I may never go back to open-pollinated radishes. Quick, perfectly round, appropriately crimson, and not a single split radish in today's harvest. i sowed 'em thick, picked the big 'uns this week, and left the rest to bulb. I've also have some Cherriette Hybrid radishes going in a windowbox, which is a great way to grow a bunch of radishes. They love a rough and quick-draining mix, which makes sense, inasmuch as they were bred to form root structure. With cool weather, it's not too hard to keep the moisture reasonably even.