Asparagus advice needed please

I have been growing asparagus in a raised bed for 3yrs now, this is the year! i havent even had one spear. so i dont want things to go wrong now.

What advice im after is i can see the top of the crowns and some roots, i suppose after 3 yrs in a raised bed there has been some wind erosion.
So can anyone tell me whats best thing to do, cover them up? if so how deep should they be? as i forgot seems so long ago i planted them, and also whats best to cover them with? I do have a lot of well rotted leaf mould would that be any good? or just some compost would that be to rich?

There also is some spear starting to sprout up now to, if that makes any difference i dont know.

Phew seems alot of questions there but i cant let things go wrong now, i want to be eating them this year 

Any advice would be great as usual. Cheers.

Compost is good because the asparagus needs to be fed like any other crop. I add this and some rotted manure first.

I too have mine in a raised type of bed and there's only so much soil in there, so I  also get a few bags of loamy type soil from the shops and add that all around so that the roots stay covered and I try to keep the same level at the root base, or if I'm early in the season, raise it into a bit of a mound.

Waterlogging the crown is the worst enemy for asparagus so a bit of mounding is always good.

Thanks everyone for your replys.

I went  this afternoon and covered them with a mixture of my compost and 2yr old leaf mould (lovely stuff) . I only gave them an inch covering tho, maybe i should do more tomorrow?

cheers MW.

I think many pieces of traditional advice have started to look a bit too precise over the last few years because the weather itself has refused to behave very traditionally, but it also depends on how mature the plants are.

It used to be said that asparagus harvesting should stop on the longest day (21st June) but that relates to well-established plants and yours are still relatively young - I think Salmo has very recently suggested on here that stopping 3 weeks from the first cut is a sensible plan for young plants and I for one can't disagree.