This time of year is IMHO the best time to take divisions, as this is when root growth is abundant. Just make sure you keep them well watered. Do NOT bother with bonemeal in the planting holes.

Pieter

Do not divide in high heat of summer. They will look terrible for the rest of the year.

IMO, I think spring is best. Once the noses are up, but before they unfurl.

But personally, I would rather NOT divide. Unless they're dying out, or outgrowing their space, there's no reason to divide hostas.

Wait for the heat wave to be over with. It's not even a good idea to be outside right now.

I need to move/divide some hostas as well, but it's been so hot I wouldn't risk it until things cool down a bit. I'm planning on doing the moving/dividing at the end of August, where we still have warm days left and by then the hostas leaves are already going downhill so if they look a mess after moving/dividing, it won't be so bad. And though spring would be more ideal, I have some hostas that A) need to be moved this year and B) have sported all green or other unusual parts that aren't obvious as pips, so need to be taken out when in full leaf. And of course, give them plenty of water.

Karen

I was told years ago it takes about six weeks for a plant to settle in before frost...so I believe six weeks out from our first frost date is the optimum time. Hosta's will survive about anytime you divide them. I am not one who worries about what they look like "the rest of the season". If I have the time and the weather is great I do it. Next year they will look fine. I have people gushing all the time over the fullness of my gardens. When I offer to pass a few along and they hem and haw about "the rest of the season" I figure they don't want them bad enough and find someone who does.

You can move/divide a hosta at any time of the year,I would not, however, do any thing til this heat wave is over.I prefer to move them in the early spring,like mellisa suggested,it is so much easier,and they never lose a beat.So I guess it is really up to you,:0),when ever you do it, like Karen said, give them plenty of water.It's that simple.Good luck, and have fun.
cAROL

I always like the answer someone gave about when to prune trees and bushes : "whenever I have time and think about it", or similar. I feel the same about moving hostas, that is as long it is not moved into the sun. I just potted up hostas for a society sale in 4 weeks. They got a lot of compost and water and were placed into shade, should be fine there, are actually straightening out already.
There is always so much to do in spring, and spring is short in my area, so I do things when I have time.
Bernd

thanks for all your advice. I have always divided in spring also, although I too do not like to divide. These are very overgrown and all mashed together. You cannot even see some of the small ones. I am going to wait until the end of August so the leaves are still there and I can tell where they all are. And like you say if they don't look too good, it is the end of the season by then and they will be alright!! And water, water , water!!!

the link is one the front page of the library ....

check it out ...

ken

Here is a link that might be useful: link