because they were planted too close together and were not thinned soon enough after emergence. It is best to thin them to their mature spacing only 2 to 4 days after they pop up out of the ground. In probably 90% of the cases when radishes fail to "radish up", this is the reason. Since they mature so quickly after emerging, if they aren't thinned within that 2 to 4 day period, they just don't form round bulbs or the long icicle shape, whichever is their form, properly even if thinned, say, a week later than that.

If you did thin them that quickly after they emerged and they were at the proper mature spacing for that specific variety, the other possibilities would be low soil fertility, insufficient light or insufficient moisture.

And I assume we're talking about spring radishes, not the much larger winter radishes.

Dawn

well in regard to spacing I did make homemade seed tapes using single ply tp. If you picture a seed in each corner and one dead center this should allow enough space without thining. germination was not a problem.Beets seem to be sufferering same retarded growth. I am suspecting low light at this point as soil is good and loose and water was good. Thanks. will re try in the fall at different location. Am trying winter Rose radish any tips anyone, thanks!!

If your spacing was that far, then it has to be light, soil or moisture. How many hours of sunlight a day do they get and is it full sun during that time or more of a dappled shade/sun type situation?

Mulberryknob likely will give you tips for winter radishes when she sees this as she always grows them.

Do you like radish leaves in salad, too? What do you do with radish leaves?