What zone are you in? The warmer the zone the shallower they're planted, up to the eyes exposed in zones where they typically don't grow. The eyes should be 2" below ground in the coldest zones. Have you thought about just mounding over the roots instead of disrupting them by moving? If they're showing signs of growing I think I'd try that! And if you're warm enough that they're showing signs of life (no damage caused by shallow planting) you'll probably not need that much soil cover.