Japanese Minowase, Chinese Daikon, Iwai Daikon, Daikon Miyashige are a few of the many to be found in seed catalogs.
Hailstone White Globe Radish is another old heirloom from the early 1900s. It is roughly the same size and shape as standard radishes, but not quite as pungent.
White Globe is similar to Hailstone but larger. The roots are sweet and crunchy and it resists cracking.
Sakurajima Mamoth is a giant white Radish - lauded as the largest Radish in the World. They have been recorded as larges as 100 lbs. but the average specimen is only about the size of a turnip - that's still a lot of radish to bite into !
Sow outdoors 4 to 6 weeks before average last frost, soil temperature should be above 40°F.
Radishes need at least six hours of sunlight daily. They do best in loose well drained and fertile soil. As with all root crops you should avoid excess organic materials and manure or fertilizers high in nitrogen. Excess nitrogen will encourage lush foliage at the expense of the roots.
Don't plant radishes in a bed that hosted a cole crop in the last three years. If you incorporate plenty of wood ashes in the soil the root maggots shouldn't be an issue.
Soil ph 6.0 - 7.0 Acceptable. 5.8 to 6.8. is optimal.