Can one just amend a small area to plant asparagus? Or does a large area of the ground need to done if it spreads?
The only way gus spreads is by germinated seeds. The crown certainly does not migrate nor does it send out runners--nor can you divide that crown. Even the supposedly all-male varieties are only 75% male, so a few will still bear seeds. You can contain any spreading plant by weeding, mulching, mowing, or creating barriers.
I like single clumps to spread.
keepitlow - it will gradually increase in spread but not agressively like raspberries or other running plants. But you also need to remember an asparagus bed can be in place for years so thorough preparation is important. Get rid of all perennial weeds and make sure the soil is in good condition, deep and fertile. Your asparagus will be in it a long time.
Well I guess I've done it wrong. I have devided spred clumps of asparagus and had it grow out in the new location. So if the crown doesn't spred and you only get new growth from seed I guess I did it wrong. For now Ill vote for it spreds.
Expanding our view a bit, I've never had a client who didn't want to expand their asparagus bed. One or two crowns will only whet your appetite and be at best a couple meals after many years. Homegrown asparagus is sooooooooooooooo much better than those green things from the store. You'll see. And want more.