Hi,

Generally speaking I measure from the entire clump of the plant. You don't have to be that precise for the veggies. But each small plant now will grow over time into a clump of about 8" in diameter and more as the plant ages. Asparagus is a long life perennial that can grow for 20+ years. I've planted mine a good foot apart for future years. The first summer in the middle I plant other small veggies to utilize the space and help shade the asparagus from the summer heat.

Cheers,
Peggy

Hi I look forward to my asparagus season and plant more every year. I let them develop for 3 years without picking. Each clump develops to nearly 3 feet wide and up to five feet high so plant them as far apart as you have space. I find thay are quite tough plants once they establish. Cheers Max

I thought it was suggested 18" apart. Mine are 12" and way too close.

What other care do they need? Do they like acid/alkaline? Wet/dry? There are a few 1-2 year old plants already established in our new place, lucky us.

They don't like it wet. Loose better draining soil is best.

I am growing about 20 in 12" pots. so basically they are 12" apart. They feed pretty voraciously and are doing quite well. I would suggest an 18" separation for optimal spacing between ferns, mine seems to be a little crowded, but not complaining. The greating the spacing the greater the yield per plant but the lower the yield per square foot. So it is a trade off. I'm still first year and itching to try some. The new spears are thumb size in diameter and begging to get snapped, but I have resisted so far.
I have pests galore! The battle is non-stop with every other plant I have. Aspargus, no problems at all! The only issue I have had is, racoons/opossums stealing the odd spear or two. They seem to have quit and moved on to greener pastures.

Keep them watered during the sunny hot summer weather. Mine shriveled up without enough water. We are hot and dry in summer. They like neutral to alkaline soil. A very rewarding plant.
John S
PDX OR