Width is the span that the leaves reach out to.

Agreed. It's the drip line of the leaves.

It's where the leaves span out, but it will take some time to get to that size. Those width statistics are estimates. My guess is that they are using a 10 year growth number, like many other plants. Theoretically, Hostas can get wider than that. It's good to know this number if you are using a hosta as a specimen (like Don-r's Sum and Substance). But many gardeners don't mind hosta leaves touching each other and will plant closer than those width estimates. Hosta sizes, Mini, Small, Medium, Large and Very Large, are determined by height and not width.

Steve

This is my very old Samual Blue. It is 84" x 36". The plant itself is 16" wide where it emerges from the ground.
{{gwi:983049}}

LOL Steve, I yelled for my DH the other day and he thought something was wrong, nope, I was very excited that my Earth Angel leaf was touching a Komodo Dragon leaf. I am so envious of everyone's pictures where their hostas touch each other. We have over 250 hostas and not very many of them are touching each other yet.

Regarding the Samual Blue, you indicated that it was 16" wide where it emerged from the ground. So, if I had a hosta that was going to be large like Samual Blue, it would be OK if I built a 24" x24" raised bed to put it in?

I think a 24" x 24" would work for a giant. The roots on mine come out an additional 10 to 12 inches all around. I took four starts off of it last year. I have had my giant for over 20 years at three different houses and it has sat where it is now for 11 years.

Depends on how high you raised the bed...Hostas of great size need a place for those roots to grow....also hostas like water...LOTS of water and a raised bed drains fast.
I wouldn't plant anything larger than perhaps a medium large plant in a 24 by 24 inch bed.
Linda C

You'll find out,also that hostas will grow greater than their estimated size,if they like where they are sited! I have found that to be true in my gardens. Phil