I have been growing Daikon for the past two years. I always manage between 2 and 3 feet long plants (even the ones i put in containers). So growing isn't the problem.
The problem is storing. If my wife buys a daikon from the store it lasts for weeks in the vegetable drawer of the fridge. But if we pull one from the garden it has to be 'ate' withing a few days. Otherwise it gets limp and mushy. This is a real problem with these radishes, becuase at 3 feet and almost as big around as a kids ball bat we end up throwing half of each one back to compost.
Any ideas? What do the large growers do differently? Maybe withold water before I pull? I am at a loss and couldn't find anything specific online.