asparagus problems

We have problems with our asparagus. Our asparagus is tall and ferny it has been planted for 4 years and never changed looks.

This year we planted more and they are doing the same thing. We did manage to put dirt on some and they are thick and look like asparagus.

My question is what do I do to get the ferny ones looking and growing like they should be??? Thanks for your help. I'm desperate!