Pour some peroxide on the soil, take them out of the shed on north side of your house or not sunny area and turn on their sides. Too much moisture and lack of air is no good.

I have been overwintering some hostas in pots with success by simply putting on their side and under my lilac trees. I have never had the nerve to try the inside thing only because of the sudden change of temperatures we are getting. Just on the weekend we got + 5 and today it's -14. I am in zone 4 and have had snow now for a month. Hopefully you will be able to save your babies.

PS-The peroxide will kill the bacteria and the javex will do the trick on the mold.

in other words.. im not sure there is an emergency here.. that requires being fixed in the next few minutes ....

i have had much luck with benign neglect.. lol ... but i have killed a lot of things with too much love ...

ken

I think removing the lids for some air sounds like a good plan..there does seem to be more mildew/mold on your plants than on mine..my soil has more bark than peat but you're careful with planting mix so it doesn't seem as if that would be the problem..I bet they'll be fine..

lindalana, I haven't heard about the use of peroxide on plants before. Is that something you yourself out yourself or something you read about? Our weather has been around the freezing mark during the day. I feel like the top of the pots is not totally frozen. Putting the pots on their side would mean some media would fall out. I wouldn't want to lost any media and expose the crown any more than it needs to be.

Shadow, your temperatures are quite variable, but you say you have had success overwintering your pots outside. I have found that keeping pots in our attached garage is a great place. The temperature swings are not a worry. It is, in fact, my number one choice for overwintering. I just don't have access to a lot of space in the garage. That's why I'm always "on the hunt" for new overwintering locations.

Ken, the idea of using insulated containers is a new one for me. Last year I overwintered in an uninsulated large container with some success. I figured an insulated one would be even better. This year the fall temperatures were up and down and many of the leaves did not turn to mush or dry out. The hosta were in the container for no more than two weeks before I had a peek.

Nicholsworth, my pots have more bark than peat in them too---well, at least most of them. I think your pots, being uncovered outside, would have a limited amount of mold. I think it is a good idea to remove the leaves if possible. Most of the leaves that remained on the pots in the boxes were easily removed now.

I removed the lid from the hosta in the small shed. There were two hosta in that box that had mold. I kept them outside for several hours and then put them back in the shed for the night. I plan to do the same tomorrow.

Here is a picture of the small shed packed for the winter---with the insulated box.

Pictures of the two hosta with mold from shed.

The other box is on my porch and I removed the lid for several hours today. I will do the same tomorrow. Unfortunately after that temperatures will dip and be very cold. Not sure about what I will do then. Maybe like Ken says, I don't need the top at all?

newhostalady..my pots were out until late Oct/early Nov..don't know the exact date..then I put them in my unheated shed..I put them in a black garbage bag to keep the shed neater..the top of the bag's open..I didn't pull the drawstring..the hostas had leaves and the soil was damp when they went in..have no idea how they look now..I haven't seen them in weeks..I can see that your mix has a lot of bark..wondering - wouldn't freezing temperatures kill the mold?..but if you didn't clean up the pots do the spores grow again when the temps go up?..wanted to say that I've heard of people using coolers to overwinter plants..the same idea as your box..

You raise some good questions nicholsworth. I'm afraid I don't have any answers.

I have to say that not all the pots in the containers had mold on them---at least I couldn't see it with the naked eye. I can also say that not all my pots are planted in a bark mix. In one of the containers there were two pots that had mold. One was planted in 511 and the other was in a more peat based media. The peat based one was purchased this year and not repotted. So why then were the other pots OK? I am thinking it has a lot to do with the amount of moisture in the media and what kind of media it is. In the other container, there were two that were badly moldy. I will have to take a look tomorrow to see which hosta there are and what the media is.

Actually, now that I look at the last two pictures, the last one is in a peat based mix. The second last one does have bark on it, but sometimes I put bark on the top to protect the crown during winter. I am wondering whether under the bark is a peat based mix also. I can see that each of those pots still have a store tag attached to it (meaning I didn't repot them). Well, I will investigate tomorrow and see whether the peat based mixes are the ones that have mold on them.

You wrote: " I haven't heard about the use of peroxide on plants before. Is that something you yourself out yourself or something you read about?"

I don't know if you remember Moccasin, but she used it regularly. She had problems with southern blight and used it for that. Her husband was an engineer, and he figured it out from some solution that she had purchased.

I'm a long way from your zone, so have no personal experience there, but I'll voice my opinion anyway.

The reason for protecting potted hosta is so that they do not thaw halfway and leave the crown setting in water, which would cause crown rot. If you (anyone where it's really cold) leave them setting out in the weather, they will get rained on and then freeze. Given the length of your really cold temperatures, the pots are unlikely to thaw completely so they can dry out. They probably thaw a little toward the top, but not all the way through, so that water just sits there instead of draining. That is the problem. The water has no place to go if the bottom is still frozen, as the only drainage in a pot is at the bottom.

The whole point is to keep the hosta in the pots dry (or just barely damp) through the winter. They don't need protection from the fluctuations in temperature.

If fluctuations in temperature hurt them, mine would die every winter. As an example, it was about 25 F. overnight. It will be 59 F this afternoon. The weekend afternoon temperature is supposed to be in the mid 60s.

bkay

let us know what happens..in the last few years when I plant new plants (whether in the ground or a pot) I find myself removing a lot of the original soil..I have a pot that was never drilled that I use as a work pot..I hold the new plant over my pot..loosen the roots..and the peat and perlite drop off..then I give it to my best neighbor buddy that grows lots of annuals in pots!..she knows I don't think it's a good mix but she always takes it when I offer..I think this process has been better for my plants..

bkay, always love to see your comments, even if you and I live in very different zones!

I do remember Moccasin. I have wondered whether she continued her love of hosta and what her garden looks like now. I don't recall that she used peroxide. It's a good thing to know!

Water seems to be the problem in winter---too much = rot; too little = shrivelled roots. You note that temperature extremes are not a factor. Your example ranged from 25 F to 59 F. I have to wonder if there is any difference if we are talking about 32 F to 0 F?

Nicholsworth, I have found that it is very important to remove all media when repotting or planting new hosta in the garden. (I just don't always do it the first year of purchase due to lack of time.) The media is usually peat based. I think it is a good media for adding to the garden. I personally don't add it to my garden for fear of the hosta virus. Depending on the source of my hosta---if I can't be sure the hosta is not virused, I set the media aside to use in my containers that don't use hosta.

So many times I have unpotted a new hosta to find the roots entangled in the peat moss like liner that has been used to grow the hosta. The young hosta have grown in these peat pots and then dropped into larger pots to grow on and sell. That original peat pot is tough stuff. When removing it from the roots, one has to be careful not to break the roots.

I haven't checked on the pots that had mold on it because we got snow and it's gotten very cold. But I know which hostas had the worst mold and will definitely check what media is in the pot and if and when it was repotted. I will also check how wet the media seems to be.

My plants were in pots outside last year and we went down to minus 26 F. Nothing happened. Cold is not a reason why you loose hosta.

Peroxide use is very common. Mostly indoor because lack of airflow causes damping off and that is what you have with moisture and no air in your box.

Outside I have used peracetic acid but fir growing plants. I think it is less important than giving air to your pots,and I mean moving air not just keeping top open. My 2 cents of course, I have seen so many people with different set ups...

newhostalady..I forgot to mention it but I've cut fabric sleeves/liners away from roots too..aggravating isn't it?

i am in the cold side of z5 MI ...

when i moved from suburbia to the prairie ... i had 1675 pots ... frozen

about half were stored outside the pole barn.. stacked on their sides.. piled on top of each other ... media facing out ... why stain the barn.. eh ...

and rest were inside the polebarn .. piled one on top of another to about 6 feet ...

i lost none do to any of that ...

the biggest problem.. come early march.. with a late may last frost date.. is the ones INSIDE THE BARN .... started coming out of dormancy early due to accumulated heat ... and then i had actively growing potted hosta... that needed to be unstacked.. and moved outside the barn .. and with repeated thaws and freezes .. and spring rain on frozen pots.. i ended up losing a lot of hosta ... i must have blocked that memory.. but it was around 500 or so ....

i see no reason.. why in your zone 6... you need insulation .... i think you made it a lot harder than need be ...

i see no reason this needs to be fixed now ... come spring.. you can remove the gelatinous goo of rotted leaves ... and then.. AND ONLY THEN ... might i consider treating the media ...

you have taken a plant.. hosta.. that are able to live down to z3 i believe... and in z6 are babying the heck out of them.. perhaps creating more trouble than it was worth ...

i would leave the top off.. and simply forget about them.. until the spring rains start.. and then perhaps... cover them.. IF THE POTS are frozen ...

and in the spring.. whatever ones are having a hard time... well ... wait for it.. throw them on the driveway .. and run them over a few times ... it will either cure them.. of put them out of your misery ...

ken

ps: are mold and mildew even really a soil issue in the frozen north???.. who cares whats on dead leaves ... it a whole other world.. for these warm zone peeps in CA and TX ....

Well, I am glad we are having this discussion. It really helps to clarify some issues in regards to overwintering.

As for keeping the hosta in a box with the top open and air flow---I have overwintered in a window well which is covered by a wooden walkway. The wooden walkway has small gaps between the boards, but I don't think there is that much air flow. I've never been aware of hostas in there becoming moldy. But, then again, I don't see them after they are put in until early spring!

The insulated boxes seemed like a good idea to keep the hosta from extreme temperature changes more than anything. I agree that airflow is important---the mold has certainly taught me that! No more tops on insulated boxes! It seems that the more peat in the media, the more chance of getting this mold if the pot is not exposed to some air.

Ken, the loss of about 500 pots---after all the work to change locations---must have stung deeply. Your loss, it seems, is our gain. For experience makes for a very good teacher! Your lessons have been noted!

The weather continues to be unsteady here. For the next few days (at least) we will have temperatures in the daytime above freezing. The nights will be around the freezing mark. I would think this would lead to the top of the pots becoming unfrozen. And if the pot was on its side, some of the media would fall out. That can't be a good thing. In addition there are those pesky squirrels looking for trouble!

Next year I could try an experiment and put a few pots against our unheated garage which faces north. But if we go through these temperature swings, would I have to place the pot right side up when mild so the media doesn't fall out---and then lay them sideways when freezing?

As you can see, I have time in the winter to ponder all my thoughts!