Planting out asparagus crowns

The crowns that I bought already have fairly long green shoots on them (not sure if that's how they are supposed to be), and I'm wondering if it would be a bad thing to plant them so that the shoots are already above the ground, or should they be just under the surface?

Thanks Tony. Yes, I did know that. Also picked up another good tip from another member on here - to plant the crowns in sand to stop them rotting when it's wet.

Right, I'm off to finish digging my trench, and hopefully get the crowns in before the day is out!