Asparagus dying off

Hi all, This is my first post here I will try to describe my issue as well as I can. I started my asparagus from seed in August and they almost all came up fine. They where doing all fine trough winter in my green house but now they all seem to die off when spring start and I am not sure if this is supposed to happen and if the crowns are still alive or not. Please let me know your ideas. Many thanks, Jortijn