I am a newbie at asparagus also. Planting my first bed this year. I read somewhere though, that you space them 1 per square foot.

I went with the Jersey Knight Hybrid, because you can harvest a little the second year. When they go to fern they will be 2-4 feet high, so make sure that they won't shade your other plants. 12-18 inch spacing is recommended. Toss in some triple phosphate when you plant.

Here is a link that might be useful: Jersey Knight Asparagus