Bob , I inherited an old asparagus patch and haven't really done much with it. I've lived here 15 yrs. I don't fertilize but maybe I should. I read that adding sand to the bed is beneficial. Last fall I dug up around the plants to give them a chance to spread . They did and I was rewarded with some nice thick stalks where I always had the skimpy ones. The soil must have been too compact after all these years. I hope someone else can give their 2-cents on when to transplant them. I'd like to move the entire bed to another spot in the garden.

Hi Bob, do you have any pests undermining your beds ? I had much the same problems---- it seemed the more I mulched, the more I summoned the moles/voles to "come and get it". Afer 20 yrs(some good harvests),I finally turned over the beds. I might establish a small bed or two with a perimeter of deeply embedded mesh. I sure do
miss those 1st pickings of the season, whether the stalks were thick or thin. Did you notice any tunneling when you removed the mulch this spring?
Joe

No Joe, didn't notice any tunneling.
But, do have alot of shale in this area, probably only good soft topsoil down to about 4-8 inches.
Maybe this is the problem?

asp.plants are like miniature oak trees,not shallow rooted. so that could be a good part of your problem.
you should keep building your soil,if you do mulch over winter you should try to leave it in place instead of removing it. you should also add a layer of good topsoil (a few inches) each season,not too much,to increase the depth of
your beds. also,add some bone meal before covering w/ mulch or additional topsoil. this will def.help plant vigor. good luck, jp.