Some nutrients will desolve in the water and move out of the range of the roots of your future plants, so, in my view, it should be okay to cover the beds, but not necessary. Sufficient nutrients will remain in the soil around the roots of your future plants to allow them maximum growth potential. If I were you, I would leave them exposed and cover them with a layer of cospost that you can turn under in the spring before planting.

I think you should cover the beds to keep from losing nutrients and keep debris off the surface.

I cover mine with clear plastic. This has the advantage of heating up the soil when the sun shines. You can usually get painter's plastic very cheap.

Larry

Thank you both for your response. I decided to go ahead and cover them and I did indeed use painter's plastic to do it.

It has held up surprisingly well. I am glad I did it because we have had above average snow and rain and I would hate to think of all that going through the beds.

I covered my raised bed with a layer of leaf mulch (free from the county transfer center) and then covered my artichokes with whatever I could find (buckets, tubs and plastic) in the hope of getting the artichokes through the winter. Does not look promising, but time will tell.

That is so beautiful! I hope your artichokes make it through. Be sure to update!