An ideal size for an unusually large family , or for commercial sales.
Monticello has original asparagus beds that are over 200 years old, and are still productive.
They are dug up about every fifty years just to replenish the soil nutrients;
this demonstrates the value of a well dug and prepared original asparagus bed .
And there you have touched on the foundation to having good success growing asparagus.
What I like to do when preparing a new asparagus bed is to first dig up and completely remove the grass sod. I suppose you could kill it with an herbicide of some sort, but it's best not to spray poisons where you're going to be growing your food.
Next, dig out and set aside the soil to a minimum depth of approximately 12". Deeper is better if you have the gumption to do it. Then refill the trench with a 50/50 mix of the soil that came out, and whatever kind of good compost is readily available. Rotted cow/horse/chicken/rabbit manure is best if you can get it. Continue to refill until the trench is around 8" deep. Place the crowns leaving plenty of room in between them for future growth. They will get huge over time and they don't like to be crowded.
Cover the crowns with your soil/compost mix and then sit down and have a cold drink.