Fall Radishes

Can't wait to plant these around my hugelkulturs next year.

http://www.youtube.com/watch?v=XgZo8Ztoa-I

I planted german giant radishes this year and they were incredible! very large and not pithy. They were a hit at the farmers market.

But with all my radishes, when I planted more around Aug. 1 they didnt do well. Maybe because Im in zone three.. its almost like they required the waxing sun instead of the waning sun.