If your asparagus has been established for more than a couple of years, I think it will be pretty hard to kill completely... I don't think you want to mistreat it though. I'll tell you what we do, it's based on old timer advice and not so much old time experience. If anybody else comes along and says I'm crazy, they will be the new expert. This is just my experience and unscientific reasons.
I was always told to leave the ferns on through the winter to catch snow for moisture. Thinking about that now, the last thing we really need in NW Ohio in early spring, is more moisture. I was also taught to burn the ferns off in early spring, this will blacken the dirt and it will warm up faster, so you'll get spears earlier.
Where I grew up, we had
The North Farm, on the north farm, was
The Old House. It was an abandoned homestead, a half mile walk from home, or about a mile and a half if we drove (the point is we usually walked). Anyhoo, there was a big old asparagus patch back there that had been around for ever. We had a small patch at home, but if we needed alot for a big meal, we'd go to the old house. Sometimes, we didn't get the old ferns burned off and there was always new asparagus coming up, the same time we were getting it at home, in the patch that was "properly" cared for.
Here's what I think; the ferns go to seed in the fall, but they hang on the plant until spring. Jostling the plant around, cutting it down to burn, knocks those seeds loose, so you'll get new ferns. I'm guessing you live in town, so burning is probably out of the question. I'd just cut them off in the spring and give them a good shake, before disposing of them. This should give you a few new ferns every year, to make your patch thicker.
The only real advise I will give, is
never pick a stalk smaller than a pencil diameter. The first year from seed, you'll get a fern. The second year, you'll get a skinny stalk. The third year, if you've had good conditions, the stalk will be big enough to pick. If you do nothing else, follow the pencil rule and you should be good to go.
Like I said, anybody that comes along and says I'm crazy, can be the new Pro. This is the way I was
fetched up, and the way I will continue to do it..... YMMV
Tim