The roots do die back after the foliage does, but make sure you mark the spot well. I've been so sure I was digging in the right spot before and unable to find the bulbs, LOL. Bev is right, a bigger spade or fork is good for digging them. They tend to work themselves deeper into the soil after a few years. The bulbs are pretty tough, so aside from slicing through them, you don't have to be too concerned with damaging them.
