Okay, so technically none of them are grown for their roots, since that fleshy part we eat is actually mostly swollen stem, but that's beside the point. Back in the 1st century A.D, the historian Pliny moaned about farmers abandoning grain crops in favor of radish seeds whose oil they could sell for a handsome profit. The home gardener has many more choices available, though, from delicate elongated white icicle varieties to cylindrical bicolored French breakfast ones and others in colors ranging from black to pink to purple. If you grow your own radishes, use the thinnings from your garden in salads. The flavor of the young leaves is similar to the peppery taste of watercress.
Sprouts grown from the seeds are spicy and add lots of zest to salads and sandwiches.
I prefer the ones sold in bunches with the leaves still attached over the pre-trimmed ones because they stay fresher longer that way. Radishes picked on the same day and sliced from the leaf will hold for only a day or two, but you can keep the still-leafed ones for up to a week. To prepare radishes for serving, wash them to remove any lingering dirt, and pinch or slice off the tops and any hairy roots. If your radishes have lost a little crispness, soak them in ice water for several hours and they'll regain it. Fall radishes are grown, not surprisingly, in the fall and are larger and slower growing.