When I grow radishes, I find that some of them don't swell up to form the globe I expect; instead the root stays thin. These are planted in the same bed and at the same time as radishes that do swell. I believe I'm doing everything right: cultivating the soil before planting, thinning the seedlings, keeping them well watered (when Mother Nature doesn't do it for me) and rotating crops from year to year.
What can I do to make all of my radishes plump and juicy?