Sprinkle the damaged crown with root hormone, plant it, and move on. It should be fine. It will wilt some, then recover fine.

I received this advice from a moderator on the AHS Facebook group page:

First wash them off preferably with hydrogen peroxide, then let the cuts dry in the sun until the surface is completely dry and hardened (1/2 hour or so). Dust with a fungicide if you have one and replant out of any direct sunlight. They should grow fine. All the above is to prevent infection that would cause it to rot off.

who is the facebook moderator ... seriously?????

crikey.. its a hosta... throw it on the driveway for an hour.. then replant it ...

whats to lose.. ??? ... why even consider throwing it away ...

imo.. kind of a waste of rooting compound and fungicide.. its a hosta ... crikey ...

in my MI ... dividing into small pieces this late in the year.. MIGHT lead to heave ... so any small parts i would mulch deeply late in fall ... big chinks.. who cares.. its a hosta ... if you dont know what heave is.. forget about it.. [btw.. never hurts to mention where you are in every post... big city name.. alone alone means nothing. though i z7 you dont know what ground freeze or heave is..]

hosta grow roots starting in july ... to store energy for next spring.. that would have been the best time to divide.. if not in spring ... this time of year.. there wont be a lot of root growth as the soil starts cooling ... so its basically going to sit there until spring .. at which time it will come up on stored energy ... and how big it is next year.. depends on how much root is attached to it .... regardless.. with a giant hosta.. division can cause 3 to 5 years.. before it grows enough root mass to get back to giant size ...

ken

ps: and odds are.. if you just throw it under a shrub for the whole winter.. it will live thru such.. if no varmint come along

More on my day:

I had planted a trio of Sum & Substance on the west side of our house, centered on a window. One of the three hostas was not doing well, so I dug it up and potted it in the spring (its rehab is going well, but it's still quite small).

Today's goal was to divide the larger hosta on the right into two pieces to replace the puny one that was removed.

I tied up both hostas and removed the impatiens.

It took some time and effort to get the hosta out of the ground, but it was not an ordeal. Today has been our first comfortable not-too-hot Saturday of the incoming fall.

I wanted to divide this into two equal pieces, but I couldn't see a good division down the middle. I ended up cutting towards the center from two sides with about a 130-degree angle between the cuts.

Even with the cuts it took some force to separate them. One crown split as I shared in the original post. I followed the advice to clean and rinse with hydrogen peroxide and let them dry before planting. I don't have any anti-fungal powder on hand, but I did apply some rooting hormone.

There's a foxglove close behind the hosta on the left. I think I'll leave it there until it blooms next year, then remove it.

Ken, ha, yes, being a Facebook group moderator is not much of a gardening qualification, is it? But I'm familiar with the guy's posts and I respect his opinion.

Clearing out that one split crown would have still left me with sizable divisions -- but it may have been troublesome to get it out without further damage.

Anyone want to hazard a guess as to what might cause a finger-size tunnel under an impatiens?

Voles

Actually, the advice to wash and dry isn't that different from just throwing it on the driveway for an hour ... and it keeps the dirt off the driveway ...

Looks like you did just fine! Anything with part of crown and roots will grow. Plant any of the smaller divisions, in any blank space you have, and if they come back next Spring, goodie, goodie. You can dig them up and plant them else where or pot them up.

S&S is not a froo-froo hosta, and if the voles don't get it you will be fine. Bruce Banyai used to use 10%f bleach for up to overnight (!) to kill anything unpleasant.

I've been lopping apart liriopes here with a shovel. Sometimes with a serated knife. Same thing. Right thru the crown material, and hope for the best. The bigger the division the better the likelihood of it coming back in Spring. Hostas are tough, unless you just paid $150 for that plant.

-Babka

like Ken I haven't used rooting compound, fungicide, hydrogen peroxide, bleach etc..

I grab a garden fork..tie up the hosta (if necessary)..dig it up..replant..I usually don't split them..I like big plants..when I move small ones they seem to split naturally..that annoys me sometimes..it's more work to replant Lol..

plant whatever you end up with..small..medium..large..

just let nature take it's course..

Actually, the advice to wash and dry isn't that different from just throwing it on the driveway for an hour ... and it keeps the dirt off the driveway ...

==>> correct blueberry... and its FREE ... money for more hosta ...

im not a tree hugger.. so i dont mind using products WHEN NECESSARY ... but hosta is the driveway plant .. along with daylily ... so why waste the money ... if you have it laying around.. whatever ...

since they arent growing roots now.. what is the point of rooting compound ... EXCEPT.. many of they include a fungicide.. so they do have some use on cuttings ...

im pretty sure that is a vole hole.. and they eat hosta roots in winter ... ive never fought them.. so i will defer on that....

and my only beef on FB mod.. is making the simply harder than it need be ... its a hosta...

ken

Bungee cords work great too.

Garden fork is great for dividing plants ... two is even better ... put them back to back and pry apart. For small plants, just use those little three-fingered hand tools. Last time we divided a chunk off a hosta (different color chunk on an undulata) we just stuck a shovel into the plant and popped out the group of eyes, plunked it in the ground elsewhere.

Daylilies ... yeah yeah, they move well, too ... when we took out a section of one of the gardens (it was an overgrown mess that was half volunteer blackberries), we just scooped out the daylilies and bearded iris, threw them in a heap in the yard, hacked the thorny mess, and then sorted the daylily clumps for weeds, basically removing most of the dirt in the process, before replanting (didn't want to transfer creeping bellflower accidentally) ... oh, and did I mention it was mid-summer? They all did fine.