Sounds like you need to make sure when you break up these clumps to take out dead roots and dry roots, using a bleach solution on the sharp knife to cut away dead plant tissue.

Tip them over upside down, shake out of the pot and start carving your pumpkin/oops, hosta clump up.

I would soak the cleaned clump divisions in 5-10 % bleach solution (cold water only) for 2-3 hours , then replant.

The soil mix you use to replant needs to be kept moist and cool while they re-adjust to the root pruning and dividing - have fun but be patient!

Bruce

I'm in zone 9 and grow all mine in pots. You only need to repot them if you can't keep them watered well enough to keep the leaves from getting dry edges/ or if the center of the pot dies, like my Guacamole did. You can move them to bigger pots, until you reach a place where you can no longer lift the pot w/o hurting your back. I just cut in half, Pineapple Upside down cake and Invincible. They were in pots and I noted that last year their leaf edges turned crispy even though I watered them often. Their eyes were out to the edges of the pots.

I plant mine in 80% bark for drainage. Not worried about soil as I give them a light solution of fertilizer with every watering. Sorta like hydroponic gardening. Mine all sit atop a couple redwood 3/4" sticks. SLUGGO is what I put directly under each pot to keep those awful things away.

-Diana

Why the bleach? That sounds a little bit caustic for a living plant.

bkay

Bleaching newly divided plants gives them the best overall start against opportunistic soil-borne pathogenic bacteria.

Translated another way (from a chemical engineer with microbial community experience as well) you kill bad bacteria easily with 5-10% bleach and allow the beneficial ones to get situated without the compeitition.

Same as cleaning your kitchen countertops or cutting boards every now and then with bleach.

Especially important with pot-bound hosta if there is any dead or old woody tissue which harbor the fungal spores causing disease, such as root rot. You need to make sure you cut that unproductive and potentially diseased portion oout - down to clean white tissue.

Inthe nursery business bleaching or sterilization is just good management practice to prevent spread of common soil-bone diseases. Our family greenhouse/nursery businesses have used bleach for over 70 years - especially on all field-grown hosta divisions. Have not killed a hosta division with bleach yet, and surely have tried!!

Bleach, by the way is neither caustic (high pH) or acidic (low pH) in and of itself. It is more active (from an oxidizing/killing standpoint) at slightly acidic ranges.

Bruce

Welcome to the forum. Hope all goes well with your hostas. Most of my hostas are in containers going on four years now. I have significantly cut my losses using pine mulch. So far so good this spring although half or so still have not emerged.