We just moved to Maine (zone 5a) and have started some vegetable gardens. We prepared an asparagus bed with lots of rotted manure in early april, and covered it with black plastic…and never quite got around to actually getting any asparagus crowns. I’m kind of leaning toward trying to start some from seeds, if it isn’t too late. Is it?
I’m not a horticulturist but I don’t see why not. You’re a few months from frost that might kill the seedlings. It’ll be an extra year before you can cut.
Maybe plant part of the bed with seeds and another part with crowns?
ETA: We planted our bed late in the season, but with crowns. Frost caught the plants when they were poking just a few inches out of the ground, but they were fine the next year.
I planted crowns two years ago. We got nothing this spring or last except for some stringy leafy shoots. Then I just read somewhere that it takes four years before they mature and you get anything edible. Sigh, two more years before we can eat it…
We harvested a few in the third year, but yeah, the fourth year is when it really took off. Thank heaven for the wild stuff, and the neighbors. 
Home grown sweet corn and asparagus seem to be two veggies that are always better than what you get at the grocery store. I haven’t noticed much difference with cabbage, cauliflower, cucumbers, broccoli, carrots, potatoes, onions, etc., between home grown and grocery. Maybe those veggies store and travel better than corn and asparagus, so the difference isn’t so noticeable. ??
ETA: You do know that you’re supposed to let it keep growing until fall? Don’t cut those spindly stalks. We don’t cut ours back until March.
I can’t find any crowns anywhere right now, and the seeds say to start them indoors 12 weeks before the last frost. I’m thinking this might not happen this year. 
We’ve got a big potato bed, with 5 varieties of potatoes not-available in the supermarkets, so I’m really excited about those. Also, raspberry bushes are in the ground, and we’ve got basil, tomatoes, carrots, greenbeans, peppers, sweet peas, lettuce and squash going.
So I think I’ll put something else in the asparagus bed for this year, and start them next year, early spring. Any suggestions?
Cucumbers? Too late to start seeds, but you might be able to find some sets. We use cages for ours.
I’d plant crowns now, then if you still want to grow from seed, do it early next spring.
Mine are in their 4th season now (grown from crowns), and for some reason I have half a many as last year. But I have a bumper crop of weeds.