I work in a micropropagation lab just sub-cultured our hosta yesterday. This is almost exactly the process we use. I have a hard enough time getting tiny plants apart with a scalpel, I can't imagine trying to divide one this big.
Gosh, mine has been overgrown for years. They are now coming over into the walkway. I've been so scared to uproot them. They are in a great shade spot. Now I feel a bit more confident. Once they start to go back into the ground in the fall, I'll separate them. There is no telling how many plants are in there 🤦🏾♀️. At least I can put some under another tree and fill out some bare spots in my yard.
I had some overgrown hostas in my front beds; couldn’t even get a clump up with a shovel. Ended up having to cut some of them so I could get to the roots and cut the clumps *before* I could shovel them up.
It does well in full sun until it gets really hot. Mine thrive from Spring until like mid July and then the sun absolutely fries them. (In North Carolina)