I'm in zone 6 where temps get below 0 in the winter for periods of time. I've never lost a hosta by overwintering it in a pot. I just leave it out in the yard. I've overwintered in pots of all sizes. Several winters ago, I divided some of my August Moon hosta and left a few pieces, bare root, sitting in a container and totally forgot about them. After an extremely cold winter, I found them leafing out in the spring.

I have had success overwintering them in pots. The key is making sure that no moisture gets into the pots over the winter. I wait until after a hard frost, then move the pots to the northern side of my house, tip the pots on their side, and cover them with leaves.

I have also sunk pots in the ground and covered them with leaves, and have never lost a hosta that way.

I have only lost two hostas in pots. One because I didn't tip it on it's side and left it out in the open (forgot about that one), and the other because I had it tipped on it's side and unbeknownst to me my husband kept blowing snow into the pot all winter (not on purpose).
Jen

That is a goood strategedy for any zone. I'm in zone 9 (or 8b depending on whose whose maps you choose), and even though my pots never freeze, hostas do not like to get cold and wet in pots when they are dormant. Once they go dormant and the leaves die back, they really don't need any more water until noses poke up in Spring.

-Babka

I have one very big pot under my front porch, had 3 hostas in there last year under mulch, left it standing up, piled snow in it over winter for good measure, all 3 hostas died probably from crown rot.

first issue.. is the pots themselves ....

fired or ceramic pots should be ok .... but water expands as it freezes ... and when the ice forms.. it can break them ... so perhaps the easiest thing.. would be to heel them into the garden .. and repot in spring ... as the buds start extending ...

compare to the plain old terra cotta clay pots.. they themselves suck in water.. and they will surely crack when freeze hits ..

so first.. if you have the wrong pot ... you have to remove the hosta.. and figure out how to store the pot ... DRY!!!

now.. move to the hosta ... the roots can NOT survive.. if they freeze into an ice cube ... so as per above ... margo.. they need to dry a bit.. and if a plastic pot.. its as simple as placing them out of ALL WINTER SUN.. so the pot itself does not heat in the sun.. and laying them on their sides ... in late november ... i even had about 500 of them stacked on top of each other against the wall of the polebarn .. once frozen ... on their sides ...

out exposed to nature.. in the shade they should be near bullet proof ...

next.. they do NOT come in the house for 'storage' NO MATTER WHAT ....

finally ... [probably not.. lol] ... any structure is easily.. 2 or 3 zones warmer ... since it traps day heat.. and doesnt get as cold at night ... which means your hosta will start coming out of dormancy a month or 3 early .. which will excite you early on.. until you realize you are not frost free until nearly june .... you have 2 options ...

you could bring them in the house at that time for an early 'forced' display .. but the furnace will make the house very dry for them.. and they might be spent by late july [ugly] ... their season will be early.. and over fast ...

or when the snow melts.. and they are still in full dormancy.. you could just line them up on the north side of the house.. so at night they stay cold.. and stay in full dormancy.. until the more proper time. ... but if rain is possible.. you would lay them on their sides.. again.. because a pot with frozen media might trap the water.. and a frozen hosta will not like trying to breath with its roots in an ice cube ...

there was something else.. but the caffiene rush is addling my brain.. will report back when it comes to me ....

this topic has been covered many time.. and by using the search function within GW.. you may find many more posts .... if you care for more ideas .... wintering over pots is not specific to hosta.. so the type of plant discussed does not matter ...

oh ... i recall ... if you have just a few.. and you line them up in a structure... come about xmas or so ... put a couple ice cubes.. or a snowball on each ... such will melt when the temps warm.. offering a LITTLE moisture as necessary ... w/o drowning them .... do this once a month or so .. NEVER FORGET.. in the cold white north.. winter is the driest season of the year.. near desert ... in that almost all water is tied up in frozen form.. so though we do not want to 'water' them.. we dont want them getting so dry.. they root rot and die ... think a piece of chicken poorly wrapped in the freezer .. and extend such logic to the roots ...

good luck .. believe it or not.. its not that hard ...

ken

Sooo many variables! I have overwintered hundreds of Hosta in pots and never tipped them on their side. These were in Z5 and Z6. My plant losses have been less than 2%, which I don't consider bad since many were fresh divisions of immature plants. (I have made a secondary hobby of the various form of propogation of all kinds of plants. I don't sell plants, I give them away.) Don't misinterpret what I am saying. If I could not lose a single one I would be happier and if tipping the pots will accomplish this I am all for it. I may try dividing a couple of lancifolia just to try it and see what results I get. But then I have not found yet how to kill a lancifolia.

At one time I did an experiment for a two year seanonal period. All the Hosta I purchased were repotted and overwintered the first winter. Then they were planted in the ground the next spring. I did plant a few in the ground the first year as a "control" reference to supplement my experience. All of the potted plants matured more quickly, grew larger and seemed healthier, than the control plants. The success was so impressive I decided that I would use this approach whenever I could. This fits into the scope of the original question. I never tipped a pot, yet I was so confident in the results I was getting I never even considered a bit of snow on a dormant potted hosta a threat.
Les

How does a hosta survive a freezing zone 5 or 6 winter in a 4" pot and a small root system? Can it be just left in an unheated garage ( drafty ol' one) out of the severe elements. I have a few young ones that I would rather not plant this fall.

I also overwintered about 18 mature hostas in a detached garage from November as I was moving house . I did not water and they were only lightly damp but in about Feb the soil felt dry so I put a shovel of snow on them. The eyes appeared a little early and I replanted them in April/May. I did not lose a single one.
Good luck.

For young ones in 4" pots, would it be more feasible to just plant them in an unused (IS there such a thing? ) spot?