For the first time in 40 years, deer (I think) have regularly eaten the tops of my asparagas down to about 12 inches. I was able to harvest stalks if I cut them at about 8 to 10 inches. Now the plants have sent out wispy fronds, but also many stalks have died, and the patch looks dismal. Should I fertilize now? In the spring? I hesitate to add more plants to the bed because digging down deep may destroy the established roots that are there. Have you heard of other instances of deer eating asparagas? The tops were bitten off and left on the ground, so they might not have eaten much, yet they returned again and again to do the same scenario.
Deer will eat anything, even the wreath off your front door. If they cropped off the asparagus only recently and the bed is 40 years old, the asparagus will regrow in the spring from the extensive root system. Cut off anything that is dead. Apply fertilizer in late winter or early spring. https://extension.umd.edu/growit/vegetable-profiles-asparagus vw