I didn't realise that one of the varieties of radish I bought was a winter radish. (I'm not sure even now how large the bulb is supposed to grow, it's called "Red Flesh" and is a Japanese variety.) So I sowed alongside the normal stuff in April, thinned it to 1 to 2 inches, like the normal stuff. It has grown tall, with a thick central stem, is flowering, and is not producing any root bulb volume. Normal radish treated the same way is giving me a crop.

What should I do with this winter radish? Wait? Thin it out to a wider spacing and wait? Cut off the central stem? Pull it all out and throw it away?