I have no idea what temps pom roots can take but roots are always more sensitive to cold than parts above ground. How much the shed moderates temps is also impossible to say.

Trees that survive winters in the ground can often be killed when left in pots that aren't adequately insulated. That's all I can tell you. I'd protect the roots and tops.

I keep my pots in an attached garage. Haven't had any issues and that garage is not very well insulated (the 16x7 garage door has no insulation on it/something I need to address soon). I had strawberries die when I left the pot on a deck all winter. My winter temps vary between -20F and -25F every winter with lots of nights below 0F.

U won't know until you try.

Hey harvestman,
How would you protect pots in an non-attached garage/shed? wrap a piece of carpet around the pot area as well?

franktank, don't have space in the attached garage.

Guess this is some good info:
www.hgtv.com/landscaping/the-cold-hard-facts/index.html
http://www.gardensalive.com/article.asp?ai=642

You usually insulate pots with something that won't get wet- like styrafoam.

I leave mine outside all winter - covered in hay or straw. Works great and spring removal is pretty easy. We do several hundred to several thousand potted trees like this every year - haven't lost very many (if any) to cold. - We're in Eastern Kansas on the border of zone 5/6.

Hay or straw would work fine- I was thinking in terms of keeping everything neat as I've only observed insulated pots on estates as permanent landscape features.

I have hundreds of potted trees also and used to mound up arborist chips to protect them- now I set them in the ground year round and let roots grow out of them into surrounding soil. I sell them as half bare roots and they establish exceptionally well.

the base problem with pots.... IMHO ... is that the media temp has the potential to fluctuate wildly due to air temps ... one winter day being 60 .. and then that night being zero ...

if the pots get that warm.. for too long [say three or 4 day heat wave in Feb.] ... then the roots have the potential to come out of dormancy ... while the rest of the plant does not ...

i used to say in general .. they can deal with it once.. the second time they are damaged.. and the third time.. the heck with you.. the plant dies ... [active roots in cold media leads to root rots]

so ... on an otherwise zone appropriate plant.. its not that you are protecting the roots/pots from the air temp .. as much as protecting them from wild fluctuations in media temp ...

the key is always.. GET THEM DORMANT .. KEEP THEM DORMANT .... for all of winter/storage .... and that is what kansas is doing above .. with straw ...

the blanket of mulch.. does not protect as much from the air temp.. as retain the ground temp.. to temper the air temp fluctuation ... by covering otherwise dark soil.. from winter sun.. the soil stays cold ...

so though i have no direct experience with pom's .. i see no reason why the logic would be any different .... the pots must be protected ..

good luck.. i have lost most battles with extreme zone pushing.. but that never stopped me from trying ....

ken

Ken, that is interesting but I wonder where you got that info. I'd really like to see it from the source as I've never heard of roots coming out of dormancy- I've always understood it as the roots never go into dormancy. I love learning something new but when I go into the woods in winter and reach into the loam under the rotted leaves there's always plenty of fresh white feeder roots only days old.

Hey Harvestman, Doesn't something happen with the roots though going somewhat dormant?
As energy is being transferred and stored there in autumn for breaking dormancy next spring? Like I thought the plant doesn't feed during the winter, just needs enough water to keep roots moist right?
People say minimally water the roots with snow on top of the pots (if moving figs into an indoor garage for example), so i assume the roots themselves don't 'do' much during dormancy.

hey harvestman ....

that is personal experience in my z5 ....

i will submit.. that i spoke authoritatively ... as if it is backed by science ...

but once i comprehended that if you GET THEM DORMANT ... AND KEPT THEM DORMANT .... my success rate went from 50/50 to 95% ....

the early experience was hybrid T roses ... where unprotected canes.. will thaw on the sun side.. and not on the dark side... and that happening repeatedly ... will kill the cane.. and if that goes all the way to the graft.. it is dead ... and why here.. in the great white north.. we bury the plant to about 6 inches in loose mulch.. and then put a styrophome cone over them ... no sun.. no wind.. and a thermal breaker for ambient air temp changes ....

and the theory was reinforced when i moved 1700 potted plants of all kinds in january 2000 ... and put some in the pole barn ... which came out of dormancy early.. because the barn ended up a z7 .. and i had plants coming out of dormancy 2 to 3 months prior to last hard frost ...

versus those allowed to freeze solid.. and stacked on their sides on the north side .. outside of the barn .. where they stayed frozen/dormant.. until near last frost ...

as i said.. IMHOpinion .... its all about stressing the plant.. by going in and out of dormancy.. whether it is the roots.. the plants.. the bark.. the liquids inside.. i do not know ...

and i doubt it is much of an issue ... south of z6 ... its just that zones 5 and 6 .. are so flexible ...

anyway.. good luck

ken

I'm no botanist and am too busy to research this, but when I was in hort-school (went there after 20 years in the soil) the word was that roots never sleep- however that was more than 20 years ago and there are many possible stages of winter hardening as far as the top of plants are concerned so maybe there's also a physiological change that occurs in the roots during winter that is akin to a partial hardening off.

i dont know if roots actually sleep..

but in ground freeze.. i usually say they are in suspended animation ... i just cant comprehend that they are growing/pumping .. or elongating in frozen soil ... again .. up here in z5 and colder ...

sounds like a good thesis for some aspiring student ....

who knows

ken

I'm sure frozen roots don't grow but the roots are going to have activity in parts of the soil not frozen. If snow comes early the soil may not freeze at all- even in Z5. I believe trees need to have some part of their roots working at all times if only to avoid dessication.

In the forest, leaves generally insulate the soil so well that even without snow the freeze can't penetrate deeply at all.

Turf does a pretty good job of insulating as well.