i have grown black spanish round radishes, last summer actually, on
hugelkultur beds in cheyenne wy with very little care as i live 200 miles away, they not only survived but were one of my best yielding crops among all the uncared for plants growing down there, most bolted and formed seed early as they were never harvested but i harvested about a dozen perhaps a month ago after a week of -20F, the tops had mostly died at that point, but they were big, tasty from what ive heard (havent cooked any up myself as of yet) and in my opinion did excellent considering the amount of care they recieved
one that bolted on the hand constructed section of the
hugelkultur bed was probably two softballs large, if not three, but thats a guess from what i could see aboveground, i did not pull it as i wish for all the bolted radishes to decompose in place and form deep thick plugs of organic matter in the soil
very satisfied and even proud of the black spanish round radish and look forward to growing more next year, will hopefully see a few volunteers from all the ones that bolted as well